WASHINGTON — It looked like a simple solution to the monkeypox vaccine shortage: Simply by changing how doses are injected, the federal government could vaccinate five times as many people with the supply it has on hand. .
But the approach – injecting a fifth of the current dose into the skin instead of a full dose into the underlying fat – is not so simple, experts say. And some federal officials are worried about changing the method without more research, even though Dr. Robert M. Califf, the head of the Food and Drug Administration, on Thursday called the proposal promising.
Some outside experts also urge caution. “From a basic science perspective, it should work,” said Dr. Jay K. Varma, director of the Cornell Center for Pandemic Prevention and Response. “But, of course, there are a lot of things in life, in science, that we think should work, and when we actually do them, they don’t work.”
Expanding doses of the vaccine, Jynneos, could help the federal government resolve a predicament partly of its own making. Despite investing more than $1 billion in developing the two-dose vaccine to be used against both monkeypox and smallpox, the government only has 1.1 million vaccines on hand. , in part because he was slow to order bulk vaccine stocks to make into vials.
This supply is enough to cover 550,000 people, but about three times as many doses are needed to cover the 1.6 million to 1.7 million Americans who the Centers for Disease Control and Prevention say are at high risk of monkeypox. For now, 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 the layers of the skin, called an intradermal injection, the Biden administration could stem 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 training to administer vaccines correctly, which could slow vaccination efforts. Otherwise, the government could end up wasting doses, not saving them.
Intradermal injection involves carefully guiding a needle through the layers of the skin, a thin space with immune cells. If a vaccinator goes too far and inserts the dose into the fat, the patient might not get enough vaccine, experts say. But if the needle is not inserted far enough, some of the vaccine could flow back.
“If you give a lower dose and you don’t inject it into the skin correctly – you could inject it in the wrong place – you may not be giving a protective vaccine,” said Dr Phil Krause, who retired as senior FDA vaccine regulator last year and worked on the agency’s license for Jynneos. “If you’re asking for it to be done nationwide in millions of doses, it’s much easier for there to be mistakes made in administering the vaccine.”
On the other hand, the method has proven itself. It has been used in polio vaccination campaigns when doses were limited, as well as for rabies and for tuberculosis skin testing.
What to know about the Monkeypox virus
What is monkey pox? Monkeypox is a virus similar to smallpox, but the symptoms are less severe. It was discovered in 1958, after outbreaks occurred in monkeys kept for research. The virus has mainly been found in parts of West and Central Africa, but in recent weeks it has spread to dozens of countries and infected tens of thousands of people, overwhelmingly men with sex with men. On July 23, the World Health Organization declared monkeypox a global health emergency.
“It’s not a brand new concept,” said Dr. Anthony S. Fauci, President Biden’s chief medical adviser. “We thought of it as a strategy in the event of a shortage of vaccines years ago.”
Vaccinators used special bifurcated needles in smallpox inoculation campaigns that allowed them to perform intradermal injections more uniformly and at lower cost.
Dr. John Beigel, associate director of clinical research at the National Institutes of Health, said a government-sponsored study by Jynneos published in 2015 compared the intradermal approach to the standard injection method and found that it triggered a comparable level of neutralizing antibodies, 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.
Dr Beigel said switching to the intradermal method was a better option for preserving the vaccine than giving a single injection, as some jurisdictions currently do, because research has shown that one injection does not cause a strong immune response.
“One dose is probably not effective,” he said, adding that the intradermal method “is an acceptable route.”
Although the 2015 trial involved hundreds of participants, some experts note that it was a single study limited in what it measured. The NIH researchers had planned to test Jynneos’ intradermal strategy in a trial that was due to begin in a few weeks. But results weren’t expected until late fall or early winter, and that plan is on hold for now.
Dr. H. Clifford Lane, clinical director of Dr. Fauci’s National Institute of Allergy and Infectious Diseases at the NIH, said that if researchers could glean information by tracking people who get vaccinated, a traditional clinical trial would provide a clearer picture.
“I can understand doing it as long as it’s very clear why it’s being done,” he said of the intradermal strategy. “The question is: how can we stretch current supplies without significantly compromising efficiency?”
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. That drug itself was approved because it compared favorably to an even older vaccine, federal officials said.
Monkeypox is rarely fatal and no deaths have been reported in the United States. Symptoms usually disappear in two to four weeks. But with the outbreak rising from eight cases reported in late May to 7,510 now, the administration is scrambling to try to improve vaccination rates and the availability of tests and treatments.
At present, the epidemic is almost entirely confined to men who have sex with men, with those who have multiple partners 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 daycare center tested positive for monkeypox and children and other staff there were being tested.
Thursday’s declaration of a public health emergency allowed the federal government to expedite monkeypox investigations and approve grants, but did not invoke the FDA’s emergency powers. Changing the mode of injection would require a second type of emergency declaration, giving the Food and Drug Administration more leeway to issue emergency use authorizations.
Federal regulators can issue emergency product authorizations when they believe the potential benefits outweigh the potential risks. At the start of the coronavirus pandemic, the Trump administration issued the same kind of emergency declaration, allowing the FDA to make Covid-19 vaccines available to Americans months before regulators issued full approvals. .
Dr. Califf, the FDA commissioner, said Thursday that regulators would continue to ensure the vaccine is delivered safely and effectively. He said regulators would likely decide in the next few days whether or not to go with the intradermal strategy, but it “looked good right now” – a comment that some outside experts said seemed to preempt deliberations. career regulators.
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Emily Cochrane and Tracey Tully contributed reporting.