Influenza Vaccine Live Intranasal (Monograph)

Brand name: FluMist
Drug class: Vaccines

Medically reviewed by Drugs.com on Dec 10, 2024. Written by ASHP.

Introduction

Live, attenuated virus vaccine.¹ Seasonal influenza vaccine live intranasal (LAIV) contains live (cold-adapted) influenza virus types A and type B representing influenza strains likely to circulate in the US during the upcoming season and is used to stimulate active immunity to influenza strains contained in the vaccine.^{1 100}

Uses for Influenza Vaccine Live Intranasal

Prevention of Seasonal Influenza A and B Virus Infections

Used to stimulate active immunity for prevention of disease caused by influenza virus subtypes A and B represented in the vaccine; FDA-labeled for use in individuals 2 through 49 years of age.¹

Has not been evaluated in individuals with altered immunocompetence.¹ The US Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) recommends that live attenuated influenza vaccine not be used for immunocompromised persons because of the uncertain but biologically plausible risk for disease attributable to the live vaccine virus.¹⁰⁰

Annual vaccination is the primary means of preventing seasonal influenza and its complications.¹⁰⁰

ACIP and the American Academy of Pediatrics (AAP) provide recommendations and guidance for vaccination providers regarding the use of influenza vaccines in the US.^{100 112} These experts recommend routine influenza vaccination in all persons ≥6 months of age who do not have contraindications.^{100 112}

Seasonal influenza vaccination is particularly important for individuals at increased risk for severe influenza or influenza-related complications and those who live with or care for such individuals (e.g., health-care personnel, household or other close contacts).¹⁰⁰

All influenza vaccines available in the US for the 2024-25 season are trivalent formulations containing antigens representing influenza A (H1N1), influenza A (H3N2), and influenza B (Victoria lineage).¹⁰⁰ For the 2024–25 influenza season, the influenza vaccine composition no longer includes influenza B/Yamagata because there have been no confirmed detections of influenza B/Yamagata viruses in global influenza surveillance since March 2020.¹⁰⁰

Various preparations of influenza virus vaccines are commercially available in the US.¹⁰⁰ The vaccines can be grouped into 3 broad categories: inactivated influenza vaccines (IIV), recombinant influenza vaccine (RIV3), and live attenuated virus vaccine (LAIV3).¹⁰⁰ Inactivated influenza vaccines (IIV3) include standard-dose egg-based vaccines, a standard-dose cell culture-based influenza vaccine (ccIIV3), a high-dose egg-based vaccine (HD-IIV3), and an adjuvanted standard-dose egg-based vaccine (aIIV3).¹⁰⁰

ACIP states that all persons ≥6 months of age should receive an age-appropriate influenza vaccine with the exception of solid organ transplant recipients 18–64 years of age who are receiving immunosuppressive medication regimens; these individuals may receive either high-dose inactivated influenza vaccine (HD-IIV3) or adjuvanted inactivated influenza vaccine (aIIV3) as acceptable options (without a preference over other age-appropriate IIV3s or RIV3).¹⁰⁰

Because influenza vaccines are often less effective in older adults, the higher dose vaccines or adjuvanted vaccine is recommended in this population.¹⁰⁰ For the 2024-25 influenza season, ACIP recommends that adults ≥65 years preferentially receive trivalent high-dose inactivated influenza vaccine (HD-IIV3), trivalent recombinant influenza vaccine (RIV3), or trivalent adjuvanted inactivated influenza vaccine (aIIV3).¹⁰⁰ If none of these vaccines is available at an opportunity for vaccine administration, then any other age-appropriate influenza vaccine should be used.¹⁰⁰

With regard to timing of vaccine, for most individuals who need only 1 dose of influenza vaccine for the season, ACIP recommends that healthcare providers ideally offer influenza vaccination during September or October.¹⁰⁰ However, vaccination should continue after October and throughout the influenza season as long as influenza viruses are circulating and unexpired vaccine is available.¹⁰⁰ For most adults, vaccination during July and August generally should be avoided unless there is a concern that vaccination during the season might not be possible; however, vaccination during these months can be considered in children who require 2 doses, children who require only 1 dose but visit their healthcare provider during late summer before the start of the school year, and pregnant persons in the third trimester.¹⁰⁰

