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Generic name: smallpox and monkeypox vaccine
Drug class: Viral vaccines

Medically reviewed by Judith Stewart, BPharm. Last updated on Aug 22, 2022.

What is Jynneos?

Jynneos is used to help prevent smallpox and monkeypox diseases.

Like any vaccine, Jynneos may not provide protection from disease in every person.

Jynneos is for use in adults 18 years of age and older who are determined to be at high risk of contracting smallpox or monkeypox infection.

Jynneos is also authorized for emergency use to prevent monkeypox disease in people younger than 18 years of age who are determined to be at high risk of monkeypox infection.


Use Jynneos only as directed. Tell your doctor if you use other medicines or have other medical conditions or allergies.

Jynneos can cause a severe allergic reaction. Medical treatment must be available to treat any anaphylactic reactions following administration.

Immunocompromised persons, including those receiving immunosuppressive therapy, may have a diminished immune response to this vaccine.

Vaccination with Jynneos may not protect all patients.

Before taking this medicine

You should not receive Jynneos if you have ever had a life-threatening allergic reaction to a smallpox or monkeypox vaccine.

Tell your doctor if you have a weak immune system caused by receiving certain medicines such as steroids, chemotherapy or radiation.

Tell your doctor if you are pregnant or breastfeeding.

How is Jynneos given?

Jynneos is injected under the skin (subcutaneous injection), preferably into the upper arm. You will receive this vaccine in a doctor's office, clinic setting, or pharmacy.

Jynneos is also authorized by the FDA for emergency use as a smaller dose for administration between the layers of skin (intradermal injection) to increase available vaccine doses in order to meet increased demand during a public health emergency.

Jynneos is administered in two doses 4 weeks apart. Talk with your doctor if you had a severe reaction after the first dose.

Your doctor or pharmacist can provide more information about this vaccine. Additional information is available from your local health department or the Centers for Disease Control and Prevention.

Dosing information

Usual Adult Dose for Prevention of Smallpox and Monkeypox:

Standard Regimen: Two subcutaneous doses of 0.5 mL each, 4 weeks apart.

Use: Prevention of smallpox and monkeypox disease in adults 18 years or older at high risk of infection.

Alternative Regimen (Emergency Use Authorization): Two intradermal doses of 0.1 mL each, 4 weeks apart (used to increase supply of vaccine doses during a public health emergency).

Use: Prevention of monkeypox disease in adults 18 years or older at high risk of infection.

Usual Pediatric/Adolescent Dose for Prevention of Monkeypox:

Standard Regimen (Emergency Use Authorization): Two subcutaneous doses of 0.5 mL each, 4 weeks apart. 

Use: Prevention of monkeypox disease in people younger than 18 years at high risk of infection.

What happens if I miss a dose?

Be sure you receive all recommended doses of Jynneos. You may not be fully protected against disease if you do not receive the full series.

What happens if I overdose?

Since this vaccine is given by a healthcare professional, an overdose is unlikely to occur.

What should I avoid while receiving Jynneos?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Jynneos side effects

Get emergency medical help if you have signs of an allergic reaction to Jynneos: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Common Jynneos side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report vaccine side effects to the US Department of Health and Human Services at 1 800 822 7967.

What other drugs will affect Jynneos?

Before receiving Jynneos, tell the doctor about all other vaccines you have recently received.

Also tell the doctor if you have recently received drugs or treatments that can weaken the immune system, including:

This list is not complete. Other drugs may interact with Jynneos, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Jynneos only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.