Influenza Virus Vaccine Inactivated (Monograph)

Brand names: Afluria, Fluad, Fluarix, Flucelvax, Flulaval, Fluzone
Drug class: Vaccines

Medically reviewed by Drugs.com on Oct 26, 2023. Written by ASHP.

Introduction

Inactivated virus vaccine. Seasonal influenza vaccine inactivated (IIV) contains noninfectious, suitably inactivated influenza virus types A and B subunits representing influenza strains likely to circulate in the US during the upcoming influenza season and is used to stimulate active immunity to influenza strains contained in the vaccine.

Uses for Influenza Virus Vaccine Inactivated

Prevention of Seasonal Influenza A and B Virus Infections

Prevention of seasonal influenza virus infection in adults, adolescents, children, and infants ≥6 months of age.

Influenza is an acute viral infection; influenza viruses spread from person to person mainly through large-particle respiratory droplet transmission. In the US, annual epidemics of seasonal influenza occur, usually during the fall or winter. Influenza viruses can cause illness in any age group; children have highest rate of infection. Influenza can exacerbate underlying medical conditions or lead to pneumonia in certain individuals. Adults ≥65 years of age, children <2 years of age, and individuals with chronic medical conditions have highest risk of influenza-related complications and death.

Annual vaccination is the primary means of preventing seasonal influenza and its complications. Annual influenza vaccination necessary since immunity declines in the year following vaccination and circulating influenza strains change from year to year.

CDC Advisory Committee on Immunization Practices (ACIP), AAP, and others recommend routine influenza vaccination for all individuals ≥6 months of age using an age-appropriate seasonal influenza vaccine, unless contraindicated. Vaccination against seasonal influenza recommended for otherwise healthy individuals as well as those who have medical conditions that put them at increased risk for influenza-related complications. Seasonal influenza vaccination is particularly important for individuals at increased risk for severe influenza or influenza-related outpatient, emergency department, or hospital visits and those who live with or care for such individuals (e.g., health-care personnel, household or other close contacts). (See Table 1.)

All influenza vaccines available in the US are quadrivalent formulations containing antigens representing 2 influenza A strains (H1N1 and H3N2) and 2 influenza B strains (B/Victoria lineage and B/Yamagata lineage).

Several different types of influenza virus vaccines are commercially available, including an inactivated virus vaccine (influenza virus vaccine inactivated [IIV]), an adjuvanted inactivated virus vaccine (influenza vaccine, adjuvanted [aIIV]), a recombinant vaccine (influenza vaccine recombinant [RIV]), and a live attenuated virus vaccine (influenza vaccine live intranasal [LAIV]). The various vaccine formulations also differ based on method of manufacturer (egg-based versus cell culture-based), dose (standard versus high-dose), and route of administration (e.g., parenteral versus intranasal),

Select specific influenza vaccine based on age and health status of the individual. For many individuals, more than one type of influenza vaccine may be appropriate.

ACIP and AAP state that there are no preferential recommendations for any specific vaccine type or trade name when more than one licensed, recommended, and age-appropriate vaccine is available, with the exception of selection of influenza vaccines for individuals ≥65 years of age. If an age-appropriate vaccine is available and there are no contraindications, do not delay influenza vaccination to obtain a specific product.

Although most inactivated influenza vaccines are egg-based, a quadrivalent cell culture-based inactivated vaccine (Flucelvax; ccIIV) also is available.

An adjuvant-containing inactivated influenza vaccine (Fluad; aIIV) is available for use only in adults ≥65 years of age. The adjuvant is MF59C.1 (MF59), a squalene-based oil-in-water emulsion included to increase antibody response.

An inactivated influenza vaccine containing a higher antigen content (Fluzone High-Dose) than that contained in standard-dose inactivated influenza vaccines is available for use only in adults ≥65 years of age.

Seasonal influenza vaccines are not effective against all strains of influenza, but may be effective against those strains (and possibly closely related strains) represented in the vaccine.

Current information regarding influenza surveillance and updated recommendations for prevention and treatment of seasonal influenza is available from CDC at [Web].

Influenza Vaccination During the Coronavirus Disease 2019 (COVID-19) Pandemic

CDC and ACIP state that efforts to ensure influenza vaccination for all individuals ≥6 months of age for the upcoming (current) influenza season are of paramount importance to reduce influenza-related morbidity and mortality and reduce the impact of respiratory illnesses in the population and the resulting burdens on the health-care system. SARS-CoV-2 (causative agent of COVID-19) is expected to circulate in the US during the influenza season; the extent of continued or recurrent SARS-CoV-2 circulation during the time influenza viruses are circulating is not known. Vaccination against influenza can reduce prevalence of influenza illness and reduce incidence of influenza symptoms that might be confused with COVID-19 symptoms (i.e., fever, cough, dyspnea). In addition, prevention of influenza and reduction in severity of influenza illness and associated outpatient visits, hospitalizations, and intensive care unit admissions could alleviate stress on the US health-care system.

