we have vaccines and drugs to treat it

Medicines are not normally needed to treat monkeypox. The illness is usually mild and most infected people recover within weeks without needing treatment. But there are vaccines that can be used to control monkeypox outbreaks, which some countries are already using. And treatments exist for those who become seriously ill from the virus.

Monkeypox belongs to the Orthopoxvirus kind of virus, which includes smallpox. Fortunately, due to what is called cross-protection, smallpox vaccines also work for monkeypox.

Although the world was declared smallpox-free in 1980, many countries maintain stocks of smallpox vaccine for emergencies. For example, the smallpox vaccine is used to protect laboratory workers who accidentally come into contact with smallpox viruses (such as monkeypox or vaccinia – a smallpox virus similar to smallpox but less harmful). They are also kept in case of a terrorist attack which could use smallpox as a biological weapon.

The smallpox vaccine can be up to 85% effective in stopping infection with the monkeypox virus if given before people are exposed to the virus.

There are two types of smallpox vaccine. Both types are based on the vaccinia virus. An older type of smallpox vaccine contains “live” vaccinia virus. The main one in this group is ACAM2000, which is approved in the United States to protect people against smallpox.

Although ACAM2000 cannot cause smallpox, the vaccinia virus it contains can replicate after vaccine administration, spreading from the vaccinated person to an unvaccinated person who comes into close contact with the site. injection or any fluid leakage up to 21 days later.

This also means that ACAM2000 can cause many side effects and should not be given to groups at risk, such as pregnant or breastfeeding women, and those with weakened immune systems. People with weakened immune systems, including those with HIV, can become seriously ill from the vaccine.

Smallpox virus.
The smallpox virus belongs to the same genus as monkeypox.
phanie / Alamy Stock Photo

The other “live” vaccinia virus is Aventis Pasteur’s smallpox vaccine. It is not officially endorsed, but may be made available if other supplies run out.

A new type of smallpox vaccine, called Imvanex, contains a live but modified form of the vaccinia virus called vaccinia Ankara. Imvanex, made by Danish biotechnology company Bavarian Nordic, has been authorized in the European Union for the prevention of smallpox.

In the United States, the vaccine bears the brand name Jynneos and is licensed to prevent both smallpox and monkeypox in adults at risk for these diseases. Jynneos has been used in the UK in previous cases of monkeypox.

Since the Nordic Bavarian vaccines consist of a modified form of the vaccinia virus, they are considered safe for people in risk groups.

It would usually take between five and 21 days for someone who comes in close contact with an infected person to show symptoms of monkeypox (and most likely seven to 14 days), so it’s hard to say whether giving the vaccine after that someone has been exposed to monkeypox will fully protect them. However, the recommendation in the US and UK is that after a risk assessment, people exposed to monkeypox virus be offered a dose of modified vaccinia Ankara vaccine as soon as possible, ideally within four days, but up to 14 days later.

Antivirals

Besides vaccines, certain drugs could be used to treat monkeypox.

One such drug is tecovirimat which stops the spread of infection by interfering with a protein on the surface of Orthopoxvirus.

Tecovimat is approved in the United States for the treatment of smallpox only. It has been tested on healthy humans and has been shown to stop the smallpox virus in the laboratory. However, it has not been tested in people with smallpox or other Orthopoxvirus. However, in Europe, tecovitimat has been authorized for the treatment of smallpox, monkeypox and cowpox in exceptional circumstances.

Another antiviral that could be used is cidofovir – an injectable medicine licensed in the UK to treat serious viral eye infection in people with AIDS.

In the body, cidofovir is converted to cidofovir diphosphate, an antiviral ingredient. Since cidofovir stops smallpox in the laboratory, it could be authorized for emergency use during outbreaks of smallpox or monkeypox.

However, cidofovir is quite a strong drug and can damage the kidneys. A better alternative might therefore be brincidofovir, a closely related drug, which has been approved in the United States for the treatment of smallpox.

Brincidofovir (brand name Tembexa) is taken by mouth and can be prescribed to people of any age. Its special design helps get the right amount of drug into the cells to release the cidofovir component and also makes it less harmful to the kidneys.

Brincidofovir has been tested in humans for other viral conditions. Its approval for use in smallpox in the United States comes from laboratory studies showing it works against Orthopoxvirus. For this reason, brincidofovir is also listed as a potential drug for the treatment of monkeypox.

However, what we are still missing are data on the efficacy of cidofovir, brincidofovir and tecovitimat in the treatment of monkeypox infections in humans. A recent article, published in The Lancet Infectious Diseases, investigated the effectiveness of brincidofovir (three patients) and tecovirimat (one patient) in cases of monkeypox between 2018 and 2021 in the UK. The researchers reported low efficacy of brincidofovir and called for more studies of tecovirimat in human monkeypox infection.

Leave a Comment