Why monkeypox vaccine shortage could threaten immunocompromised people

A shortage of doses of monkeypox vaccine in the United States, expected to last several months, raises urgent questions about how well and for how long a single shot can protect against the virus.

A vaccine called Jynneos is approved as a two-dose regimen, but most people at risk of infection get one dose — if they can find it. Now the shortage has prompted federal officials to consider a rarely used approach: a so-called dose-saving strategy that gives injections each containing only one-fifth of a single dose.

For most recipients, one shot should be enough to prevent serious illness, and there is some evidence that even smaller doses can be effective. But preliminary research suggests that some experts believe that people with HIV or other diseases that weaken the immune system may be less protected than people who do not have such diseases.

“One dose is better than none,” the doctor said. Alexandra Yonz is an infectious disease physician at the Children’s National Hospital in Washington, DC. But people with “HIV and other immunocompromised people should be aware that they may not have adequate protection against infection even with vaccination,” she added.

Even two weeks after vaccination, when an antibody reaction occurs, immunocompromised people may still need to “use all other precautions to prevent infection in accordance with public health guidelines,” she said.

The findings also suggest that some men should be given preference for full vaccination. Given supply constraints, this can be difficult.

Federal officials have ordered nearly seven million doses of Jynneos, but the shots won’t arrive until months later. So far, the Biden administration has sent about 600,000 doses to the states. He said that last week 800,000 additional doses distributed by state, but distribution could take weeks.

Faced with shortages, some cities, including Washington as well as New Yorklimit second doses to stretch supplies. Officials from the Food and Drug Administration and the CDC disagreed with the strategy, noting that Jynneos approved as a vaccine given in two doses 28 days apart.

But as federal health officials declared a public health emergency Thursday, Dr. Robert Kaliff, FDA commissioner, said the agency is currently considering injections containing only one-fifth of the usual dose, which are injected between the layers of the skin, not under it.

The FDA will need to grant Jynneos an Emergency Use Authorization in order to be used in this manner.

A dose-saving approach has been used when stocks of other vaccines are insufficient. But intradermal injections require more skill than more traditional immunizations.

One shot is probably enough to prevent severe symptoms in most people, and a dose-saving strategy may work just as well. But it’s unclear whether the reduced regimen is enough to prevent infection, and if so, how long that immunity might last, federal health officials said.

“We are in a data-free zone,” the doctor said. Emily Erbelding, an infectious disease expert at the National Institutes of Health who led Covid vaccine testing in special populations.

One frequently cited statistic is that the vaccine is 85 percent effective against monkeypox. This data is not from Jynneos trials, but from small study 1988 it studied the incidence of monkeypox among people who had been vaccinated against smallpox at an earlier age.

Prior to the approval of Jynneos as a monkeypox vaccine, there were no large clinical trials in humans. Instead, the FDA relied on measurements of antibody responses in small groups of people after Jynneos immunizations. compared to manufactured ACAM2000an earlier smallpox vaccine.

In studies conducted by its manufacturer, Bavarian Nordic, two doses of Jynneos produced antibody levels in humans that were about the same as after a single injection of ACAM2000.

Antibody levels after the first shot of Jynneos first increased for two weeks and then remained unchanged until the second dose four weeks later, when they soared to very high levels – higher than the levels recorded with ACAM2000.

Scientists believe this means that if the first dose is not followed by a second, the protection may be short-lived.

“Ideally, a second dose should be given if protection is desired for more than this four-week period,” the doctor said. Yonts, who reviewed data for the FDA as a staff scientist.

She added that delaying the second dose up to eight weeks might be reasonable. “But if it lasts for about six months, then I think priority will be given to those who have a more severe immunodeficiency,” she said.

Injection one fifth of the usual dose Jynneos between the layers of skin, the FDA suggested on Thursday, may be effective, according to limited research. There are many more immune cells in the skin that respond to vaccines.

But research is very limited. The NIH scientists planned to test the dose-saving strategy in clinical trials due to begin in a few weeks. It is unclear whether these plans will be delayed or accelerated.

Information about how Jynneos works for people with HIV, especially people with severe immune problems, was already scarce. In one study by Bavarian Nordic, antibody response to vaccination usually, decreased: 28 days after the first vaccination, 67 percent of those infected with HIV produced antibodiescompared to 84 percent of uninfected people.

While dr. Younts said the data from this trial is not conclusive, and immunocompromised people receiving other vaccines often have reduced antibody responses. For example, when evaluating vaccines against Covid, researchers found that patients with HIV were more likely to have breakthrough infections.

“In those with severe or moderate immunosuppression, additional doses of conventional vaccines are recommended,” said Keri Altoff, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health who led the Covid vaccine study. “If immune suppression increases, response to vaccines decreases.”

CDC and New York City Department of Health Speak Jeanneos is safe for people with HIV, but agencies have not reviewed its effectiveness for this population.

By contrast, health officials in the UK to tell that for people who are “HIV positive or have any other disease or treatment that weakens the immune system, the vaccine may not protect you.”

Vaccines package insert also notes that in immunocompromised individuals, “the immune response may be reduced.”

“Two shots can be very important for this population, which is not really happening in the public health response,” said Dr. Chloe Orkin, an infectious disease doctor at Queen Mary University of London, speaks about immunocompromised people.

But until more doses are available, state and local health departments may have little choice but to stick to reduced schedules.

“With a shortage, we must do everything we can to get the benefit of the city’s vaccine as quickly as possible,” New York City Health Department spokesman Patrick Gallahue said in a statement.