ACIP recommends that influenza vaccination should be deferred in symptomatic individuals with moderate or severe COVID-19 until recovery and deferral also may be considered in persons with mild or asymptomatic COVID-19 illness.

Influenza Virus Vaccine Inactivated Dosage and Administration

General

Administer seasonal influenza vaccine every year before exposure to seasonal influenza. In the US, localized influenza outbreaks indicating start of annual influenza season can occur as early as October and peak influenza activity (which often is close to the midpoint of influenza activity for the season) usually occurs in January or February or later.

ACIP recommends offering influenza vaccination by the end of October, if possible, and continuing to offer vaccination as long as influenza viruses are circulating and unexpired vaccine is available. Although influenza vaccination by the end of October is recommended, vaccination in December or later (even if influenza activity has begun) is likely to be beneficial in the majority of influenza seasons.

When 2 doses of influenza vaccine are required in children 6 months through 8 years of age, give first dose as soon as possible after vaccine becomes available since this allows second dose to be given by the end of October. For children and adults requiring only a single dose of influenza vaccine, there is evidence that early vaccination (i.e., in July or August) is likely to be associated with suboptimal immunity (waning immunity) before end of influenza season, particularly in older adults. Community vaccination programs should balance maximizing likelihood of persistence of vaccine-induced protection through the season with avoiding missed opportunities for vaccination or vaccinating after influenza circulation has already started, especially in those ≥65 years of age.

Administration

Afluria (quadrivalent), Fluad (quadrivalent), Fluarix (quadrivalent), Flucelvax (quadrivalent), Flulaval (quadrivalent), Fluzone (quadrivalent), Fluzone High-Dose (quadrivalent): Administer only by IM injection.

Do not administer intradermally, IV, or sub-Q.

As an alternative to IM injection using a needle and syringe, Afluria (quadrivalent) may be administered IM using a PharmaJet Stratis needle-free injection system only in adults 18 through 64 years of age. Do not administer other commercially available inactivated influenza vaccines using a jet injector.

Syncope (vasovagal or vasodepressor reaction; fainting) may occur following vaccination; such reactions occur most frequently in adolescents and young adults. Take appropriate measures to decrease risk of injury if patient becomes weak or dizzy or loses consciousness (e.g., have vaccinees sit or lie down during and for 15 minutes after vaccination). If syncope occurs, observe patient until symptoms resolve.

May be given concurrently with other age-appropriate vaccines. When multiple vaccines administered during a single health-care visit, give each parenteral vaccine using separate syringes and different injection sites. Separate injection sites by ≥1 inch (if anatomically feasible) to allow appropriate attribution of any local adverse effects that may occur.

IM Administration

Depending on patient age, administer IM into deltoid muscle or anterolateral thigh.

Infants 6 through 11 months of age: Preferably give IM injection into anterolateral thigh. In certain circumstances (e.g., physical obstruction at other sites and no reasonable indication to defer the vaccine dose), may consider IM injection into gluteal muscle using care to identify anatomic landmarks prior to injection.

Infants and children 1 through 2 years of age: Preferably give IM injection into anterolateral thigh; alternatively, deltoid muscle can be used if muscle mass is adequate.

Adults, adolescents, and children ≥3 years of age: Preferably give IM injection into deltoid muscle; alternatively, anterolateral thigh can be used.

Do not administer into gluteal region or any area where there may be a major nerve trunk.

To ensure delivery into muscle, make IM injections at a 90° angle to the skin using a needle length appropriate for individual’s age and body mass, thickness of adipose tissue and muscle at injection site, and injection technique. Consider anatomic variability, especially in the deltoid; use clinical judgment to avoid inadvertent underpenetration or overpenetration of muscle.

Do not mix with any other vaccine or solution.

Shake prefilled syringe before administering a dose.

Shake vaccine vial before withdrawing a dose.

Discard vaccine if it contains particulates, appears discolored, or cannot be resuspended with thorough agitation.

Jet Injector (Afluria)

Afluria (quadrivalent) may be administered IM using a PharmaJet Stratis needle-free injection system in adults 18 through 64 years of age. Do not use jet injector to administer Afluria in children and adolescents <18 years of age or geriatric adults ≥65 years of age.

Consult manufacturer’s information for the jet injector for specific information on how to administer Afluria using the PharmaJet Stratis needle-free injection system.

Dosage

Dose and dosing schedule (i.e., number of doses) for prevention of seasonal influenza depend on individual’s age, vaccination history, and specific product administered.

