US health officials on Tuesday authorized a plan to stretch the country’s limited supply of monkeypox vaccine by giving people just one-fifth the usual dose, citing research that suggests the reduced amount is nearly as effective .
The so-called dose-sparing approach also calls for giving the Jynneos vaccine with an injection just under the skin rather than into deeper tissue, a practice that can better boost the immune system. Recipients would still receive two shots four weeks apart.
The highly unusual step is a stark acknowledgment that the US currently lacks the supplies needed to vaccinate everyone seeking protection against the fast-spreading virus.
Read more: US declares monkeypox a health emergency. Should Canada do the same?
That includes 1.6 to 1.7 million Americans considered by federal officials to be at higher risk of the disease, mostly men with HIV or men who are at increased risk of contracting it. Vaccinating this group would require about three times as many full doses as the roughly 1.1 million that officials have made available.
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White House smallpox response coordinator Robert Fenton said the plan would help the United States “stay ahead of the virus.”
“It is safe, effective and will significantly increase the volume of vaccine doses available to communities across the country,” Fenton told reporters.
3:58 Dr. Fauci welcomes monkeypox emergency declaration, considers way forward6
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 determination Tuesday that allows the Food and Drug Administration to expedite its review of medical products or new uses for them, such as the dose-saving technique for Jynneos.
The FDA cleared the new approach for adults age 18 and older who are at high risk of monkeypox infection. Younger people can also get the vaccine if they are considered to be at high risk, although they should get the traditional shot, the agency said.
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The announcement represents a turnaround 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 that of the full dose. About 94 percent of people who received the smaller dose had adequate levels of virus-fighting antibodies, compared with 98 percent of those who received the full dose, according to the study funded by the National Institutes of Health. Health.
Read more: Monkeypox: US declares health emergency amid outbreak
According to the agency, the NIH plans additional testing of the technique in the coming months.
Vaccine manufacturers often formulate their shots to provide more than enough protection, so it’s not surprising that a smaller dose can still be effective.
But some experts and advocates warned that there is little data to support the policy and worry that it could backfire if it reduces the vaccine’s effectiveness.
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“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.
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5:36 White House says monkeypox public health emergency declaration will speed vaccine distribution White House says monkeypox public health emergency declaration will speed vaccine distribution vaccines
Smaller doses also require a different type of injection that penetrates only the top layer of skin, rather than the bottom layer between the skin and the muscle. This is a less common technique that may require training for some health professionals. It is also associated with more side effects such as redness, itching and swelling.
The shallower injection is thought to help stimulate the immune system because the skin contains many immune cells that target external 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 endorsed the approach to address outbreaks of yellow fever, polio and other diseases.
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“This is not an unusual 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 don’t have enough supply, do you make that commitment?”
Read more: Monkeypox: Biden promises accelerated virus response as more states declare emergencies
When the first vaccines against COVID-19 became available in late 2020, the UK government prioritized giving a first dose to as many people as possible before providing the second vaccines.
Both the UK and Canada have adopted a single-dose vaccine strategy that prioritizes people who face the highest 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 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 already been exposed to monkeypox or are likely to have it because of recent sexual contact in areas where the virus is spreading.
The Biden administration has been criticized for not quickly gathering millions more doses from the nation’s strategic national stockpile. Officials have ordered 5 million shots since July, but most are not expected to be delivered until 2023.
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The US government holds 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 places orders from other nations.
HHS responded to criticism last week about the pace and timing of the government’s vaccine decisions.
“We were thinking about how and when to use the vaccine in bulk because once you throw it out in bulk, you lose years of shelf life,” a spokesman said in an emailed statement.
The FDA approved Jynneos’ vaccine in 2019 to prevent smallpox and monkeypox based, in part, on studies in monkeys. According to FDA labeling, animals that received the two-dose vaccine were more than twice as likely to survive as those that did not after being infected with monkeypox.
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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 either monkeypox or its relative smallpox, which was eradicated decades ago.
This is typical of many of the national stockpile vaccines and drugs that treat rare or deadly pathogens such as anthrax or 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.
© 2022 The Canadian Press