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In Hopes of Stretching Supplies, FDA Changes How Monkeypox Vaccines are Administered

The agency decided to allow for intradermal injection thus increasing the number of available doses substantially.


The FDA announced late yesterday that the agency had granted an Emergency Use Authorization (EUA) to administer the JYNNEOS vaccine by intradermal injection instead of subcutaneously. The agency said this will increase the supply by five-fold and allow more eligible people to get access to the vaccine. 

The indication for the vaccine is for individuals 18 years of age and older who are determined to be at high risk for monkeypox infection.

“In recent weeks the monkeypox virus has continued to spread at a rate that has made it clear our current vaccine supply will not meet the current demand,” FDA Commissioner Robert M. Califf, MD, said in a statement. “The FDA quickly explored other scientifically appropriate options to facilitate access to the vaccine for all impacted individuals. By increasing the number of available doses, more individuals who want to be vaccinated against monkeypox will now have the opportunity to do so.”

According to the FDA, the EUA now allows for a fraction of the JYNNEOS dose to be administered between the layers of the skin (intradermally). Two doses of the vaccine given 4 weeks apart will still be needed. They also said in the statement that there is no data available to indicate that 1 dose of this vaccine will provide long-lasting protection, which will be needed to control the current monkeypox outbreak.

The FDA said data from a 2015 clinical study of the MVA vaccine evaluated a two-dose series given intradermally compared to subcutaneously. Individuals who received the vaccine intradermally received a lower volume (one fifth) than individuals who received the vaccine subcutaneously. The results of this study demonstrated that intradermal administration produced a similar immune response to subcutaneous administration, meaning individuals in both groups responded to vaccination in a similar way.

Monkeypox incidence rates has increased dramatically with less than 50 cases reported just 2 months ago in early June to now there are 9492 confirmed cases as of yesterday, according to the Centers for Disease Control and Prevention (CDC). In recent days, the CDC has responded to these increasing number of cases by offering clinical guidance, including those with concurrent HIV and monkeypox infections.

In addition to the JYNNEOS vaccine, there is the ACAM2000 vaccine that is also licensed by the FDA for the prevention of monkeypox. The safety and immunogenicity of the former has been evaluated in people with HIV. “Clinical trials demonstrate that JYNNEOS is well-tolerated with similar immunogenicity and rates of adverse events in persons with HIV infection with CD4 cell counts of 200–750 per μL and persons without HIV infection,” investigators writing in the CDC's latest Morbidity and Mortality Weekly Report (MMWR).

“When vaccination is used for prevention of monkeypox in persons with HIV infection, JYNNEOS is preferred over ACAM2000,” the MMWR authors wrote. “Based on current recommendations from ACIP, ACAM2000 is contraindicated for persons with HIV infection because of the risk for severe adverse effects resulting from the spread of vaccinia virus.”

In another MMWR released last week, CDC discussed prioritizing specific high-risk groups for monkeypox clinical care and education.

“Public health efforts should prioritize gay, bisexual, and other men who have sex with men, who are currently disproportionately affected, for prevention and testing, address equity, and minimize stigma, while maintaining vigilance for transmission in other populations,” MMWR reported. “Clinicians should test persons with rash consistent with monkeypox, regardless of whether the rash is disseminated or was preceded by prodrome.”

In addition to the vaccines, there is a treatment, tecovirimat, which is the first-line medication recommended for people with monkeypox, including those with HIV.