Pediatric Patients

Prevention of Seasonal Influenza A and B Virus Infections

Infants and Children 6 through 35 Months of Age (Afluria)

IM

Available in 0.25-mL single-dose syringes to provide a reduced dose for use in infants and children 6 through 35 months of age.

Has not previously received any doses of any seasonal influenza vaccine or has an uncertain history regarding influenza vaccination: Two 0.25-mL doses administered at least 1 month (4 weeks) apart.

Did not receive a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend two 0.25-mL doses administered at least 4 weeks apart.

Received a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend a single 0.25-mL dose.

Infants and Children 6 through 35 Months of Age (Fluarix, Flulaval)

IM

Has not previously received any doses of any seasonal influenza vaccine or has an uncertain history regarding influenza vaccination: Two 0.5-mL doses administered at least 1 month (4 weeks) apart.

Did not receive a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend two 0.5-mL doses administered at least 4 weeks apart.

Received a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend a single 0.5-mL dose.

Infants and Children 6 through 35 Months of Age (Fluzone)

IM

For infants and children 6 through 35 months of age, 0.25 mL or standard doses (0.5 mL) may be used.

Has not previously received any doses of any seasonal influenza vaccine or has an uncertain history regarding influenza vaccination: Manufacturer recommends two 0.25-mL doses, two 0.5-mL doses, or one 0.25- and one 0.5-mL dose administered at least 1 month (4 weeks) apart.

Did not receive a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend two 0.25-mL doses or two 0.5-mL doses administered at least 4 weeks apart.

Received a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend a single 0.25- or 0.5-mL dose.

Children 6 months through 8 Years of Age (Flucelvax)

IM

Has not previously received any doses of any seasonal influenza vaccine or has an uncertain history regarding influenza vaccination: Two 0.5-mL doses administered at least 1 month (4 weeks) apart.

Did not receive a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend two 0.5-mL doses administered at least 4 weeks apart.

Received a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend a single 0.5-mL dose.

Children 3 through 8 Years of Age (Afluria, Fluarix, Flulaval, Fluzone)

IM

Has not previously received any doses of any seasonal influenza vaccine or has an uncertain history regarding influenza vaccination: Two 0.5-mL doses administered at least 1 month (4 weeks) apart.

Did not receive a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend two 0.5-mL doses administered at least 4 weeks apart.

Received a total of ≥2 doses of any seasonal influenza vaccine before July 1 of the summer prior to the upcoming (current) influenza season: ACIP and AAP recommend a single 0.5-mL dose.

Children and Adolescents 9 through 17 Years of Age (Afluria, Fluarix, Flucelvax, Flulaval, Fluzone)

IM

Single 0.5-mL dose.

Adults

Prevention of Seasonal Influenza A and B Virus Infections

Adults ≥18 Years of Age (Afluria, Fluarix, Flucelvax, Flulaval, Fluzone)

IM

Single 0.5-mL dose.

Adults ≥65 Years of Age (Fluzone High-Dose)

IM

Single 0.7-mL dose.

Special Populations

Hepatic Impairment

No specific dosage recommendations.

Renal Impairment

No specific dosage recommendations.

Geriatric Patients

ACIP states that all adults ≥65 years of age should be vaccinated against influenza using influenza virus vaccine inactivated or influenza virus vaccine recombinant. ACIP states a preference for the adjuvant-containing quadrivalent inactivated vaccine (Fluad), quadrivalent influenza virus vaccine inactivated (Fluzone High-Dose), or quadrivalent recombinant influenza vaccine (Flublok). If none of these 3 vaccines are available, then adults ≥65 years of age may receive any other age-appropriate standard-dose influenza virus vaccine.

Standard-dose Preparations (Afluria, Fluarix, Flucelvax, Flulaval, Fluzone)

Geriatric adults ≥65 years of age: Single 0.5-mL IM dose.

Standard-Dose, Adjuvant-containing Preparation (Fluad)

Geriatric adults ≥65 years of age: Single 0.5-mL IM dose.

Fluzone High-Dose

Geriatric adults ≥65 years of age: Single 0.7-mL IM dose.

Cautions for Influenza Virus Vaccine Inactivated

Contraindications

• History of severe hypersensitivity (e.g., anaphylaxis) to previous dose of any influenza vaccine.

• Egg-based influenza vaccine inactivated: History of severe hypersensitivity (e.g., anaphylaxis) to any component of the vaccine, including egg protein.

• Cell culture-based influenza vaccine inactivated: History of severe allergic reactions (e.g., anaphylaxis) to any component of the vaccine.

Warnings/Precautions

Sensitivity Reactions

Allergic or immediate hypersensitivity reactions (e.g., urticaria, angioedema, anaphylaxis, anaphylactic shock, serum sickness, allergic asthma) reported rarely.

