Three vaccines prevent Zika infection in monkeys as trial in humans gets underway

One day after US health officials announced an early start to a clinical trial to test a Zika vaccine in humans, researchers reported in the journal Science that three different types of vaccines designed to block the virus all worked to perfection in monkeys.

The three experimental vaccines had already proven effective in mice, and their success on rhesus monkeys is “raising optimism for the development of a (Zika) vaccine for humans,” the study authors wrote.

With more than 50 countries and territories battling active Zika outbreaks, the need for a vaccine is clear. Hundreds of thousands of people have been infected, including more than 6,400 people in the US and its territories.

Although most infections cause only mild symptoms at best — including fever, rash, headache and joint or muscle pain — women who contract the virus while pregnant put their unborn children at risk of microcephaly. Affected infants are born with small heads and often experience neurological problems and cognitive deficits as they get older.

There is also some evidence that, in rare cases, a Zika infection can lead to a neurological disorder called Guillan-Barre syndrome. The Centres for Disease Control and Prevention is researching the link between the two.

“A safe and effective vaccine to prevent Zika virus infection and the devastating birth defects it causes is a public health imperative,” Dr Anthony S. Fauci, director of the National Institute for Allergy and Infectious Diseases, said in a statement.