In a letter Friday to Bavaria Nordic CEO Paul Chaplin, two senior FDA officials responded to concerns Chaplin had raised earlier this week. They wrote that the agency recently determined that the benefits of extending its limited supply of the two-dose Jynneos vaccine by giving individuals smaller doses outweigh the known potential risks.
The decision came after the FDA ruled out, at least for now, the use of alternative vaccines, as well as the option of delaying the second dose of the vaccine by three to six months, the agency said.
The FDA letter, obtained by CNN on Saturday, was signed by FDA Commissioner Dr. Robert Califf, and Dr. Peter Marks, the director of the FDA’s Center for Biologics Research and Evaluation.
The letter cited a 2015 clinical study, which Chaplin co-authored, in which “individuals who received the vaccine intradermally received a lower volume (one-fifth) than individuals who received the vaccine via subcutaneous”.
“The results of this study showed that intradermal administration produced an immune response very similar to subcutaneous (SC) administration,” the letter said. Although the intradermal injection method “resulted in more redness, firmness, itching, and swelling at the injection site, but less pain,” the letter continued, “these side effects were manageable.”
The FDA also detailed other options the agency had considered. But the use of alternative vaccines to prevent smallpox “was determined to be impractical or inadvisable at this time,” according to the letter. Specifically, the ACAM2000 vaccine, which is FDA-approved for the prevention of smallpox, “may not be appropriate now for a potentially immunocompromised population,” the letter said.
The FDA also considered delaying the second vaccine doses by three to six months, rather than giving the second dose the recommended 28 days after the first.
But the agency ultimately determined that there was no data to show that this method would provide sufficient protection, and that delaying the second dose could also give people “a false sense of reassurance that they were protected against monkeypox when the actual level of protection would be”. be unknown and quite possibly inappropriate,” the letter said.
The federal government’s announcement this week that it is authorizing health care providers to give smaller doses of Jynneos came in an attempt to better meet high demand for the vaccine. Top health officials in the Biden administration have made clear in recent days that given the speed of the spread of monkeypox, which was declared a public health emergency earlier this month, the US did not have enough supply of vaccines to meet demand. This week’s decision to extend the available Jynneos vaccines was aimed at addressing the limited supply.
The FDA’s Dr. Marks said Thursday that there were 1.6 to 1.7 million people in the US who are now eligible for the two-dose Jynneos vaccine. According to the US Department of Health and Human Services, about 634,213 vials were sent to jurisdictions on Friday.
The low-dose intradermal strategy immediately raised concerns from some public health experts, including the limited amount of research surrounding the new method.
“This approach raises red flag after red flag and appears to be moving forward without data on efficacy, safety, or alternative dosing strategies,” David Harvey, executive director of the National Coalition of STD Directors, said in a statement this week. week
Chaplin, the CEO of Bavarian Nordic, also expressed concern. CNN reported that Chaplin wrote in a letter to Califf and HHS Secretary Xavier Becerra on Tuesday that he was concerned about the “very limited safety data available” on the recently announced vaccination strategy and that a relatively high percentage of people in the clinical study: 20% did not get a second chance.
“Although we have certain reservations, we are trying to find the best way to support [emergency use authorization] gathering additional data and aligning responses to assist state officials in deployment,” Chaplin wrote. “We are also investing in expanding manufacturing capacity at both BN facilities and offsite, with likely more announcements coming soon.”