Officials are debating whether to authorize a new vaccination strategy against monkey pox

WASHINGTON – It sounded like a simple solution to the monkey pox vaccine shortage: just by changing the way the doses are injected, the federal government could vaccinate five times as many people with the resources available.

Experts say the approach – injecting a fifth of the current dose into the skin instead of the full dose into adipose tissue – isn’t all that simple. Some federal officials are concerned about the method change without further testing, even though Dr. Robert M. Califf, head of the Food and Drug Administration, described the proposal as promising on Thursday.

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

Stretching the doses of the Jynneos vaccine could help the federal government solve the problem, partly by itself. Even though it has invested over $ 1 billion in developing a two-dose vaccine for use against both monkey pox and smallpox, the government has only 1.1 million injections on hand, partly because of the slow ordering of massive stocks of vaccines to be processed into vials.

This supply is sufficient 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, according to the Centers for Disease Control and Prevention, are at high risk of monkey pox. For now, the virus is mostly spread through skin contact during sex among gay and bisexual men, the CDC said.

Some federal officials hope that by injecting a lower dose of the vaccine between the layers of the skin, called an intradermal injection, the Biden administration could contain the epidemic before it spreads more widely.

However, some experts say this approach has not been sufficiently researched. They also warn that some vaccinators will need training to get vaccinated properly, which could slow down vaccination efforts. Otherwise, the government might be wasting doses rather than saving them.

Intradermal injection consists in carefully inserting a needle into the layers of the skin, a thin space with immune cells. Experts say that if the vaccinator goes too deep and puts the dose into the fat, the patient may not get enough of the vaccine. But if the needle is not inserted far enough, some of the vaccine may leak back.

“If you are giving a lower dose and not injecting it properly into the skin – you can inject it in the wrong place – you may not give a protective vaccine,” said Dr. Phil Krause, who retired as FDA’s senior vaccine regulator last year and worked on licensing Jynneos by agencies. “If you ask to do it all over the country in millions of doses, it’s much easier to make mistakes in administering the vaccine.”

On the other hand, this method has a proven track record. It has been used in polio vaccination campaigns when doses have been limited and in skin testing for rabies and tuberculosis.

“This is not a completely new concept,” said Dr. Anthony S. Fauci, President Biden’s chief medical advisor. “We thought of it as a vaccine shortage strategy many years ago.”

In smallpox vaccination campaigns, vaccinators used special, forked needles, which allowed them to make intradermal injections more evenly and cheaper.

Dr. John Beigel, deputy director of clinical trials at the National Institutes of Health, said the government-sponsored Jynneos study published in 2015 compared the intradermal approach with the standard injection method and found it triggered comparable levels 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 to keep the vaccine than giving just one injection, as some jurisdictions are doing today, as studies have shown that one injection does not elicit such a strong immune response.

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

Although the 2015 study had hundreds of participants, some experts note that this was a single study that was limited in what it measured. The NIH researchers planned to test the intradermal strategy for Jynneos in a trial that was due to begin in a few weeks. But the results weren’t expected until late fall or early winter, and this plan is in the air for now.

Dr. H. Clifford Lane, clinical director of Dr. Fauci’s National Institute of Allergy and Infectious Diseases at the NIH, said that while scientists can gain insight into people who have been vaccinated, a traditional clinical trial would provide a clearer picture.

“I can understand doing this as long as it is very clear why you are doing it,” he said of the intradermal strategy. “The question is, how can we stretch current stocks without significantly compromising performance?”

The next question is how well the vaccine will actually work. It was approved in 2019 for use against both monkey pox and smallpox, after studies showed that it elicited a stronger immune response than the earlier vaccine. The drug itself was approved because it was beneficial over an even earlier vaccine, federal officials said.

Monkey pox is rarely fatal and no deaths have been reported in the United States. Symptoms usually disappear within two to four weeks. But with the outbreak that has risen from eight reported cases in late May to 7,510 now, the administration is trying to improve vaccination rates and the availability of testing and treatments.

At the moment, the epidemic is almost entirely confined to men who have sex with men, and those who have multiple partners are considered particularly at risk. But so far, five cases involving children have been reported. On Friday, the Illinois Department of Public Health announced that an adult working in a kindergarten had tested positive for monkey pox and that children and other staff members were being tested there.

The announcement on Thursday of a public health emergency allowed the federal government to speed up the monkey pox investigation and approve subsidies, but did not invoke the FDA’s emergency powers. Changing the injection mode would require a second type of fallback, giving the Food and Drug Administration more flexibility to authorize emergency use.

Federal regulators can issue emergency product approvals if they believe that the potential benefits outweigh the potential risks. At the start of the coronavirus pandemic, the Trump administration issued the same type of contingency declaration, allowing the FDA to release Covid-19 vaccines to Americans months before full regulatory approval was granted.

FDA commissioner Dr Califf said on Thursday that regulators would continue to ensure that the vaccine would be delivered in a safe and effective manner. He said regulators would likely decide in the next few days whether to apply the intradermal strategy, but that “it looks good now” – a comment that some outside experts said seemed to precede the considerations of career regulators.

Emily Cochrane and Tracy Tully contributed to reporting.

Leave a Comment