US health officials on Tuesday approved a plan to stretch the nation’sof monkeypox vaccine by giving people just one-fifth of the usual dose, citing research that suggests the reduced amount is about as effective.
The so-called dose-sparing approach also requires administering the Jynneos vaccine with an injection just under the skin rather than into deeper tissue – a practice that may better strengthen the immune system. Recipients will still get two shots four weeks apart.
The highly unusual step is a stark acknowledgment that the United States currently lacks the supplies needed to vaccinate everyone seeking protection against the fast-spreading virus.
That includes 1.6 million to 1.7 million Americans who are considered by federal officials to be at the highest risk of the disease, primarily men with HIV or men at higher risk of getting it. Vaccinating that group would require about three times as many full doses as the roughly 1.1 million officials have made available.
The White House’s 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 significantly scale 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 Tuesday that allows the Food and Drug Administration to speed up its review of medical products or new uses for them, such as the dose-saving technique for Jynneos.
The FDA approved the new approach for adults 18 and older who are at high risk for monkeypox. Younger people can also get the vaccine if they are considered high risk, although they should get the traditional injection, the agency said.
The announcement represents a reversal 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 one-fifth the traditional dose generated a robust immune system response comparable to the full dose. About 94% of people who received the smaller dose had adequate levels of virus-fighting antibodies, compared with 98% of those who received the full dose, according to the study funded by the National Institutes of Health.
The NIH is planning an additional trial of the technique in the coming months, according to the agency.
Vaccine manufacturers often formulate their shots to provide more than enough protection, so it’s not unusual for a smaller dose to still prove effective.
But some experts and advocates warned that there is little data to support the policy and worried that it could backfire if it reduces the vaccine’s effectiveness.
“We have serious concerns about the limited amount of research that has been done on this dose and method of administration, and we fear that it will give people a false sense of confidence that they are protected,” said David Harvey of the National Coalition of STD Directors. , in a statement.
The smaller doses also require a different type of injection that penetrates only the top layer of skin, instead of the lower layer between skin and muscle. It is a less common technique that may require training for some healthcare professionals. It is also associated with several side effects such as redness, itching and swelling.
The shallower injection is thought to help stimulate the immune system because the skin contains many immunity cells that target outside invaders.
The Centers for Disease Control and Prevention said it will provide educational materials about the technique along with 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 supported the approach to deal with outbreaks of yellow fever, polio and other diseases.
“This is not an unusual situation,” said Dr. William Moss of Johns Hopkins’ Vaccine Access Center. “It comes down to the public health decision: In the middle of an outbreak where you have inadequate supply, do you make this trade-off?”
When the first COVID-19 vaccines became available in late 2020, the UK government prioritized giving a first dose to as many people as possible before giving other vaccinations.
Both the UK and Canada have adopted a single-dose vaccine strategy that prioritizes people at greatest risk of monkeypox. And health departments in several major US cities adopted a similar strategy amid limited supplies, including New York, San Francisco and Washington.
US officials have sent more than 617,000 full vaccine doses to state and local health departments and plan to distribute another 380,000 in the coming weeks. So far, it has been recommended for people who have already been exposed to monkeypox or who are likely to get it due to recent sexual contacts in areas where the virus is spreading.
The Biden administration has come under fire for not quickly gathering several million doses from the nation’s strategic national stockpile. Officials have ordered 5 million rounds since July, but most are not expected to be delivered until 2023.
The US government owns 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 expected to take months as the small company orders from other nations.
HHS responded to criticism last week about the pace and timing of the government’s vaccine decisions.
“We were thoughtful about how and when to use bulk vaccine because when you remove it from bulk, you lose years of shelf life,” a spokesperson said in an emailed statement.
The FDA approved the Jynneos vaccine in 2019 to prevent smallpox and monkeypox, based in part on studies in monkeys. Animals that received the two-dose vaccination were more than twice as likely to survive than those that did not after being infected with monkeypox, according to the FDA labeling.
Additional human studies showed that people who received Jynneos had an immune response similar to those who received an older smallpox vaccine. But Jynneos has not been tested in humans with either monkeypox or its relative smallpox, which was eradicated decades ago.
It is typical of many of the vaccines and drugs in the national stockpile that treat rare or deadly pathogens such as anthrax or the plague.
The US government has spent more than $1 billion developing and stockpiling 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 US to supply the new vaccine.