Prior to administration, review patient’s history with respect to possible sensitivity reactions to the vaccine or vaccine components, including egg protein, and prior vaccination-related adverse effects and assess benefits versus risks.

Administer in a setting where appropriate medical treatment and supervision are available to manage possible anaphylactic reactions if they occur. Epinephrine and other appropriate agents should be readily available.

Egg-based influenza vaccine inactivated (Afluria, Fluad, Fluarix, Flulaval, Fluzone): ACIP states that all persons aged ≥6 months with egg allergy should receive influenza vaccine with any influenza vaccine (egg-based or nonegg-based) that is otherwise appropriate for the recipient’s age and health status.

Cell culture-based influenza vaccine inactivated (Flucelvax): ACIP states do not use in individuals who have had a severe allergic reaction (e.g., anaphylaxis) to any trivalent or quadrivalent cell culture-based influenza vaccine or to any component of the vaccine. However, ACIP states that a history of severe allergic reaction (e.g., anaphylaxis) to any other trivalent or quadrivalent type of influenza vaccine (egg-based inactivated vaccine, recombinant vaccine, live intranasal vaccine) is a precaution to use of the cell culture-based vaccine. If Flucelvax is used in an individual with such a history, administer the vaccine in an inpatient or outpatient medical setting supervised by a health-care provider able to recognize and manage severe allergic reactions. Consider consultation with an allergist to help identify the vaccine component responsible for the prior reaction.

Egg Allergy

Most seasonal inactivated influenza vaccines (Afluria, Fluad, Fluarix, Flulaval, Fluzone) are produced using embryonated chicken eggs; these vaccines can contain residual egg protein (ovalbumin).

Flucelvax inactivated influenza vaccine (quadrivalent) is cell culture-based and prepared using virus propagated in Madin Darby Canine Kidney (MDCK) cells (not embryonated chicken eggs).

Manufacturers of egg-based inactivated influenza vaccines state that these vaccines are contraindicated in individuals who have had a severe allergic reaction (e.g., anaphylaxis) to egg protein.

ACIP states that all individuals aged ≥6 months with egg allergy receive influenza vaccine with any influenza vaccine (egg-based or noneggibased) that is otherwise appropriate for the recipient’s age and health status. ACIP no longer recommends that persons who have had an allergic reaction to egg involving symptoms other than urticaria should be vaccinated in an inpatient or outpatient medical setting supervised by a health care provider who is able to recognize and manage severe allergic reactions if an egg-based vaccine is used. Egg allergy alone necessitates no additional safety measures for influenza vaccination beyond those recommended for any recipient of any vaccine, regardless of severity of previous reaction to egg, as all vaccines should be administered in settings in which personnel and equipment needed for rapid recognition and treatment of acute hypersensitivity reactions are available.

Neomycin and/or Polymyxin B Allergy

Afluria (quadrivalent): Each 0.5-mL dose contains neomycin sulfate (≤81.8 ng) and polymyxin B (≤14 ng).

Fluad adjuvant-containing (quadrivalent): Each 0.5-mL dose may contain trace amounts of neomycin (≤0.02 mcg by calculation) and kanamycin (≤0.03 mcg by calculation).

Neomycin hypersensitivity usually manifests as a delayed-type (cell-mediated) contact dermatitis.

ACIP states that a history of delayed-type allergic reaction to neomycin is not a contraindication to use of vaccines containing trace amounts of neomycin. However, before giving a neomycin-containing vaccine to an individual with a history of anaphylactic reaction to neomycin, have patient evaluated by an allergist.

Thimerosal Allergy

All multiple-dose vials of influenza vaccine inactivated (Afluria, Flucelvax, Fluzone) contain thimerosal as a preservative.

Hypersensitivity reactions to thimerosal contained in vaccines have been reported in some individuals. These reactions usually manifest as local, delayed-type hypersensitivity reactions (e.g., erythema, swelling), but a generalized reaction manifested as pruritus and an erythematous, maculopapular rash on all 4 extremities has been reported rarely.

Even when patch or intradermal tests for thimerosal sensitivity are positive, most individuals do not develop hypersensitivity reactions to thimerosal administered as a component of vaccines.

ACIP states that a history of delayed-type hypersensitivity to thimerosal is not a contraindication to use of vaccines that contain thimerosal.

Guillain-Barré Syndrome (GBS)

If GBS occurred within 6 weeks after previous influenza vaccination, manufacturers state base decision to administer influenza vaccine on careful consideration of potential benefits and risks.

The 1976 swine influenza vaccine was associated with increased frequency of GBS. Evidence for causal relationship between other influenza vaccines and GBS inconclusive; if an excess risk exists, it probably is slightly more than 1 additional case of GBS per 1 million vaccinees).

