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Have vaccines been developed for MPox? The short answer is yes, they have been developed. The European Union, the United States, Canada and others approved the use of the MVA-BN vaccine during the first declared global health emergency for MPox in 2022.
The long answer is a little more complicated. (Read this also | Is India at risk after WHO’s global health emergency warning on ampox? Report says…,
What are the Ampox vaccines?
Vaccines exist to prevent monkeypox infection, but currently no vaccine specifically targets the monkeypox virus. How is this possible?
The monkeypox virus belongs to a genus of viruses called Orthopoxviruses, all of which are complex DNA viruses.
Viruses in this genus include, among others, the variola virus, which causes smallpox, the cowpox virus, and the vaccinia virus.
Viruses in this genus have a great deal of genetic similarity, so vaccines developed against other viruses can also be used to protect against amphibian infection.
How do Ampox vaccines work?
Vaccines that provide protection against ampox rely on a phenomenon called cross-reactivity.
Cross-reactivity occurs when different antigens – for example different species of viruses – appear similar to our immune system.
Imagine: since the viruses of the Orthopoxviruses are structurally similar, if a person is infected with, for example, the Variola virus, the antibodies that his cells produce against that virus will also protect him from infection with the monkeypox virus.
Cross-reactivity between antibodies to orthopoxviruses allows vaccines developed to fight smallpox, for example, to also work against ampox infections.
So can I not get Mpox if I have already had the smallpox vaccine?
The answer, for now, is this: there are no guarantees.
Smallpox was declared eradicated in 1980 after a decades-long global mass vaccination effort.
After the 1980s, mass vaccination against the disease stopped, which some researchers believe left people more susceptible to other forms of orthopoxviruses, including monkeypox virus.
In fact, people born after the end of the universal smallpox vaccination program have lower levels of antibodies against the monkeypox virus.
This explains why in the previous 2022-2023 Mpox global outbreak, men aged 18-44 years were responsible for the majority of cases.
But having previously been vaccinated against smallpox does not mean that a person is completely safe from smallpox.
Previous studies have shown that the smallpox vaccine is about 85% effective in preventing infection with the monkeypox virus, but cases of monkeypox tend to be milder in people who have been vaccinated against smallpox.
What vaccines do we currently have available?
As of August 2024, there is only one vaccine approved for use against ampox in the European Union/EEA, the United Kingdom, the United States, Switzerland, and Canada.
This is the MVA-BN vaccine, also known as Modified Vaccinia Ankara-Bavarian Nordic.
This vaccine is made from a weakened type of the vaccinia virus, a virus in the Orthopoxvirus genus, to which the monkeypox virus also belongs.
The modified vaccinia Ankara vaccine was developed in Germany in the 1950s and 60s and was originally used to prevent smallpox infection.
Its current form, MVA-BN, was developed by Danish biotech company Bavarian Nordic and has been in production since 2010. It is usually given in two doses, 28 days apart.
The World Health Organization lists two other vaccines approved by different regulatory agencies for the prevention of ampox.
During the 2022 AmPox outbreak, Japan approved the smallpox vaccine LC16, and Russia licensed OrthopoxVac for vaccination against smallpox, AmPox, and other orthopoxviruses.
In the United States and Australia, a vaccine called ACAM2000, which contains live vaccinia virus, is recommended for people at risk of orthopoxvirus infection.
Is a vaccine under development?
Yes. One example of this is a new mRNA vaccine – BNT166 – that specifically targets the antigen of the monkeypox virus, which is currently under clinical evaluation.
You will be familiar with mRNA vaccines in the global vaccination effort during the COVID-19 pandemic and beyond.
At the moment, WHO does not recommend mass vaccination programmes. It recommends that only people who are at risk or who have been exposed to the virus should be considered for vaccination.
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