FDA considering dividing Jynneos doses into fifths to increase vaccine supply

The Biden administration is considering splitting doses of the smallpox vaccine, which are being used to prevent monkeypox amid the current outbreak, into five smaller doses, the head of the Food and Drug Administration (FDA) said Thursday.

FDA Commissioner Robert Califf said during a briefing that his agency was looking into possible solutions to increase the number of available doses of the Jyenneos vaccine. One of these proposed solutions is dividing the current doses into fifths.

“We’re considering an approach for the current doses of Jynneos that would allow health care providers to use an existing one dose vial of the vaccine to administer a total of up to five separate doses,” Califf said. “This approach which we’re referring to as dose-sparing, would change the method of administration for Jynneos which currently administered subcutaneously.”

According to Califf, this proposed change would involve injecting the reduced Jynneos doses in between layers of skin, creating a “pocket” for the vaccine.

“There’s some advantages to intradermal administration, including an improved immune response to the vaccine,” Califf said. “It’s important to note that overall safety and efficacy profile will not be sacrificed with this approach.”

An FDA spokesperson told The Hill this change in the monkeypox vaccination strategy was being considered because it had become “clear to all of us that we would not meet current demand with the current supply.”

“As we often do at FDA, we began exploring other scientifically feasible options. The identification of a clinical study that demonstrates that this approach could work has been particularly useful in informing how this might work without sacrificing the safety and efficacy of the vaccine,” said the spokesperson.

If pursued, this new strategy would still involve two doses administered about 28 days apart.

James Krellenstein, co-founder of the LGBTQ+ healthcare advocacy group PrEP4All, noted on Twitter that the FDA’s decision appeared to based on a 2015 study that looked into the immune response derived from a one-fifth dose of Jynneos administered intradermally compared to a full dose administered subcutaneously, which is when the shot is injected into the layer of fat beneath the skin.

The study, funded in part by the National Institute of Allergy and Infectious Diseases, found that an “equivalent immune response” between the two different forms of Jynneos administration.

Krellenstein wrote he was glad to see this decision being considered, saying his organization had suggested this strategy to federal officials multiple times.