ACIP states that, as a precaution, individuals who are not at high risk for severe influenza complications and who developed GBS within 6 weeks of a previous dose of influenza vaccine generally should not receive influenza vaccination; clinicians might consider use of antiviral prophylaxis for such individuals. However, ACIP states that the benefits of influenza vaccine may outweigh the risks for certain individuals with a history of GBS within 6 weeks after a previous dose of influenza vaccine who are at high risk for severe complications from influenza.

Individuals with Altered Immunocompetence

May be administered to individuals immunosuppressed as the result of disease or immunosuppressive therapy. Consider possibility that immune response to the vaccine and efficacy may be reduced in these individuals.

ACIP, AAP, CDC, NIH, IDSA, and others state that HIV-infected adults, adolescents, children, and infants ≥6 months of age should receive annual vaccination against seasonal influenza; use age-appropriate parenteral inactivated influenza vaccine (not intranasal live vaccine) for prevention of seasonal influenza in HIV-infected individuals. Antibody response may be inversely correlated with severity of the disease. Use of an additional (i.e., booster) dose of influenza vaccine does not appear to improve immune response in HIV-infected individuals.

Generally, administer prior to initiation of immunosuppressive therapy or defer until immunosuppressive therapy discontinued.

Even if previously vaccinated against influenza, ACIP recommends that hematopoietic stem cell transplant (HSCT) recipients should receive age-appropriate influenza vaccine inactivated ≥6 months after HSCT and then annually thereafter. Although influenza vaccine inactivated can be given as early as 4 months after HSCT, some experts state consider a second dose in this situation.

Fever and Febrile Seizures

Febrile seizures reported rarely following administration of influenza vaccine inactivated.

Postmarketing reports of increased rates of fever and febrile seizures in infants and children 6 months through 4 years of age and increased incidence of fever in children 5–8 years of age who received a 2010 Southern Hemisphere parenteral inactivated influenza vaccine that was antigenically equivalent to and produced by the same manufacturer as one of the 2010–2011 seasonal parenteral inactivated influenza vaccines marketed in the US (i.e., Afluria; CSL). The 2010 Southern Hemisphere formulation apparently induced a stronger inflammatory cytokine response than that associated with previous formulations of the vaccine or with other inactivated influenza viruses and this may have been mediated by higher concentrations of residual lipid and RNA remaining in the vaccine.

Thimerosal Precautions

Although there is no convincing evidence that the low concentrations of thimerosal (a mercury-containing preservative) contained in some vaccines is harmful to vaccine recipients, efforts to eliminate or reduce the thimerosal content in vaccines is recommended as a prudent measure to reduce mercury exposure in infants and children and part of an overall strategy to reduce mercury exposures from all sources, including food and drugs.

As a result of efforts initiated in 1999 to remove or reduce thimerosal in vaccines and expedite development and approval of preservative-free formulations of vaccines, inactivated influenza vaccine now is commercially available in prefilled single-dose syringes or single-dose vials as preservative-free formulations that do not contain thimerosal. Only multiple-dose vials of inactivated influenza virus still contain thimerosal as a preservative (≤ 25 mcg of mercury per 0.5-mL dose).

Although it was suggested that thimerosal in vaccines theoretically could have adverse effects in vaccine recipients, there is no conclusive evidence that the low levels of thimerosal contained in vaccines cause harm in vaccine recipients.

Analysis of adverse effects reported to VAERS indicates that there is no difference in the incidence of injection site reactions, rash, or infections in infants 6–23 months of age who received preservative-containing (thimerosal-containing) inactivated influenza vaccine compared with those who received preservative-free preparations of the vaccine. To date, the only adverse effects known to be caused by thimerosal contained in vaccines are local hypersensitivity reactions.

USPHS, ACIP, AAP, AAFP, and other experts state that use of vaccines that contain thimerosal is preferable to withholding vaccination since failure to provide protection against vaccine-preventable diseases may represent an immediate threat, especially in infants. AAP states that the benefits of protecting children outweigh the hypothetical risks associated with the minute amounts of thimerosal contained in some currently available influenza vaccine preparations.

Afluria (quadrivalent): Commercially available in 0.5-mL prefilled syringes as a preservative-free formulation (thimerosal not used in manufacturing process). Also available in multiple-dose vials containing thimerosal as a preservative (24.5 mcg of mercury per 0.5-mL dose).

Fluad adjuvant-containing (quadrivalent): Commercially available in 0.5-mL prefilled syringes as a preservative-free formulation that does not contain thimerosal.

Fluarix (quadrivalent): Commercially available in 0.5-mL prefilled syringes as a preservative-free formulation that does not contain thimerosal.