Influenza Vaccine Live Intranasal Dosage and Administration

General

Pretreatment Screening

• Screen all individuals for contraindications and precautions to vaccination.^{100 112}

Dispensing and Administration Precautions

• Appropriate medical treatment must be immediately available to manage potential anaphylactic reactions following administration of influenza vaccine live intranasal.¹

Administration

Intranasal Administration

Administer intranasally using prefilled, single-use sprayer supplied by the manufacturer.¹

The single-use sprayer is equipped with a nozzle that produces a fine mist that is primarily deposited in the nose and nasopharynx.¹

Influenza vaccine live intranasal is a colorless to pale yellow suspension and is clear to slightly cloudy.¹ Do not mix with any other vaccine or solution.¹³⁴

May be self- or caregiver-administered for those who meet eligibility criteria or be administered by a healthcare provider.²

Place recipient in an upright position.¹ Administer approximately one-half the contents of the prefilled, single-use sprayer into each nostril.¹ Active inhalation (i.e., sniffing) by patient not required.¹ Consult manufacturer’s labeling for specific information regarding use of the sprayer.¹

Some experts state the vaccine dose does not need to be repeated if patient coughs or sneezes immediately after receiving the intranasal vaccine.^{100 134} Do not administer to individuals who have nasal congestion that might impede delivery of the vaccine to nasopharyngeal mucosa.^{100 112}

After administering vaccine, carefully dispose of the sprayer (i.e., discard using standard procedures for medical waste).¹

May be given simultaneously with other age-appropriate vaccines during same health-care visit.¹³⁴

Dosage

Dosing schedule (i.e., number of doses) for prevention of seasonal influenza depends on individual’s age and vaccination history.¹

A single dose consists of the entire contents (0.2 mL) of the sprayer (approximately one-half of the contents or 0.1 mL in each nostril).¹

Pediatric Patients

Prevention of Seasonal Influenza A and B Virus Infections

Healthy Children 2 through 8 Years of Age

Intranasal

Did not receive a total of 2 or more doses of any seasonal influenza vaccine before July 1, 2024 or whose previous influenza vaccination history is unknown: Administer 2 doses of influenza vaccine live intranasal at least 4 weeks apart.^{1 100} Each dose consists of 0.2 mL (0.1 mL in each nostril).¹ For children 8 years of age who require 2 doses of the vaccine, both doses should be administered even if the child turns 9 years between receipt of dose 1 and dose 2.¹⁰⁰

Healthy children 2 through 8 years of age who received a total of 2 or more doses of any seasonal influenza vaccine ≥4 weeks apart before July 1, 2024: Administer a single dose of influenza vaccine live intranasal consisting of 0.2 mL (0.1 mL in each nostril).^{1 100}

Healthy Children and Adolescents 9 through 17 Years of Age

Intranasal

Single dose consisting of 0.2 mL (0.1 mL in each nostril).^{1 100}

Adults

Prevention of Seasonal Influenza A and B Virus Infections

Healthy, Nonpregnant Adults 18 through 49 Years of Age

Intranasal

Single dose consisting of 0.2 mL (0.1 mL in each nostril).^{1 100}

Special Populations

Geriatric Patients

Not indicated in adults ≥50 years of age, including geriatric adults.¹

Cautions for Influenza Vaccine Live Intranasal

Contraindications

• History of severe allergic reaction (e.g., anaphylaxis) to any component of the vaccine, including egg protein.¹

• History of severe allergic reaction (e.g., anaphylaxis) to previous dose of any influenza vaccine.¹

• Children and adolescents 2 through 17 years of age receiving aspirin or aspirin-containing therapy; possible association of Reye’s syndrome with aspirin use and wild-type influenza infection.¹

Warnings/Precautions

Risks in Children <24 Months of Age

Do not use in infants <24 months of age; increased risk of wheezing and hospitalization reported in clinical trials in this age group.¹

Individuals with Asthma, Recurrent Wheezing, or Active Wheezing

Individuals of any age with asthma and children <5 years of age with history of recurrent wheezing may be at increased risk of wheezing after receiving influenza vaccine live intranasal.¹

