Powerful Zika vaccine protects mice and monkeys from the virus

A new vaccine against Zika virus gives mice and monkeys immunity in tests. The vaccine is based on the inactivated virus, and just one low dose is needed. 

“The critical difference between ours and everybody else’s is that it’s not a live virus. That makes it much safer and much easier to produce,” says Drew Weissman at the University of Pennsylvania, a member of the team that developed it.

One year after being declared an international health emergency, the Zika virus is still a threat, with the World Health Organization reporting cases in 70 countries and territories in the Americas, Africa, Asia and the Western Pacific so far. The virus can cause babies to be born with brain damage and abnormally small heads, called microcephaly.

There are dozens of vaccines in the pipeline, but all the other candidates require two immunisation shots, says Weissman. This can be harder to administer, and missing the second dose reduces the level of protection.

Weissman’s vaccine is also more potent, giving rhesus macaques immunity to Zika virus at one-twentieth of the dose needed for other vaccines.

In their tests, the team found that mice that received the vaccine were immune at two weeks and at five months following the dose. They also gave five rhesus macaques a single injection, and found that it conferred protection on four of them for at least five weeks afterwards. The fifth monkey had a small amount of the virus present, possibly because it received too high a dose.

“The vaccine works just as well in macaques as it does in mice, so that makes us think that it’s going to work just as well in people,” Weissman says. He is hoping to start clinical trials in humans within 18 months.