Smallpox and mpox Vaccine, Live, Non-Replicating (trade name JYNNEOS) is approved by FDA for the prevention of smallpox and mpox disease in adults 18 years of age and older determined to be at high risk for smallpox or mpox infection. JYNNEOS is licensed for subcutaneous injection of 2 doses of 0.5 ml given at an interval of 28 days.
On August 9, 2022, FDA issued Emergency Use Authorization (EUA) for intradermal injection of doses of 0.1 ml as an alternative to subcutaneous injection for adults 18 years and older, similarly given as a 2-dose series at an interval of 28 days.
The JYNNEOS vaccine may be administered subcutaneously using the standard regimen (subcutaneous route (PDF)) or intradermally (intradermal route (PDF)). People of any age with a history of developing keloid scars and individuals younger than 18 years of age should receive the vaccine via the subcutaneous route. Patients with concerns about intradermal administration due to potential stigma or other personal reasons should be offered subcutaneous doses. CDC recommends that health care providers have both subcutaneous and intradermal vaccine administration options available on site so patients choose their preferred route of administration. An updated California Department of Public Health (CDPH) JYNNEOS vaccine screening (PDF) checklist (also available in Spanish (PDF)) can be used to check for a history of keloids.
Prospective vaccinees should be counseled about the possibility of redness or swelling at the site of injection after vaccination, which is a common side effect regardless of route of administration but may be more likely or prolonged in a higher proportion of vaccinees receiving intradermal doses.
As new clinical data evolves on the level of protection provided by JYNNEOS in the current outbreak, CDPH considers vaccination an important intervention to reduce severity of illness and will continue to monitor emerging data in its ongoing evaluation of its interim guidance. CDPH recommends individuals continue to also consider other preventive measures to reduce risk of mpox infection.