US to expand supply of monkeypox vaccines with lower doses

WASHINGTON — U.S. health officials on Tuesday authorized a plan to expand the nation’s limited supply of the monkeypox vaccine by giving people only a fifth of the usual dose, citing research suggesting the amount reduced is about as effective.

The so-called dose-saving approach also calls for administering the Jynneos vaccine with an injection just under the skin rather than into deeper tissues – a practice that can better stimulate the immune system. Recipients would still receive two injections spaced four weeks apart.

This highly unusual step is a stark acknowledgment that the United States currently lacks the supplies needed to vaccinate all those seeking protection against the rapidly spreading virus.

This includes 1.6 million to 1.7 million Americans considered by federal authorities to be most at risk of contracting the disease, mostly HIV-positive men or men who are at higher risk of contracting it. Vaccinating this group would require about three times as many full doses as the roughly 1.1 million authorities have made available.

White House monkeypox response coordinator Robert Fenton said the plan would help the United States “stay ahead of the virus.”

“It’s safe, it’s effective, and it will dramatically increase the volume of vaccine doses available to communities across the country,” Fenton told reporters.

The Biden administration declared monkeypox a public health emergency last week in an effort to slow the growing outbreak that has infected more than 8,900 Americans. Officials announced a separate decision on Tuesday that allows the Food and Drug Administration to expedite its review of medical products or their new uses, such as the dose-saving technique for Jynneos.

The FDA has cleared the new approach for adults 18 and older who are at high risk for monkeypox infection. Young people can also get the shot if they are deemed to be at high risk, although they should receive the traditional injection, the agency said.

The announcement represents a U-turn from last month, when the FDA and other agencies repeatedly stressed that two full doses of the vaccine were needed for adequate protection.

But regulators are now pointing to a 2015 study showing that vaccination with a fifth of the traditional dose generated a robust immune system response comparable to that of the full dose. About 94% of people given the lowest dose had adequate levels of anti-virus antibodies, compared with 98% of those given the full dose, according to the study funded by the National Institutes of Health.

The NIH plans an additional trial of the technique in the coming months, according to the agency.

Vaccine manufacturers often formulate their vaccines to provide more than enough protection, so it’s not uncommon that a lower dose may still prove effective.

But some experts and advocates warned there was little data to support the policy and feared it could backfire if it reduced the effectiveness of the vaccine.

“We are very concerned about the limited amount of research that has been done on this dose and method of administration, and we fear it may give people a false sense of confidence that they are protected,” said David Harvey. of the National Coalition of STD Directors. , in a report.

Lower doses also require a different type of injection that only penetrates the top layer of skin, rather than the bottom layer between skin and muscle. It is a less common technique that may require training for some medical professionals. It is also associated with more side effects such as redness, itching and swelling.

The shallower injection is thought to help boost the immune system because the skin contains many immune cells that target outside invaders.

The Centers for Disease Control and Prevention said they would provide educational materials on the technique as well as a broader awareness campaign for US health departments.

Rationing of vaccine doses is common in Africa and other parts of the world with limited health resources. In recent years, the World Health Organization has endorsed the approach to control outbreaks of yellow fever, poliomyelitis and other diseases.

“It’s not an uncommon situation,” said Dr. William Moss of the Johns Hopkins Vaccine Access Center. “It comes down to public health decision-making: in the middle of an outbreak where you have insufficient supply, do you make that trade-off?”

When the first COVID-19 vaccines became available in late 2020, the UK government prioritized getting a first dose to as many people as possible before providing a second vaccination.

Both the UK and Canada have adopted a single-dose vaccination strategy prioritizing those most at risk of monkeypox. And health departments in several major US cities have adopted a similar strategy amid tight supplies, including New York, San Francisco and Washington.

US officials have shipped more than 617,000 full doses of vaccines to state and local health departments and plan to distribute 380,000 more in the coming weeks. So far, it has been recommended for people who have either been exposed to monkeypox in the past or are at risk of catching it from recent sexual contact in areas where the virus is spreading.

The Biden administration has been criticized for not quickly gathering millions of additional doses from the country’s strategic national stockpile. Authorities have ordered 5 million snaps since July, but most are not expected to be delivered until 2023.

The US government has bulk vaccine ingredients equivalent to 16.1 million doses under contracts with Danish manufacturer Bavarian Nordic. But the material must be sealed in vials, a process that is expected to take months as the small company fills orders from other countries.

HHS responded to criticism last week about the pace and timing of government vaccine decisions.

“We thought about how and when to use the vaccine in bulk, because once you remove it from the bulk, you lose years of shelf life,” a spokesperson said in a mailed statement. electronic.

The FDA approved the Jynneos vaccine in 2019 to prevent smallpox and monkeypox based, in part, on monkey studies. According to FDA labeling, animals that received the two-dose vaccination were more than twice as likely to survive as those that did not after being infected with monkeypox.

Additional human studies showed that people who received Jynneos had a similar immune response to those who received an older smallpox vaccine. But Jynneos has not been tested in humans with monkeypox or its relative, which was eradicated decades ago.

This is typical of many national stockpile vaccines and drugs that treat rare or deadly pathogens like anthrax or the plague.

The US government spent more than $1 billion to develop and store the freeze-dried vaccine, which replaced an earlier liquid version that had a shorter shelf life. Bavarian Nordic has a 10-year contract with the United States to supply the new vaccine.


The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute Department of Science Education. The AP is solely responsible for all content.

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