December 7, 2022

WASHINGTON — It seemed like a simple solution to the monkeypox vaccine shortage: By simply changing the way doses were injected, the federal government could vaccinate five times as many people as it had the supply available to it.

Experts say the approach — injecting a fifth of the current dose into the skin rather than a full dose into the essential fat — isn’t actually that simple. Some federal officials are wary of changing the method without further research, although Dr. Robert M. Califf, head of the Food and Drug Administration, called the proposal on Thursday promising.

Some outside experts also urge caution. “From a basic scientific perspective, this should work,” said Dr. J. K. Varma, director of the Cornell Center for Epidemic Prevention and Response. “But, of course, there are a lot of things in life, in science, that we think should work, and then when we actually do them, they don’t.”

Extending the doses of the vaccine, Jynneos, could help the federal government solve a partial impasse of its own making. Although it has invested more than $1 billion in developing a two-dose vaccine for use against both monkeypox and smallpox, the government has only 1.1 million injections on hand, in part because it has been slow to order large stocks of the vaccine to be processed. in vials.

That supply is enough to cover 550,000 people, but about three times the doses are needed to cover 1.6 million to 1.7 million Americans, according to the Centers for Disease Control and Prevention, who are at risk of developing monkeypox. Currently, the virus spreads primarily through skin-to-skin contact during sex between gay and bisexual men, the CDC said.

Some federal officials hope that by injecting a smaller dose of the vaccine between layers of the skin, called an intradermal injection, the Biden administration can mitigate the outbreak before it spreads more widely.

But some experts argue that this approach has not been studied enough. They also warn that some vaccinators will need to be trained to deliver the injections properly, which could slow vaccination efforts. Otherwise, the government may end up wasting the potions rather than saving them.

Intradermal injection involves carefully directing a needle into the layers of the skin, a thin area with immune cells in it. Experts say that if a pollinator goes too deep and inserts the dose into the fat, the patient may not receive enough vaccine. But if the needle is not inserted far enough, some of the vaccine may leak again.

said Dr. Phil Krause, who retired as the FDA’s chief vaccine regulator last year and worked on licensing the agency for Jynneos. “If you required it to be done nationwide in millions of doses, it would be a lot easier to make mistakes in administering the vaccine.”

On the other hand, the method has a proven track record. It was used in Polio vaccination campaigns When doses are limited, as well as for rabies and skin tests for tuberculosis.

Fauci, President Biden’s chief medical advisor, said, “It’s not a completely new concept.” “We’ve been thinking of this as a strategy in the event of a vaccine scarcity for years.”

Vaccines used special branched needles in smallpox campaigns that allowed them to perform intradermal injections more consistently and cheaply.

Dr. John Beagle, associate director of clinical research at the National Institutes of Health, said: A government-sponsored study on Jynneos published in 2015 He compared the intradermal approach with the standard injection method and found that it resulted in a similar level of neutralizing antibody, which is a measure of the strength of the immune response. The intradermal method caused more redness, swelling, and itching, but the standard injection was more painful.

Switching to an intradermal method was a better option for maintaining the vaccine than giving just a single injection, as some jurisdictions now do, Dr. Beagle said, because research has shown that a single dose almost does not stimulate a strong immune response.

“It is unlikely that a single dose will be effective,” he said, adding that the intradermal method is an “acceptable method of use.”

Although the 2015 trial included hundreds of participants, some experts note that it was a single study that was limited in what was measured. Researchers at the National Institutes of Health were planning to test an intradermal strategy for Genius in trial It was due to start in a few weeks. But the results weren’t expected until late fall or early winter, and that plan is up in the air for now.

Dr. H. Clifford Lane, clinical director of the Dr. Fauci National Institute of Allergy and Infectious Diseases at the National Institutes of Health, said that while researchers can glean insight by following vaccinated people, a traditional clinical trial will provide a clearer picture.

“I can understand doing it as long as it’s very clear why you’re doing it,” he said of the intradermal strategy. “The question is: How can we expand existing supplies without compromising efficacy significantly?”

Another question is how well the vaccine will actually work: It was licensed in 2019 for use against both monkeypox and smallpox after studies showed it elicited a stronger immune response than a previous vaccine. Federal officials said this same drug has been approved because it compares favorably with an earlier vaccine.

Monkeypox is rarely fatal and no deaths have been reported in the United States. Symptoms usually resolve within two to four weeks. But with an outbreak of the disease from eight cases reported in late May to 7,510 nowThe administration is striving to improve the vaccination rate and availability of tests and treatments.

As of now, the outbreak is almost entirely restricted to men who have sex with men, with those with multiple partners considered to be at particular risk. But five cases involving children have been reported so far. On Friday, the Illinois Department of Public Health announced that an adult working at a daycare center had tested positive for monkeypox and that children and other staff there were being tested.

Thursday’s declaration of a public health emergency allowed the federal government to speed up monkeypox investigations and approve grants, but it did not appeal to the Food and Drug Administration’s emergency powers. Changing the injection position requires a second type of emergency Advertisinggiving the Food and Drug Administration more freedom to issue emergency use authorizations.

Federal regulators can issue emergency permits for products when they believe the potential benefits outweigh the potential risks. Early in the coronavirus pandemic, the Trump administration issued the same type of emergency declaration, allowing the Food and Drug Administration to make Covid-19 vaccines available to Americans several months before regulators issued full approvals.

Dr. Califf, commissioner of the Food and Drug Administration, said Thursday that regulators will continue to ensure the vaccine is delivered in a safe and effective manner. He said regulators will likely decide in the next few days whether to pursue an intradermal strategy, but it “looks good now” – a comment that some outside experts said appeared to predate the deliberations of professional regulators.

Emily Cochran and Tracy Tully contributed reporting.

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