Insight into vaccine effectiveness against monkeypox in Sept. at earliest: Virologist

Researchers will only be able to say anything about the effectiveness of the vaccine used against the monkeypox virus in September at the earliest, said virologist Marian Koopmans of Erasmus MC. The hospital is following 100 people who recently got vaccinated against the virus.

The Netherlands is currently vaccinating people who are at increased risk of getting monkeypox with the smallpox vaccine. That is a further-developed variant of the vaccine used until 1974 against “normal” smallpox, Koopmans explained. The Rotterdam study examines how many antibodies people make against monkeypox after a shot with the smallpox vaccine, among other things.

The vaccine has so far only been used on a small scale in African countries where the monkeypox virus has been circulating for some time. Therefore, there is little information about its effectiveness in preventing monkeypox. And that is a shame, said Koopmans. “Because there is only a little vaccine available, so you have to make sure you learn something from it. Gone is gone.”

In the Netherlands, people get two shots with a month between the first and second dose. The researchers want to find out whether it matters for the effectiveness of the vaccine whether people have already received an “old” smallpox vaccine or not. They also examine whether the second injection after a month really causes a stronger reaction in the body, said Koopmans.

It is not yet possible to say whether the vaccine is also effective in the longer term and whether it can, therefore, permanently protect people against a monkeypox infection, said the virologist. That requires a larger and longer-term study.

The Netherlands’ vaccination campaign focuses on several tens of thousands of people. Transgender people and men who have sex with men are eligible for the shot if they are HIV positive or take medication to prevent them from contracting HIV. They get the smallpox vaccine Imvanex.

Meanwhile, the first case of monkeypox in Curaçao was recorded by authorities on the island, the Ministry of Health announced this week. It is the first documented infection in the Caribbean portion of the Dutch Kingdom, though one person did test positive on the French side of Sint Maarten.

An initial positive test still needs to be confirmed by a second test conducted in a laboratory. The person who tested positive recently traveled abroad. They have been placed in isolation.