Flucelvax (quadrivalent): Commercially available in 0.5-mL prefilled syringes as a preservative-free formulation (thimerosal was not used in the manufacturing process). Also available in multiple-dose vials that contain thimerosal as a preservative (25 mcg of mercury per 0.5-mL dose).

Flulaval (quadrivalent): Commercially available in 0.5-mL prefilled syringes as a preservative-free formulation (thimerosal not used in manufacturing process).

Fluzone (quadrivalent): Commercially available in 0.5-mL prefilled syringes as a preservative-free formulation (thimerosal not used in manufacturing process). Also available in multiple-dose vials containing thimerosal as a preservative (25 mcg of mercury per 0.5-mL dose).

Fluzone High-Dose (quadrivalent): Commercially available in 0.7-mL prefilled syringes as a preservative-free formulation.

Individuals with Bleeding Disorders

Advise individuals and/or their family about the risk of hematoma from IM injections.

ACIP states that vaccines may be given IM to such individuals if a clinician familiar with the patient’s bleeding risk determines that the preparation can be administered with reasonable safety. In these cases, use a fine needle (23 gauge or smaller) to administer the vaccine and apply firm pressure to the injection site (without rubbing) for ≥2 minutes. In individuals receiving therapy for hemophilia, IM vaccines can be scheduled for administration shortly after a dose of such therapy.

Concomitant Illness

Base decision to administer or delay vaccination in an individual with a current or recent acute illness on severity of symptoms and etiology of the illness.

ACIP states mild acute illness does not preclude vaccination.

ACIP states moderate or severe acute illness (with or without fever) is a precaution for vaccination; defer vaccines until individual has recovered from the acute phase of the illness. This avoids superimposing vaccine adverse effects on the underlying illness or mistakenly concluding that a manifestation of the underlying illness resulted from vaccine administration.

Individuals with Known or Suspected Coronavirus Disease 2019 (COVID-19)

ACIP states defer routine vaccinations, including influenza vaccination, in symptomatic individuals with suspected or confirmed COVID-19 until criteria for discontinuance of COVID-19 isolation have been met and the individual is no longer moderately to severely ill. Consider deferring vaccination until the individual has fully recovered from the acute illness to avoid exposing health-care personnel and other patients to the disease. ACIP also states that routine vaccinations, including influenza vaccination, should be deferred in patients with mild or asymptomatic COVID-19 to avoid the inability to discern between COVID-19 symptoms and postvaccination reactions. Other considerations include the presence of risk factors for severe influenza illness and the likelihood of being able to vaccinate at a later date.

Limitations of Vaccine Effectiveness

Following seasonal influenza vaccination, up to 2 weeks may be required to develop antibody protection against infection.

May not protect all vaccine recipients against influenza.

Seasonal influenza vaccines are formulated annually to contain influenza A and B antigens predicted to represent strains of influenza virus likely to circulate in the US during the upcoming influenza season. Efficacy of seasonal influenza vaccine during any given year depends on how closely viral strains represented in the vaccine match viral strains circulating during the season.

Seasonal influenza vaccines not expected to provide protection against human infection with animal-origin influenza viruses, including avian influenza A viruses (e.g., avian influenza A [H5N1], avian influenza A [H7N9]).

Seasonal influenza vaccines will not provide protection against COVID-19.

Duration of Immunity

Duration of immunity usually <1 year. Immunity declines during the year after seasonal influenza vaccination.

Although some data indicate early vaccination (e.g., in July and August) might be associated with suboptimal immunity before end of the influenza season, particularly among older adults, revaccination later in the season not recommended for individuals who already received influenza vaccine for the current influenza season.

Annual vaccination needed because of waning immunity and because circulating strains of influenza virus change from year to year.

Do not administer influenza vaccine from a previous influenza season in an attempt to provide protection during a subsequent influenza season.

Improper Storage and Handling

Improper storage or handling of vaccines may reduce vaccine potency resulting in reduced or inadequate immune responses in vaccinees.

Inspect all vaccines upon delivery and monitor during storage to ensure that the appropriate temperature is maintained.

Do not administer vaccine that has been mishandled or has not been stored at the recommended temperature.

If there are concerns about mishandling, contact the manufacturer or state or local immunization or health departments for guidance on whether the vaccine is usable; also can consult CDC.

Specific Populations

Pregnancy

Data insufficient to assess risk of administering influenza vaccine inactivated during pregnancy.

Animal reproduction studies have not revealed evidence of harm to fetus.

Pregnant and postpartum women are at higher risk for severe influenza and influenza-related complications, particularly during the second and third trimesters, which may lead to adverse pregnancy outcomes including preterm labor and delivery.

