Vaccines are offered to people at higher risk of monkeypox, but doses are limited.
Why it matters
Getting vaccinated before or after exposure can reduce your risk of getting the disease and slow its spread.
What does that mean for you?
Some men who have sex with men are eligible for the vaccine, as are others who may have been exposed to monkeypox. Given the limited supply, you will probably only get the first dose of the two-dose vaccine for now.
More than 5,000 cases of monkeypox have been confirmed in the US as of July 29, and that number is expected to rise as testing increases. To slow the spread of the disease, health officials are releasing doses of a vaccine approved for monkeypox and smallpox, but reports of scheduling problems as demand outstrips supply have sparked a public health response.
In an effort to shift more resources to the outbreak, New York — the epicenter of the monkeypox outbreak — has joined New York state and San Francisco in declaring monkeypox a public health emergency. In a July 30 press release, New York City Mayor Eric Adams estimated that approximately 150,000 New Yorkers are currently at risk of contracting monkeypox. As of July 29, more than 1,200 people have tested positive for monkeypox in the city.
Jynneos, the vaccine being shipped to states and cities, is primarily intended for men who have sex with men and other people who may be exposed and are currently at higher risk of an outbreak. Federal officials have acknowledged that demand for the vaccine is outstripping supply, and the U.S. Department of Health and Human Services is sending more doses to states. As of July 28, HHS said it had shipped 340,000 doses across the US, with plans to release an additional 786,000 doses.
The federal government has pledged to make a total of 6.9 million doses available by mid-2023, but some critics warn that the public health response to monkeypox has been too slow and that by the time those doses are able to reach arms people, it may be too late to stop the spread of the disease in the US.
“We’re kind of playing catch-up,” said Dr. Amesh Adalja, an infectious disease expert and senior scientist at the Johns Hopkins Center for Health Security.
In areas with many cases, such as San Francisco, New York City, and Washington, DC, people who are eligible for the vaccine receive only the first dose of a two-dose series. Officials say this will still offer protection against monkeypox and is in line with the response in other countries, including Canada and the UK.
Here’s what we know about the Jynneos monkeypox vaccine and who’s eligible for it. Also, here’s what you need to know about ACAM2000, an older-generation vaccine that also works against monkeypox.
What is the monkeypox vaccine?
The US has two vaccines that work against monkeypox in its national stockpile. Both are expected to work before exposure to monkeypox, as well as after exposure but before symptoms begin. (The fact that vaccines work after exposure sets monkeypox apart from diseases like COVID-19.)
Jynneos (manufactured by Bavarian Nordic) is a new generation vaccine approved by the US Food and Drug Administration in 2019 for monkeypox and smallpox. It is a two-dose vaccine, and each injection is given four weeks apart. It uses a weakened virus and is approved for adults 18 and older who are at high risk of contracting monkeypox or measles.
Jynneos is a vaccine that is supplied and is currently being used to combat monkeypox in the US. Due to limited supply, you may only be able to book an appointment for the first dose for now. In New York, for example, health officials say they will contact you if you receive the first dose about a second dose in the coming weeks.
ACAM2000 is a second-generation measles vaccine that also works against monkeypox. (The two diseases are closely related and both caused by orthopoxviruses, which makes this possible.) If needed, the US Department of Health and Human Services has said it is also ready to supply the ACAM2000 vaccine, which is in greater stock than Jynneos, but remains the second choice in response to monkeypox because it has a side effect profile that is not safe for certain people.
ACAM2000 is administered differently than the typical vaccine we are used to. It is administered by dipping a needle into the vaccine solution, which will then be “stabbed” several times in the upper arm. This will cause a localized infection (“pox”), which will trigger an immune response.
Although ACAM2000 does not cause smallpox, it does contain live vaccine virus, which is not suitable for everyone. It may be unsafe for immunocompromised people, pregnant women and those with certain heart or skin conditions, such as eczema.
Smallpox was declared eliminated from the world in 1980. The US stopped routine vaccination against it in 1972, although some health care workers or people working in laboratories may have had the vaccine. According to the CDC, ACAM2000 is a derivative of Dryvax, which helped eradicate smallpox.
Vaccine requirements: Who is eligible for the monkeypox vaccine?
The exact criteria for who should get the monkeypox vaccine depends on the city or state where people live and how widespread the epidemic is, but men who have sex with men and who have had multiple or anonymous sexual partners in the past two weeks are eligible in cities like New York. That’s because most cases in the current outbreak are in gay and bisexual men, although anyone in close contact with monkeypox can get the disease.
According to the CDC, you meet the criteria for the monkeypox vaccine if you:
- You are a contact of someone with monkeypox or have been identified as possibly exposed through contact tracing.
- You have had a sexual partner in the last two weeks who has monkeypox.
- You have had multiple sexual partners in the past two weeks in an area with a high incidence of monkeypox.
- You are a laboratory or healthcare worker who works with orthopoxviruses, including animals.
If you are concerned about monkeypox and think you may be at high risk of exposure, check your city and state’s current guidelines. You can also check with your doctor or book a vaccine appointment online, a process that will walk you through the eligibility criteria. Here is the New York website for scheduling vaccines. You can make an appointment and find the vaccine in San Francisco by calling one of the city’s clinics or visiting its location.
How effective are vaccines? How long do they need to work?
If Jynneos is given within four days of exposure to monkeypox, it is the best option for stopping the disease from occurring, according to the CDC. If given four to 14 days after exposure, the CDC says Jynneos may not prevent monkeypox, but it will likely reduce the severity of your symptoms.
The CDC says that the Jynneos vaccine takes two weeks (14 days) after the second dose to build immunity, and that ACAM2000 takes four weeks for maximum immunity. Although many people only receive the first dose of Jynneos at this time, early research suggests that one dose will still provide some protection, at least for a short period of time.
Because the monkeypox outbreak in the U.S. is so new, there is still no data on how effective vaccines will be in the current situation, according to the CDC. The effectiveness of Jynneos against monkeypox is confirmed by animal studies, according to the agency. And while it won’t be used in most cases, ACAM2000 is closely related to Dryvax, the vaccine that helped get rid of measles. The effectiveness of ACAM2000 is supported by animal studies as well as human clinical trials.
You should still self-isolate if you develop monkeypox symptoms, such as a rash, after vaccination.
Why does the US stockpile monkeypox vaccines?
The US has stockpiles of Jynneos and ACAM2000 on hand not because the country was worried about an outbreak of monkeypox (which has been endemic in some African countries for years), but in case smallpox becomes a public threat again. Smallpox was declared eliminated in the 1980s, and the last natural outbreak in the U.S. occurred in 1949. But smallpox is usually much more severe than monkeypox, and officials worry it could be used as biological warfare.
“The stockpile was created in case of a biological weapons attack on the United States with smallpox,” Adalja says. In that case, health officials would not ration vaccines or use only a newer generation vaccine, says Adalja.
“If there was an attack of smallpox, we would use all the vaccines we have to deal with it,” he added.
The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health care professional with any questions you may have about your health condition or health goals.