(The conversation) – Monkeypox will not be the next COVID-19. But with the epidemic having blossomed in thousands of infections, with cases in nearly every state, on August 4, 2022, the The United States has declared monkeypox a national public health emergency.. One of the reasons health experts did not expect monkeypox to become so widespread is that the United States had previously approved two vaccines against the virus. Maureen Ferranvirologist at the Rochester Institute of Technology, has been keeping tabs on two vaccines that can protect against monkeypox.
1. What vaccines are available against monkeypox?
Two vaccines are currently approved in the United States that may provide protection against monkeypox, Jynnéos vaccine – known as Imvamune/Imvanex in Europe – and ACAM2000an old smallpox vaccine.
The Jynneos vaccine is produced by Bavarian Nordic, a small business in Denmark. The vaccine is intended for the prevention of smallpox and monkeypox in adults aged 18 years and over who are at high risk of infection with either virus. It was approved in Europe in 2013 and by the United States Food and Drug Administration in 2019.
The Jynneos vaccine is given in two doses four weeks apart and contains live vaccinia virus. Vaccinia normally infects cattle and is a type of poxvirus, a family of viruses that includes smallpox and monkeypox. The virus in this vaccine has been crippled – or attenuated – so that it can no longer replicate in cells.
This vaccine is effective in protecting people at high risk for monkeypox from infection before exposure and may also reduce the severity of illness after infection. It is effective against smallpox as well as monkeypox. Until the recent outbreak of monkeypox, this vaccine was primarily given to healthcare workers or people with confirmed or suspected exposure to monkeypox.
The ACAM2000 vaccine has been FDA approved in 2007 for protection against smallpox. This vaccine is also based on vaccinia virus, but the version of vaccinia virus in the ACAM2000 vaccine is able to replicate in a person’s cells. Therefore, the ACAM2000 vaccine can be associated with serious side effects. These can include serious skin infections as well as life-threatening heart problems in vulnerable people. Another potential problem with the ACAM2000 vaccine is that it is more complicated to administer compared to a normal injection.
The US government has more 200 million doses of ACAM2000 stored in the event of a smallpox bioweapon attack. But despite the adequate supply of vaccine, ACAM2000 is not used to vaccinate against monkeypox due to the risk of serious adverse side effects. At this time, only designated U.S. military personnel and laboratory researchers who work with certain poxviruses can receive this vaccine.
2. How effective are these vaccines?
According to the United States Centers for Disease Control, there are no data yet available on the effectiveness of either vaccine in the current monkeypox epidemic. But there is older data from animal studies, clinical trials and studies in Africa.
A number of clinical trials conducted during the Jynneos vaccine approval process show that when given to a person, it triggers a strong antibody response on par with the ACAM2000 vaccine. An additional study in non-human primates showed that vaccinated animals infected with monkeypox survived 80% to 100% of the time, versus 0 to 40% survival in unvaccinated animals.
Another use of the Jynneos vaccine is as post-exposure prophylaxis or PEP, which means that the vaccine can be effective even when given after exposure to the virus. Since the monkeypox virus incubates in a person’s body for six to 14 days, the body of a person who receives the Jynneos vaccine shortly after being exposed will produce antibodies that can help fight infection and protect against a severe case of monkeypox.
ACAM2000 data is older and less accurate but shows strong protection. The researchers tested the vaccine during an epidemic of monkeypox in central Africa in the 1980s. Although the study was small and did not directly test the effectiveness of the vaccine, the authors concluded that the unvaccinated people faced a 85% more likely to be infected than vaccinated people.
3. Does a smallpox vaccine protect against monkeypox?
According to the CDCprevious smallpox vaccination provides some protection against monkeypox, although this protection decreases over time. Experts advise anyone with the smallpox vaccine more than three years ago and is at increased risk of monkeypox receiving the monkeypox vaccine.
4. Who should get vaccinated?
At the national level, anyone who has been in close contact with an infected person, who has a weakened immune system or who has had dermatitis or eczema is eligible for a Jynneos vaccine.
Some state and local governments also make vaccines available to people in communities most at risk for monkeypox. For example, New York City allows men who have sex with men who have had multiple sex partners in the last 14 days to get vaccinated.
5. What does the Jynneos vaccine supply look like?
As of July 29, 2022, a little more 300,000 doses were delivered to points of care or administered, with another 700,000 already allocated to US states. However, the demand far exceeds the supply. Public health officials recognize that vaccine supply shortages have resulted in long queues and clinics must close when they run out of vaccines. The problems were amplified by technical problems with online booking systemsespecially in New York.
To help boost supply, the United States has ordered nearly 7 million doses of the Jynneos vaccine, which are expected to arrive over the next few months.
6. What if you only use one dose of Jynneos?
Although federal health officials advise against withholding the second dose, some locations, including washington dc, and New York City – withhold second dose until more are available. This strategy is also used in Britain and Canada to vaccinate as many people as possible at least once.
A previous study reported that a single shot Jynneos vaccine protected monkeys infected with monkeypox and that this protection lasted at least two years. If this holds true in the real world, it would support suspending second doses in favor of vaccinating more Americans. This would be essential as many health experts expect the virus to continue to spread, increasing the growing demand for vaccines.