ACIP, ACOG, and AAP recommend vaccination against influenza in all women who are pregnant or who might become pregnant during the influenza season; any licensed, age-appropriate, inactivated influenza vaccine (i.e., influenza vaccine inactivated or influenza vaccine recombinant) can be used. These experts state that inactivated influenza vaccine can be given at any time during pregnancy (any trimester) before or during the influenza season. Encourage unvaccinated postpartum women to receive vaccination before discharge from the hospital.

ACIP states that there is no evidence of risk to the fetus if inactivated vaccines are administered during pregnancy.

To monitor pregnancy outcomes and newborn health status following influenza vaccination of pregnant women, some manufacturers have established pregnancy registries. Women who receive the vaccine during pregnancy or their health-care providers may contact the manufacturer at 855-358-8966 (Afluria), 888-452-9622 (Fluarix, Flulaval), or 800-822-2463 (Fluzone).

Lactation

Not known whether influenza vaccine inactivated distributed into milk. Data insufficient to assess effects on the breast-fed infant or on milk production.

Consider benefits of breast-feeding and importance of the vaccine to the woman; also consider potential adverse effects on the breast-fed child from the vaccine or underlying maternal condition (i.e., susceptibility to influenza infection).

ACIP and AAP state breast-feeding is not a contraindication to influenza vaccine inactivated. These experts state that inactivated vaccines do not pose any unusual risks for the mother or her nursing infant.

Pediatric Use

Afluria, Fluarix, Flulaval, Fluzone, Flucelvax: Safety and efficacy not established in infants <6 months of age.

Fluad adjuvant-containing (quadrivalent): Safety and efficacy not established in pediatric patients.

Fluzone High-Dose: Safety and efficacy not established in pediatric patients.

Because seasonal influenza vaccine inactivated not indicated in infants <6 months of age, all household and other close contacts (e.g., day-care providers) of infants <6 months of age should be vaccinated against seasonal influenza using vaccine appropriate for their age and target group since this may provide some protection against seasonal influenza for these young infants.

Geriatric Use

Afluria, Fluarix, Flucelvax, Flulaval, Fluzone: No overall differences in safety relative to younger adults; may be less immunogenic in geriatric individuals.

Fluad adjuvant-containing (quadrivalent): Use only in adults ≥65 years of age. Safety profile of this standard-dose, adjuvant-containing vaccine similar to that of standard-dose, non-adjuvant-containing vaccine. Although some local and systemic adverse events reported more frequently with the adjuvant-containing vaccine, most adverse reactions have been mild in severity.

Fluzone High-Dose (quadrivalent): Use only in adults ≥65 years of age. Each 0.7 mL of Fluzone High-Dose contains 4 times the amount of antigen contained in standard-dose Fluzone. In adults ≥65 years of age, higher incidence of injection site reactions and systemic adverse effects reported with trivalent Fluzone High-Dose (no longer available in US) compared with standard-dose Fluzone. Some evidence that the high-dose formulation elicits higher antibody titers and higher seroconversion rates than the standard-dose formulation in adults ≥65 years of age and may be more effective in preventing laboratory-confirmed influenza in this age group.

ACIP states that all adults ≥65 years of age should be vaccinated against influenza using influenza virus vaccine inactivated or influenza vaccine recombinant. ACIP states a preference for Fluzone High-Dose (quadrivalent), Flublok recombinant influenza vaccine (quadrivalent), or the standard-dose quadrivalent adjuvant-containing vaccine (Fluad), but if none of these 3 vaccines are available at the time of vaccine administration, then they state that adults ≥65 years may receive a standard-dose quadrivalent preparation.

Common Adverse Effects

Injection site reactions (i.e., tenderness, pain, redness, induration, swelling), headache, fatigue, myalgia, fever, malaise.

Drug Interactions

Immunosuppressive Agents

Immune responses to vaccines, including influenza vaccine inactivated, may be reduced in individuals receiving immunosuppressive agents.

Generally, give inactivated vaccines ≥2 weeks prior to initiation of immunosuppressive therapy and, because of possible suboptimal response, do not give during and for certain periods of time after immunosuppressive therapy discontinued.

Time to restoration of immune competence varies depending on type and intensity of immunosuppressive therapy, underlying disease, and other factors; optimal timing for vaccine administration after discontinuance of immunosuppressive therapy not identified for every situation.

Vaccines

Although specific studies may not be available, concurrent administration with other age-appropriate vaccines, including live virus vaccines, toxoids, or inactivated or recombinant vaccines, during same health-care visit not expected to affect immunologic responses or adverse reactions to any of the preparations.

Immunization with influenza vaccine inactivated can be integrated with immunization against diphtheria, tetanus, pertussis, Haemophilus influenzae type b (Hib), hepatitis A, hepatitis B, human papillomavirus (HPV), measles, mumps, rubella, meningococcal disease, pneumococcal disease, poliomyelitis, rotavirus, and varicella. However, administer each parenteral vaccine using separate syringes and different injection sites.

