“The outcomes of this examine demonstrated that intradermal administration produced a really related immune response to subcutaneous (SC) administration,” the letter mentioned. Whereas the intradermal injection technique “did lead to extra redness, firmness, itchiness and swelling on the injection web site, however much less ache,” the letter continued, “these uncomfortable side effects had been manageable.”

The FDA additionally detailed different choices that the company had thought of. However using different vaccines to stop monkeypox “was decided to be both impractical or inadvisable at the moment,” in keeping with the letter. Particularly, the ACAM2000 vaccine, which is FDA permitted for prevention of smallpox, “might not be acceptable now for a doubtlessly immunocompromised inhabitants,” the letter mentioned.

The FDA additionally appeared into the choice of delaying the second vaccine doses by three to 6 months, reasonably than giving the second dose the really useful 28 days after the primary.

However the company in the end decided that there was not any information to display that this technique would supply enough safety, and that delaying the second dose may additionally give individuals “a false sense of reassurance that they had been protected towards monkeypox when the precise degree of safety could be unknown and fairly probably insufficient,” the letter mentioned.

Dr. Marks of the FDA mentioned Thursday that there have been an estimated 1.6 million to 1.7 million individuals within the US who are actually eligible for the two-dose Jynneos vaccine. Based on the US Division of Well being and Human Providers, round 634,213 vials have been despatched to jurisdictions as of Friday.

The low-dose intradermal technique instantly prompted concern amongst some public well being specialists, together with in regards to the restricted quantity of analysis surrounding the brand new technique.

“This method raises pink flag after pink flag, and seems to be rushed forward with out information on efficacy, security, or different dosing methods,” David Harvey, government director of the Nationwide Coalition of STD Administrators, mentioned in an announcement this week.

Chaplin, the CEO of Bavarian Nordic, additionally raised considerations. CNN reported that Chaplin wrote in a letter Tuesday to Califf and HHS Secretary Xavier Becerra that he had considerations in regards to the “very restricted security information out there” on the newly introduced vaccination technique, and {that a} comparatively excessive proportion of individuals within the medical examine — 20% — didn’t get their second shot.

“Whereas we have now sure reservations, we’re looking for the easiest way to help the [emergency use authorization] by amassing further information and aligning on the responses to help state officers within the rollout,” Chaplin wrote. “We’re additionally investing in increasing the manufacturing capability at each BN and exterior services, with possible extra bulletins quickly to return.”