The European Medicines Agency’s (EMA) human medicines committee (CHMP) has suggested that the smallpox vaccine Imvanex’s indication be expanded to include protection against monkeypox disease in adults.

Since 2013, the drug has been licenced in the EU for the prevention of smallpox. It contains a weakened variant of the vaccinia virus known as ‘modified vaccinia virus Ankara,’ which is related to the smallpox virus.

Also read: WHO declares monkeypox a global emergency. What does it mean?

Because of the similarities between the monkeypox virus and the smallpox virus, it was also considered a potential vaccination for monkeypox. Bavarian Nordic A/S holds the marketing rights to the vaccine.

How is it used?

Imvanex is administered through subcutaneous injection, or just under the skin, preferably in the upper arm. People who have never been immunised against smallpox should receive two 0.5 ml doses, the second at least 28 days following the first.

If a booster dose is required for those who have previously been immunised against smallpox, a single 0.5 ml dose should be administered, with the exception of patients with a weakened immune system (the body’s natural defences), who should receive two booster doses, with the second dose administered at least 28 days after the first.

Also read: What is monkeypox? All you need to know

The vaccine is only available with a prescription.

How does it work?

Vaccines function by ‘teaching’ the immune system how to fight disease. When a person receives the vaccination, his or her immune system recognises the virus in the vaccine as ‘foreign,’ and antibodies are produced against it. When the person comes into touch with this or a similar virus again, the antibodies, together with other immune system components, will be able to kill the viruses and help defend against the disease.

Imvanex contains vaccinia Ankara, a modified variant of the vaccinia virus that does not cause disease in humans and cannot duplicate (reproduce) in human cells. Because this virus is related to the smallpox virus, antibodies developed against it are predicted to protect against smallpox. Vaccines containing vaccinia viruses proved effective in the smallpox eradication campaign.

Also read: Monkeypox outbreak: 5 things to know about the disease

Side effects

The most common Imvanex side effects (which may affect more than one out of every ten persons) include headache, nausea, myalgia (muscle pain), weariness, and injection site responses (pain, redness, swelling, hardening and itching).

Imvanex should not be used in patients who are hypersensitive (allergic) to the active ingredient or any of the trace ingredients, such as chicken protein, benzonase, or gentamicin.