Specific Drugs

Stability

Storage

Parenteral

Injectable Suspension, for IM Use

2–8°C; do not freeze. If freezing occurs, discard vaccine.

Return multiple-dose vials to 2–8ºC between uses. Manufacturer of Afluria states discard any vaccine remaining in multiple-dose vial after a total of 20 doses has been removed from the vial and discard multiple-dose vial if not used within 28 days after vial first entered.

Protect from light.

Single-dose syringes and single-dose vials are preservative-free. Multiple-dose vials contain thimerosal as a preservative.

Actions

• Inactivated influenza vaccines are noninfectious, sterile suspensions of suitably inactivated influenza virus types A and B subunits.

• Most seasonal inactivated influenza vaccines available in the US are split-virus preparations (i.e., contain purified subvirion or purified surface antigen) prepared from formaldehyde- or propiolactone-inactivated influenza viruses harvested from allantoic fluids of chick embryos (egg-based inactivated vaccines). An egg-based inactivated influenza vaccine that contains an adjuvant (i.e., MF59C.1) to increase antibody response also is available in the US. In addition an inactivated influenza vaccine prepared from propiolactone-inactivated influenza virus propagated in Madin Darby Canine Kidney (MDCK) cells (cell culture-based inactivated vaccine) is available in the US.

• Seasonal influenza vaccines are formulated annually to contain antigens representative of the strains of influenza A (H1N1), influenza A (H3N2), and influenza B viruses likely to circulate in the US during the upcoming influenza season.

• All inactivated influenza vaccines (egg- or cell culture-based) available in the US are quadrivalent vaccines containing 2 influenza type A antigens (H1N1 and H3N2) and 2 influenza type B antigens (B/Yamagata and B/Victoria lineages).

• Influenza vaccines stimulate active immunity to influenza virus strains represented in the vaccines.

• Efficacy of influenza vaccines in preventing seasonal influenza virus infection depends on whether the virus strains represented in the vaccines are antigenically similar to influenza virus strains circulating during the influenza season. When there is a good match between the vaccine formulation and circulating strains, a protective effect generally is achieved in 70–90% of healthy adults <65 years of age following IM administration of inactivated vaccine.

• Immune response to seasonal influenza vaccine inactivated may be lower in geriatric individuals, very young children, or individuals who are immunocompromised or have certain chronic medical conditions.

• Adults ≥65 years of age: Immunogenicity of a single dose of standard-dose adjuvant-containing quadrivalent inactivated influenza vaccine (Fluad) was demonstrated in a clinical trial.

• Adults ≥65 years of age: High-dose trivalent inactivated influenza vaccine (Fluzone High-Dose; no longer available in US) was superior to standard-dose Fluzone (trivalent; no longer available in US) for prevention of laboratory-confirmed influenza. Single-dose of Fluzone High-Dose (quadrivalent) is as immunogenic as single dose of Fluzone High-Dose (trivalent).

Advice to Patients

• Prior to administration of seasonal influenza vaccine inactivated, provide a copy of the appropriate CDC Vaccine Information Statement (VIS) to the patient or patient’s legal representative (VISs are available at [Web]).

• Advise patient and/or patient’s parent or guardian of the risks and benefits of vaccine administration.

• Advise patients that influenza vaccine inactivated contains noninfectious killed viruses and cannot cause influenza.

• Advise patients that influenza vaccine inactivated provides protection against illness due to influenza viruses represented in the vaccine and cannot provide protection against all respiratory illness.

• Advise patient and/or patient’s parent or guardian that annual vaccination against seasonal influenza is necessary.

• Importance of receiving influenza vaccine for the upcoming (current) influenza season, even if the individual received influenza vaccine for the previous influenza season.

• Advise patient and/or patient’s parent or guardian that a single dose of seasonal influenza vaccine is necessary each year in adults, adolescents, and children ≥9 years of age, but that 2 doses of seasonal influenza vaccine may be necessary in some infants and children 6 months through 8 years of age.

• Importance of informing clinicians of severe or unusual adverse effects. Clinicians or individuals can report any adverse reactions that occur following vaccination to the Vaccine Adverse Event Reporting System (VAERS) at 800-822-7967 or [Web].

• Importance of informing clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as concomitant illnesses (e.g., GBS).

• Importance of women informing clinician if they are or plan to become pregnant or plan to breast-feed.

• Importance of informing patients of other important precautionary information.

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Reload page with references included

Frequently asked questions

• How and where is a flu shot injection given?
• What flu vaccine can I use with an egg allergy?
• How well does the flu vaccine work?
• How can I get a flu vaccine without a needle?
• Where can I get the flu vaccine right now?

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Medical Disclaimer