US to expand supply of monkeypox vaccines with lower doses


FILE – A man holds a sign calling for increased access to the monkeypox vaccine during a protest in San Francisco, July 18, 2022. U.S. health officials on Tuesday, August 9, 2022 cleared a new vaccine strategy for monkeypox monkeypox designed to stretch limited supplies by allowing medical professionals to vaccinate up to five people – instead of one – with each vial. (AP Photo/Haven Daley, File)


US health officials on Tuesday authorized a plan to expand the country’s limited supply of the monkeypox vaccine by giving people only a fifth of the usual dose, citing research suggesting the reduced amount 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. Vaccination of this group would require more than 3.2 million vaccines.

White House officials said the new policy would immediately multiply the 440,000 full doses currently available into more than 2 million smaller doses.

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

The Biden administration declared monkeypox a public health emergency last week in an effort to slow the 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 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.

FDA officials stressed that the second dose is essential to provide protection.

“We believe quite strongly that both doses are necessary because, in part, we have no evidence that three, six, eight months later people will be adequately protected by just one dose,” said Dr Peter Marks. , from the FDA. head of vaccines.

Regulators pointed to a 2015 study showing that inoculation with one-fifth of the traditional two-dose vaccine 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 is planning further trial of the technique. And Centers for Disease Control and Prevention director Dr. Rochelle Walensky said her agency is already beginning to track real-world vaccine effectiveness in U.S. communities, though initial estimates will take time to generate.

But some experts and advocates feared that with little data to back up the policy, 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 additional training for some healthcare professionals. But infectious disease specialists said that shouldn’t be a major hurdle.

“Intradermal delivery is certainly something that has been used for other vaccines, including the smallpox vaccine, which was given to hundreds of millions of people during the 20th century,” said Anne Rimoin, director of the Center for Global and Immigrant Health at UCLA.

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

The CDC said it will 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 approved the strategy to control epidemics 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?”

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.

Officials said Tuesday that anyone who has already received a full first dose can get the smaller amount for their second dose.

US officials have shipped more than 625,000 full doses of the vaccine to state and local health departments. So far, injections have 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 strategic national stockpile. Authorities have ordered 5 million doses since July, but most are not expected to be delivered until 2023. Under the new dosing strategy, that would amount to 25 million doses.

The United States 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.

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.


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.

Lynn A. Saleh