The shortage of monkeypox vaccine doses in the United States, which is expected to last for several months, raises urgent questions about how effectively and for how long a single dose can protect against the virus. increase.
The vaccine, called Jynneos, is licensed for two doses, but most people at risk of infection receive one dose. Now, this shortage has led federal officials to consider a rarely used approach. This is a so-called dose sparing strategy that gives shots containing only one-fifth of a single dose.
For most recipients, one injection is enough to prevent serious illness, and there is some evidence that even small doses are effective. But preliminary research suggests that people with HIV and other conditions that weaken the immune system may be less protected than those without, according to some experts.
“One dose is better than none,” says Alexandra Yonz, M.D., an infectious disease specialist at Children’s National Hospital in Washington, DC. Even with vaccination, from infection,” she added.
Two weeks after vaccination, immunocompromised people may still need to “follow public health guidance and take all other precautions to prevent exposure,” even if an antibody response is ongoing.
The findings also suggest that full vaccination should be a priority for some men. Given supply constraints, that may be difficult.
Federal authorities have ordered about 7 million doses of Gynneos, but injections have not arrived for months.So far, the Biden administration has shipped about 600,000 doses to states, he said last week. 800,000 additional doses It was allocated to states, but distribution could take weeks.
some cities facing shortages, Washington When New York, limiting the second dose to expand supply.Food and Drug Administration and CDC officials opposed the strategy, and Jynneos approved This vaccine is given in two doses 28 days apart.
What you need to know about the monkeypox virus
What is monkeypox? Monkeypox is a virus similar to smallpox, but less severe. It was discovered in 1958 after an outbreak in monkeys kept for research. The virus was primarily found in parts of Central and West Africa, but has spread to dozens of countries in recent weeks, infecting tens of thousands of people. July 23rd, The World Health Organization has declared monkeypox a global health emergency.
But because federal health officials declared a public health emergency on Thursday, FDA Commissioner Dr. He said he was considering it, instead being injected between the layers of the skin. below it.
To administer in this manner, the FDA would need to grant Jynneos Emergency Use Authorization.
Dose sparing approaches have been used when supplies of other vaccines are in short supply. However, performing an intradermal injection requires more skill than conventional vaccination.
A single injection can forestall severe symptoms in most people, and dose-sparing strategies may work as well. It is unclear whether and, if so, how long that immunity will last, federal health officials said.
“We are in a data-free zone,” said Dr. Emily Abelding, an infectious disease expert at the National Institutes of Health. Dr. oversaw testing of Covid vaccines in special populations.
An oft-cited statistic is that this vaccine is 85% effective against monkeypox. That data is not from the Jynneos trial, A small study from 1988 It looked at the incidence of monkeypox in people who were vaccinated against smallpox early in life.
No large-scale clinical trials of Jynneos as a monkeypox vaccine have ever been conducted in humans prior to approval. I was. Compare with one created with ACAM2000an early vaccine for smallpox.
In a study led by its manufacturer, Bayern Nordic, two doses of Jynneos produced antibody levels in humans similar to one injection of ACAM2000.
After the first injection of Jynneos, antibody levels initially increased for two weeks and plateaued until the second dose four weeks later.
Scientists read that if the first dose is not followed by a second dose, the protection may not be long-lasting.
“Ideally, a second dose would be given if more than that four weeks of protection were needed,” said Dr. Yonts, a staff scientist who reviewed the data for the FDA.
She added that it might make sense to delay the second dose to eight weeks. I will,” she said.
inject 1/5 of normal Using Jynneos between skin layers, as the FDA suggested Thursday, may be effective, according to limited research.
However, research is very limited. Scientists at the NIH had planned to test the dose-sparing strategy in a clinical trial set that will begin in the next few weeks. It is unclear if these plans will be shelved or accelerated.
Information about how Gineos works in HIV-infected people, especially those with severe immune impairment, was already scarce.A study conducted by Bavarian Nordic found an antibody response to vaccination tended to be Reduction: 67% of HIV-infected people 28 days after first injection Antibodies producedcompared with 84% of uninfected people.
Yonts said data from that trial were inconclusive, but reduced antibody responses are common in immunocompromised patients who receive other vaccines. while researchers found that HIV patients have a breakthrough infection.
“People with severe or moderate immunosuppression should be given a booster dose of a common vaccine,” said Keri Alsoff, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health who led the COVID-19 vaccine research. We recommend: “As immunosuppression increases, responses to vaccines decrease.”
The CDC and the New York City Department of Health said: Jinneos is safe It is effective in people living with HIV, but authorities have not addressed its effectiveness in that population.
By contrast, UK health authorities Say “For people who are HIV-positive or have other conditions or treatments that weaken their immune system, vaccines may not protect you.
vaccination package insert Also, immunocompromised people ‘may have a reduced immune response,’ he said.
Referring to immunocompromised people, Dr Chloe Okin, an infectious disease specialist at Queen Mary University of London, said, “Two doses may be very important in this population, but this is not the public opinion. It’s not really happening in the sanitary response,” he said.
But until more doses become available, state and local health departments may have little choice but to stick with reduced regimens.
“In a vaccine-deficient environment, we must do everything we can to get the benefits of the vaccine to the city as quickly as possible,” said Patrick Garahue, spokesman for the New York City Department of Health, in a statement. it won’t work.