Influenza vaccine live intranasal has not been studied in individuals with severe asthma or active wheezing.¹

ACIP states to not use influenza vaccine live intranasal in children 2 through 4 years of age diagnosed with asthma and use with caution in individuals ≥5 years of age diagnosed with asthma.¹⁰⁰ ACIP also states do not use in children 2 through 4 years of age if the parent or caregiver states that a health-care provider told them during the preceding 12 months that the child had wheezing or asthma or if the child’s medical record indicates a wheezing episode occurred during the preceding 12 months.¹⁰⁰

AAP states to not use influenza vaccine live intranasal in children diagnosed with asthma.¹¹² AAP also states do not use in children 2 through 4 years of age with a history of recurrent wheezing or a medically attended wheezing episode during the previous 12 months because of potential for increased wheezing after receipt of the vaccine.¹¹² When considering use in children 24 through 59 months of age, AAP recommends asking the parent or caregiver if the child had any wheezing during the previous 12 months; if there is such a history, use age-appropriate parenteral influenza virus vaccine inactivated (not influenza vaccine live intranasal) in such children.¹¹²

Guillain-Barré Syndrome (GBS)

If GBS has occurred within 6 weeks after previous influenza vaccination, the decision to administer influenza vaccine should be based on careful consideration of potential benefits and risks.¹

The 1976 swine influenza vaccine was associated with increased frequency of GBS.¹ 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.¹

ACIP states that a history of GBS within 6 weeks after receipt of any influenza vaccine is a precaution to the use of all influenza vaccines.¹⁰⁰

Individuals with Altered Immunocompetence

Manufacturer states efficacy of influenza vaccine live intranasal not studied in immunocompromised individuals.¹

Use of live, attenuated virus vaccines in individuals with altered immunocompetence may be associated with increased risk for adverse reactions because of uninhibited growth of the live, attenuated vaccine virus.^{100 134 135} In addition, immune responses to vaccines may be reduced in immunosuppressed individuals.^{100 134 135}

ACIP states that influenza vaccine live intranasal should not be used in children and adults who are immunocompromised, including but not limited to immunosuppression caused by medications, congenital or acquired immunodeficiency states, HIV infection, anatomic asplenia, or functional asplenia such as that due to sickle cell anemia.¹⁰⁰

Because of possible transmission of live vaccine viruses, ACIP also states that influenza vaccine live intranasal should not be administered to close contacts of severely immunocompromised individuals who require care in a protective environment (e.g., hematopoietic stem cell transplant [HSCT] recipients within 2 months after transplant or with graft-versus-host disease [GVHD], individuals with severe combined immune deficiency [SCID]).^{100 134}

Individuals with Medical Conditions Involving CSF Leak

ACIP states do not use influenza vaccine live intranasal in individuals with medical conditions that involve active communication between CSF and the oropharynx, nasopharynx, nose, or ear or any other cranial CSF leak.¹⁰⁰ In addition, ACIP states do not use the live vaccine in individuals with cochlear implants because of potential for CSF leak, which might exist for some period after implantation.¹⁰⁰

Individuals with Medical Conditions that Increase Risk of Influenza Complications

Safety not established in individuals with underlying medical conditions that increase risk for complications following wild-type influenza infection.¹

ACIP states do not use influenza vaccine live intranasal in individuals with chronic pulmonary, cardiovascular (except isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus).¹⁰⁰

Transmission of Vaccine Virus

Influenza vaccine live intranasal contains live, attenuated virus.¹ Vaccine virus capable of infection and replication is present in nasal secretions of vaccine recipients and viral shedding occurs in adults and children who have received the live intranasal vaccine.¹

Transmission of vaccine virus has occurred rarely between recipients of influenza vaccine live intranasal and their contacts.¹

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.¹³⁴

ACIP states mild acute illness does not preclude vaccination.¹³⁴

ACIP states moderate or severe acute illness (with or without fever) is a precaution for vaccination;¹³⁴ defer vaccines until individual has recovered from the acute phase of the illness.¹³⁴ This avoids superimposing vaccine adverse effects on the underlying illness or mistakenly concluding that a manifestation of the underlying illness resulted from vaccine administration.¹³⁴

