April 1, 2023

WASHINGTON — This sounds like an easy solution to the monkeypox vaccine shortage: Just by changing the way the dose is given, the federal government could vaccinate people with five times the supply on hand.

But experts say the approach — injecting one-fifth of the current dose into the skin instead of the full dose into the underlying fat — isn’t actually that simple. Some federal officials are concerned about changing the approach without more research, though FDA Commissioner Dr. Robert Califf said Thursday that the proposal is promising.

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

Extending the dose of the vaccine Jynneos could help the federal government address part of its own woes. Although it has invested more than $1 billion to develop a two-dose vaccine against monkeypox and smallpox, the government has only 1.1 million doses on hand, in part because ordering bulk vaccine stocks to be processed into vials has been slow.

That supply is enough to cover 550,000 people, but according to the Centers for Disease Control and Prevention, roughly three times the dose would be needed to cover the 1.6 million to 1.7 million Americans at high risk for monkeypox. Currently, the virus is spread primarily through skin-to-skin contact between gay and bisexual men during sex, the CDC said.

Some federal officials hope that by injecting smaller doses of the vaccine, known as intradermal injections, between layers of the skin, a Biden administration can contain the outbreak before it spreads more widely.

But some experts believe this approach has not been fully studied. They also warned that some vaccinators would need to be trained to properly vaccinate, which could slow down vaccination efforts. Otherwise, the government could end up wasting doses instead of saving them.

Intradermal injections involve carefully guiding the needle into the layer of skin, a thin space with immune cells. If the injector goes too deep and inserts the dose into the fat, patients may not get enough vaccine, experts say. But if the needle is not inserted far enough, some vaccines could leak out.

“If you’re giving a lower dose and you’re not injecting it into the skin correctly – you may be injecting it in the wrong place – you may not be giving a protective vaccine,” said Dr Phil Krauss, a retired Last year, the FDA’s top vaccine regulator was responsible for the agency’s licensing of Jynneos. “If you’re asking for millions of doses across the country, it’s more prone to error in the vaccination process.”

On the other hand, this method has a good track record.it has been used Polio vaccination campaign When the dose is limited, and for rabies and tuberculosis skin tests.

“This is not an entirely new concept,” said Dr. Anthony Fauci, President Biden’s top medical adviser. “We considered this a few years ago as a strategy to deal with the lack of a vaccine.”

Vaccinators used special bifurcated needles in smallpox campaigns, which allowed them to deliver intradermal injections more uniformly and cheaper.

Dr. John Berger, associate director of clinical research at the National Institutes of Health, said: Government-funded Jynneos study published in 2015 The intradermal method was compared to the standard injection method and found that it triggered comparable levels of neutralizing antibodies, a measure of the strength of the immune response. Intradermal injections cause more redness and itching, but standard injections are more painful.

Dr Berger said switching to the intradermal method was a better option for preserving the vaccine, rather than just a single shot, as some jurisdictions are doing now, as studies have shown that a single shot does not elicit nearly as strong immunity reaction.

“One dose is unlikely to be effective,” he said, adding that the intradermal approach “is an acceptable approach.”

Although the 2015 trial involved hundreds of participants, some experts noted that it was a single study with a limited range of measurements. NIH researchers have been planning to test Jynneos’ intradermal strategy trial This will start in a few weeks. But results won’t come until late fall or early winter, and the plan is still up in the air.

Dr. H. Clifford Lane, clinical director of the National Institute of Allergy and Infectious Diseases at the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, said that while researchers can gather insight by tracking vaccinated people, traditional clinical trials provide a clearer picture. screen.

“As long as it’s very clear why it’s being done, I can understand it,” he said of the intradermal strategy. “The question is: How can we extend the existing supply without significantly compromising efficacy?”

Another question is how well the vaccine actually works: It was licensed for use against monkeypox and smallpox in 2019 after studies showed it elicited a stronger immune response than earlier vaccines. Federal officials said the drug itself was approved because of its advantages over earlier vaccines.

Monkeypox is rarely fatal, and no deaths have been reported in the United States. Symptoms usually subside within two to four weeks.But as the outbreak surged from eight reported cases in late May to 7,510 nowthe government is scrambling to try to increase vaccination rates and the availability of tests and treatments.

As of now, the outbreak has been almost exclusively limited to men who have sex with men, and those with multiple partners are considered particularly at 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 day care center had tested positive for monkeypox and that children and other staff were being screened. check.

The public health emergency declared Thursday allowed the federal government to expedite a monkeypox investigation and approve funding, but did not invoke the FDA’s emergency powers.Changing injection mode requires a second emergency declarationgiving the Food and Drug Administration more room to issue emergency use authorizations.

Federal regulators can issue emergency authorizations 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 FDA to provide Americans with a Covid-19 vaccine months before full regulatory approval.

FDA Commissioner Dr. Califf said Thursday that regulators will continue to ensure that vaccines are delivered in a safe and effective manner. He said the regulator could decide in the coming days whether to adopt an intradermal strategy, but it “looks good right now” – a comment that some outside experts said appeared to be ahead of the occupation regulator’s deliberations.

Emily Cochrane and Tracey Tully contributed reporting.

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