New study shows smallpox vaccine ineffective against monkeypox

Despite previous hopes, the Department of Medical Sciences warned that most adults and seniors who have been previously vaccinated against smallpox are not protected from monkeypox, unfortunately. The news comes after testing in labs of people who received the smallpox vaccine when they were younger and are now over 40 showed no correlation between the inoculation and any immunity from monkeypox.

The smallpox vaccine has been recommended as a tool to fight the spread of monkeypox, at least until a proper vaccine created specifically for the new outbreak has been created. In fact, Thailand ordered 1,000 Jynneos smallpox vaccines, enough to administer two doses each to 500 people just in case, though who the Department of Disease Control will decide who receives them is still unconfirmed.

The chief of the Department of Medical Sciences says those first doses should go to health workers as a preventative measure, considering they are the most likely to be exposed during an outbreak and are therefore the highest risk. But, he warned, the smallpox vaccine does come with some neurological and cardiological side effects that can be fairly significant.

Scientists suspected that the smallpox vaccine could be at least somewhat effective against monkeypox because the two diseases have some striking similarities. The study tested this theory by gathering 30 people from 45 to 74 years old who had the smallpox vaccine already and used a Plaque Reduction Neutralization Test on serum from the volunteers. The tests found, according to the chief of the DMS, that any protection against the monkeypox virus is minimal at best.

“We have found that 28 of trialists had no immunity against monkeypox, although one had maintained immunity level against the disease’s A.2 variant and another against both B.1 and A.2 variants. However, overall results led to the conclusion that the majority of older Thai citizens have no marked immunity against monkeypox.”

Before anyone panics though, the department chief reminds us that there are currently no plans for mass vaccinations as monkeypox is not nearly as common or rapidly spreading as Covid-19, and personal safety measures can be protection enough for now. The National Vaccine Institute and others are working on replacing the old smallpox vaccine with an activated vaccine, and say a traditional inactivated vaccine will do for now, but there isn’t a rush to push something out quickly since monkeypox is not nearly as widespread and transmissible.

In fact, since the World Health Organisation first declared monkeypox a Public Health Emergency of International Concern on July 23, there have only been 15 deaths despite the disease spreading to over 100 countries and infecting 50,327 people worldwide.

SOURCE: Bangkok Post