ACIP and AAP state defer administration of influenza vaccine live intranasal if nasal congestion is present that might impede delivery of the intranasal vaccine to nasopharyngeal mucosa;^{100 112} alternatively, use a different age-appropriate influenza vaccine.¹⁰⁰

Hypersensitivity Reactions

Hypersensitivity reactions (e.g., anaphylactic reaction, facial edema, urticaria) reported.¹ Contraindicated in individuals who have experienced a severe allergic reaction (e.g., anaphylaxis) to any component of the vaccine including egg protein, or after a previous dose of any influenza vaccine.¹

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.^{100 112 134}

Appropriate medical treatment and supervision must be readily available in case anaphylaxis occurs.¹

Although egg is a component of influenza vaccine live intranasal, ACIP states that all individuals 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.¹⁰⁰ 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.¹⁰⁰ All vaccines should be administered in settings in which personnel and equipment needed for rapid recognition and treatment of acute hypersensitivity reactions are available.¹⁰⁰ Although egg allergy is neither a contraindication nor precaution to the use of any influenza vaccine, there are contraindications and precautions related to allergies to vaccine components other than egg and to previous allergic reactions to influenza vaccines.¹⁰⁰

Limitations of Vaccine Effectiveness

May not protect all vaccine recipients from influenza.¹

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.^{1 100} 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.¹⁰⁰

Specific Populations

Pregnancy

Manufacturer states influenza vaccine live intranasal not absorbed systemically following intranasal administration and use in pregnant women not expected to result in fetal exposure.¹ Animal reproduction studies have not revealed evidence of harm to the fetus.¹

Experts state to not use influenza vaccine live intranasal in pregnant women.^{100 112} Women who are pregnant or who might become pregnant during the influenza season should be vaccinated using any licensed, age-appropriate, inactivated influenza vaccine (i.e., influenza virus vaccine inactivated or influenza vaccine recombinant).^{100 112}

Lactation

Manufacturer states influenza vaccine live intranasal not absorbed systemically following intranasal administration and distribution into milk not expected.¹

ACIP states that live, attenuated virus vaccines generally do not pose any unusual risks for women who are breast-feeding or their breast-fed infants.¹³⁴ Although live vaccine viruses can replicate in the mother, the majority of live vaccine viruses are not distributed into milk.¹³⁴

Pediatric Use

Safety and efficacy established only in children ≥2 years of age.¹

Effectiveness of influenza vaccine live intranasal in children 6 years–17 years of age is supported by demonstration of efficacy in younger children 6–71 months of age and effectiveness in adults 18–49 years of age.¹

Not indicated in infants <24 months of age.¹ Increased incidence of wheezing and hospitalization reported in a clinical trial in infants 6 through 23 months of age^{† [off-label]} who received influenza vaccine live intranasal compared with those who received parenteral influenza virus vaccine inactivated.¹

ACIP states do not use in children 2 through 4 years of age with asthma and use with caution in children ≥5 years of age with asthma.¹⁰⁰ AAP states do not use in any child with asthma.¹¹² Both ACIP and AAP state do not use in certain children with a history of wheezing.¹⁰⁰

Protection of young infants against seasonal influenza virus depends on immunization of their close contacts.^{100 112} All household contacts, health-care and day-care providers, and other close contacts of young infants should receive seasonal influenza vaccination appropriate for their age and target group.^{100 112}

Adults 50–64 Years of Age

Not indicated for use in adults 50–64 years of age.¹ Efficacy not demonstrated in adults 50–64 years of age.¹

Geriatric Use

Not indicated for use in geriatric individuals ≥65 years of age.¹

Common Adverse Effects

Children 2 through 6 years of age: Runny nose/nasal congestion, decreased appetite, irritability, lethargy, sore throat, fever, headache, muscle aches, chills.¹

Older children and adolescents through 17 years of age: Adverse effects similar to those reported in younger children; in addition, abdominal pain and decreased activity.¹

Adults 18 through 49 years of age: Runny nose, headache, sore throat, tiredness/weakness, muscle aches, cough, chills, nasal congestion, sinusitis.¹

