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Home » Monkeypox virus — what is it and is there a vaccine?

Monkeypox virus — what is it and is there a vaccine?

Massachusetts health authorities confirmed a case of monkeypox on 18 May 2022 after the CDC said it was monitoring the possible spread of the rare but potentially serious viral illness. The virus has spread in several countries and the CDC believes that the actual number of cases is being underreported because few physicians know much about the disease.

When I first heard about the novel coronavirus, I thought that the press was exaggerating and that the disease would disappear in a few weeks. Yes, I was wrong, very wrong.

When I read the first reports of a monkeypox outbreak, I decided to write about it because I was getting questions about the seriousness of the disease and if there was a vaccine for it. It is a serious disease, and as for the vaccine, it’s complicated.

So, let’s talk about monkeypox and potential vaccines.

What is monkeypox?

Monkeypox is caused by the monkeypox virus which is a double-stranded DNA, zoonotic virus. It is one of the human orthopoxviruses that includes variola (smallpox), cowpox, and vaccinia viruses. But it is not a direct ancestor to, nor a direct descendant of, the variola virus which causes smallpox. Monkeypox virus causes a disease that is similar to smallpox but with a milder rash and lower death rate.

The monkeypox virus is endemic to the tropical rainforests of West Africa and is found in primates and some other animals, such as the Gambian pouched rat.

According to the CDC, symptoms begin with fever, headache, muscle pains, swollen lymph nodes, and feeling tired. This is followed by a rash that forms blisters and crusts over. The time from exposure to onset of symptoms is around 10 days. The duration of symptoms is typically two to four weeks. The symptoms are similar to chickenpox, although the Varicella zoster virus that causes chickenpox is not related to the monkeypox virus.

The CDC states that:

Transmission of monkeypox virus occurs when a person comes into contact with the virus from an animal, human, or materials contaminated with the virus. The virus enters the body through broken skin (even if not visible), respiratory tract, or the mucous membranes (eyes, nose, or mouth). Animal-to-human transmission may occur by bite or scratch, bush meat preparation, direct contact with body fluids or lesion material, or indirect contact with lesion material, such as through contaminated bedding. Human-to-human transmission is thought to occur primarily through large respiratory droplets.

The mortality rate for the disease ranges from 1% to 10%, depending on the variant (yes, we’ll be talking about variants again).

Monkeypox can be treated with anti-viral medications such as cidofovir. There may be other anti-viral drugs that can be used, but they have not been tested against this disease as of this time. You can bet there will be a lot of published articles on new drugs for monkeypox in the next few months.

focus photography of gray monkey
Photo by prasanthdas ds on

The 2022 outbreak

The monkeypox outbreak was first detected in the United Kingdom on 29 April 2022 with the presentation of monkeypox symptoms in a British resident who had traveled to Nigeria, where the disease is endemic. The individual subsequently returned to the United Kingdom on 4 May, importing the index case of the outbreak into the country.

As of the date of this article (19 May 2022) cases of the virus have also been reported in North East England as well as outside the UK — five in Portugal, one in Sweden, one in Italy, one in the United States, seven in Canada and seven in Spain.

There was another outbreak of monkeypox in 2003 in the USA during which about 40 people contracted the disease. Most of the 2003 outbreak cases were linked to a shipment of live animals from Ghana.

Vials of medications. Dark blue.


There is good news and bad news. There is no vaccine for monkeypox itself, but there is a vaccine (for smallpox) that may be effective against the monkeypox virus. The vaccine, JYNNEOS (known as Imvamune in Canada and Imvanex in the EU) is an attenuated live virus vaccine, manufactured by Bavarian Nordic, that has been approved by the U.S. FDA for the prevention of monkeypox. The Advisory Committee on Immunization Practices (ACIP) is currently evaluating JYNNEOSTM for the protection of people at risk of occupational exposure to orthopoxviruses such as smallpox and monkeypox in a pre-event setting. I’m sure this discussion will move to near the top of the list in future ACIP meetings. The vaccine is also approved in Canada and the EU for smallpox and monkeypox.

The USA has ordered 13 million doses of the vaccine for delivery in 2023 and 2024. I’m sure that if this outbreak grows, all countries will be scrambling to order the vaccine and speed up deliveries.

Many people were vaccinated against smallpox across the world through the late 1970s before the virus was eradicated in 1978 when the last known case was identified. Since then few people have received a smallpox vaccination, usually those who study these diseases and the military who might be subject to biological warfare (as many countries have stocks of smallpox).

I could not find any information about the effectiveness of the vaccine against the monkeypox virus for those who received the smallpox vaccine 40 or more years ago. However, there may be waning immunity against smallpox (or monkeypox), but it is unknown. Without any evidence supporting what I’m about to say, I’m guessing that having the smallpox vaccine, even 40 years ago, may provide some protection against monkeypox.


I know most of you are tired of hearing about new disease outbreaks. And I’m not sure if monkeypox will become a thing in 2022, or just fade away quickly. Of course, our radar is on full sensitivity for any new disease after dealing with COVID-19 for over two years.

Monkeypox is not a trivial disease. The death rate, somewhere between 1-10% is alarming. But we don’t have information, such as infectivity rate and effectiveness of vaccines given over 40 years ago, that might allow public health institutions, like the CDC, to give us some direction. Right now, the CDC is telling us to practice good hygiene, wear personal protective equipment around those who might be infected (my mask stays on), and avoid animals that might be infected.

I’m hoping that this will be the only article I ever write about monkeypox. Given our luck over the past two years, I’m guessing it won’t be.

If you have any information that I might have missed or you know of a peer-reviewed paper that might help fill in some of the blanks, don’t hesitate to drop it in the comments.


Michael Simpson

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