Three experimental vaccines being developed by researchers at Harvard’s Beth Israel Hospital and the Walter Reed Army Institute of Research had already shown promise in mice — but monkeys are a much better model of how the medicines will work in humans.
All three of the vaccines were found to be safe and protected the monkeys against infection with the virus, according to the report published in Science.
The urgency for a vaccine to protect against Zika infection has intensified as the virus spreads rapidly across Latin America and the Caribbean. This week an unprecedented travel advisory was given for southern Florida after more than a dozen people were diagnosed with Zika after being bitten by “homegrown” mosquitoes.
Zika virus is most dangerous to pregnant women, because it can cause severe birth defects in babies if they are infected in the womb.
Right now, just one of those three vaccines will be progressing to clinical trials. That vaccine — dubbed ZPIV for purified inactivated Zika virus — uses a more traditional vaccine approach and depends on dead virus particles.
To develop the vaccine, researchers kill the virus with chemicals, leaving behind harmless proteins that the body can learn to recognize as foreign invaders. Using those proteins as targets, the immune system can then produce antibodies to latch onto live virus particles and destroy them. This kind of vaccine is much safer than ones that depend on live virus particles to foster immunity.
Beyond that, “this is a promising [vaccine] candidate that can be easily produced in large quantities,” said coauthor, Col. Nelson Michael, an Army doctor who specializes in flaviviruses, such as Zika and dengue.