As monkeypox cases continue to increase among high-risk people, federal officials on Tuesday announced they will stretch limited vaccine supplies by giving just one-fifth the current dosage.
The move would quintuple the existing supply of monkeypox vaccine doses, a priority in hard-hit places such as Los Angeles County and San Francisco, where the virus has been rapidly increasing in communities where men have sex with men and vaccines remain in short supply.
The U.S. Food and Drug Administration issued an emergency-use authorization allowing health care providers to use the new vaccination technique for high-risk adults.
“In recent weeks, the monkeypox virus has continued to spread at a rate that has made it clear our current vaccine supply will not meet the current demand,” FDA Commissioner Dr. Robert Califf said in a statement. “The FDA quickly explored other scientifically appropriate options to facilitate access to the vaccine for all impacted individuals. By increasing the number of available doses, more individuals who want to be vaccinated against monkeypox will now have the opportunity to do so.”
As the number of reported monkeypox cases has continued to climb, officials have been racing to get as many vaccine shots administered as possible as well as stretch the limited supply of doses.
California Gov. Gavin Newsom declared a state of emergency over the spread of the virus earlier this month to “bolster the state’s vaccination efforts.” And the White House has declared the disease a public health emergency.
Health experts say one of the only ways to get a handle on the growing outbreak is to dramatically increase vaccinations, adding that the more cases climb, the harder the spread will be to contain. Doctors fear an increased spread could result in the virus becoming endemic in the wild animal population, meaning it would be virtually impossible to remove as a new disease of concern in the U.S.
In an interview earlier this week, University of California, San Francisco infectious disease expert Dr. Peter Chin-Hong said expanding the availability of the monkeypox vaccine would be critical in responding to the outbreak. Currently, the vaccine is administered subcutaneously, or under the skin. The newer technique would administer a shot intradermally, or injecting it in a way that’s more shallow.
The expectation was that federal officials wouldn’t act until more data was available later this year on the effectiveness of the shallower injection method. But some scientists noted the intradermal technique has been used in other vaccines, such as for yellow fever, when doses are in short supply, according to Chin-Hong.
The FDA based its decision on data from a clinical study from 2015 that found that individuals who received the vaccine intradermally — between layers of the skin — got a similar immune response to those who got the shot beneath the skin.
“Administration by the intradermal route resulted in more redness, firmness, itchiness and swelling at the injection site, but less pain, and these side effects were manageable,” the FDA said in a statement.
The FDA’s action Tuesday also allows people younger than 18 at high risk of infection to get the monkeypox vaccine. But they will need a full dose administered subcutaneously, rather than the smaller intradermal dose.
In a town hall meeting with colleagues last week, Chin-Hong expressed concerns about the rate that monkeypox is spreading.
“When you look at the rates of increase, you can see that it’s really approaching an exponential curve. And unfortunately, it’s going to become harder and harder to control the ... higher these numbers get,” he said.
Anyone can get monkeypox. However, it has spread rapidly in LGBTQ communities in part because contagious lesions can appear first in the rectum, urethra and mouth before appearing on the skin, and because the first symptoms can appear as innocuous as a pimple. That makes it possible to pass on the virus to other people during intimate sexual encounters without infected people knowing that they are contagious.
Cases are rising steeply among men who have sex with men and transgender people who have sex with men, Chin-Hong said. About 98% to 99% of cases are among people in these groups.
The spread of monkeypox cases has also been amplified by Pride events, specifically in gay saunas and at pool parties where there is intimate skin-to-skin contact, Chin-Hong said. The virus is not transmitted through pool water and generally not transmitted through surfaces. It can, however, be transmitted through infected bedsheets.
The Jynneos vaccine is a two-dose series with the shots administered four weeks apart. It also can be used preventatively and within two weeks of an exposure.
However, supplies are constrained, prompting health officials to recommend prioritizing first doses rather than stockpiling second-shot supplies in many cases.
Immunocompromised individuals should receive their second dose within the 28-day interval whenever possible, officials say.
“There are no data available to indicate that one dose of Jynneos will provide long-lasting protection, which will be needed to control the current monkeypox outbreak,” the FDA said in a statement.