Drug Interactions

Immunosuppressive Agents

Immune responses to vaccines may be reduced in individuals receiving immunosuppressive therapy.^{100 134} In addition, increased risk of adverse effects if live, attenuated virus vaccines used in individuals receiving immunosuppressive therapy.^{100 134}

Generally give live, attenuated virus vaccines ≥2–4 weeks before initiation of immunosuppressive therapy and do not give during and for certain periods of time after immunosuppressive therapy discontinued.^{100 105 134}

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.¹⁰⁵

Vaccines

Influenza vaccine live intranasal can be administered concurrently with or at any interval before or after inactivated vaccines or toxoids.¹³⁴

Influenza vaccine live intranasal and other live vaccines generally may be administered concurrently on the same day.^{100 134} However, because of theoretical concerns that immune responses to other live virus vaccines might be impaired if given within 4 weeks (28 days) of another live virus vaccine, ACIP states that if influenza vaccine live intranasal and other live vaccines are not given on the same day, give ≥4 weeks apart.^{100 134} If another live vaccine is given <4 weeks after a previous live vaccine, ACIP states repeat the dose of the second live vaccine ≥4 weeks later.¹³⁴

Specific Drugs

Stability

Storage

Intranasal Spray

Suspension

2–8°C; do not freeze.¹

A single temperature excursion up to 25°C for 12 hours has no adverse impact on the vaccine; however, after such an excursion, immediately return the vaccine to 2–8°C and use as soon as feasible.¹ Subsequent excursions not permitted.¹

Does not contain thimerosal or any other preservatives.¹

Actions

• Influenza vaccine live intranasal contains live, attenuated (cold-adapted) influenza virus types A and type B.¹ The vaccine is prepared by culturing live attenuated influenza virus reassortants in specific pathogen-free eggs.¹

• Seasonal influenza vaccines are formulated annually to contain antigens representative of the influenza A (H1N1), influenza A (H3N2), and influenza B virus likely to circulate during the upcoming influenza season.^{1 100}

• Influenza vaccines stimulate active immunity to influenza virus strains represented in the vaccines.¹

• Following administration of influenza vaccine live intranasal, vaccine virus replicates in cells lining the nasopharynx.¹ Protective mechanism not completely understood; may involve both serum and nasal secretory antibodies and cell-mediated immune responses (influenza-specific T-cells).¹

• 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.¹⁰⁰

Advice to Patients

• Prior to administration of seasonal influenza vaccine live, provide a copy of the appropriate CDC Vaccine Information Statement (VIS) to the patient or patient’s legal representative.^{1 20}

• Advise patient and/or patient’s parent or guardian of the risks and benefits of influenza vaccine live intranasal.¹

• Advise patient and/or patient’s parent or guardian that annual vaccination against seasonal influenza is necessary.¹⁰⁰ Stress importance of receiving influenza vaccine for the upcoming (current) influenza season even if the individual received influenza vaccine for the previous influenza season.^{100 112}

• 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 children 2 through 8 years of age.^{1 100 112}

• Ask patient and/or patient’s parent or guardian if vaccinee has a history of asthma or recurrent wheezing.¹ Advise patient’s parent or guardian that a history of recurrent wheezing may be an asthma equivalent in children <5 years of age and that individuals of any age with asthma and children <5 years of age with recurrent wheezing may be at increased risk for wheezing after receiving the intranasal vaccine.¹

• Advise patient and/or patient’s parent or guardian that seasonal intranasal influenza vaccine is a live, attenuated virus vaccine and that vaccine virus can be transmitted to immunocompromised close contacts.¹

• Inform clinicians of adverse effects.¹ Clinicians or individuals can report any adverse reactions that occur following vaccination to the manufacturer at 877-633-4411 or Vaccine Adverse Event Reporting System (VAERS) at 800-822-7967 or [Web].¹

• Stress importance of informing clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as concomitant illnesses (i.e., asthma, recurrent wheezing, GBS).¹

• Stress importance of women informing clinician if they are or plan to become pregnant or plan to breast-feed.¹

• Inform patients of other important precautionary information.¹

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.

Medical Disclaimer