A promising Zika vaccine is showing complete effectiveness in monkeys, according to a new study, crossing an important hurdle on the way to human trials. But what's most remarkable about this vaccine is that it's far from unique.
Since January, at least half a dozen different Zika vaccines have been rapidly developed in the US alone, with even more being researched around the world. The fact that many of these vaccines are already at an advanced trial stage or being tested on humans in such a short time frame is a feat. This breakneck pace of development is thanks in part to Zika being particularly susceptible to vaccine, but it's also due to an important lesson scientists learned the last time they tried to cure a global outbreak: the 2014 Ebola outbreak in West Africa.
"The same people that were working on Ebola are now working on Zika and we don't want the same thing to happen again, that by the time we have an effective counter-measure, it's almost too late," Col. Nelson Michael, a medical doctor and research who is currently part of a team of scientists developing a Zika vaccine at the Walter Reed Army Institute of Research.
"Everyone is doing what they do best, and we're all working together," Michael told me over the phone. "We're all sharing [data]. This time around we got it right, because that wasn't necessarily true in the Ebola work."
Michael's team published the promising monkey trial results from their vaccine Thursday in research journal Science. The team took a group of 16 monkeys, inoculated half of them with the Zika vaccine and half with a placebo, then injected them all with the Zika virus. All of the unvaccinated monkeys had detectable levels of the virus after exposure, while none of the vaccinated monkeys did. These results bolster an earlier trial on mice that also showed complete protection. Michael said the vaccine will now be headed to a Phase I human trial to make sure it's safe and effective for people.
"The chance that we're going to have a Zika vaccine is very, very high."
Michael and his team's vaccine is a purified inactivated virus vaccine, which means that a dead version of the virus is injected into the body to provoke an immune response. But there are lots of different kinds of vaccines in development right now, such as a DNA vaccine created by the National Institute of Allergy and Infectious Diseases, which started human trials this week.
"All of these are common ways of making vaccines, and all of these Zika vaccines worked in nonhuman primates," Michael told me. "The chance that we're going to have a Zika vaccine is very, very high."
He explained that the Zika virus is a good candidate for vaccines because it provokes an immune response in humans and once you've had it, you typically don't get it again. That means that a vaccine which provokes a similar immune response should protect you from getting sick, and so far that seems to be true.
But besides being a relatively simple virus to attack (compared to, for example, HIV), Michael said the collaboration between different researchers has been key to the fast paced development of these vaccines.
"A lot of times, academic groups compete with each other. That's totally not been the case with Zika," Michael told me over the phone. "Everyone is sharing, and sharing quickly, and it really has been a pretty remarkable story for collaboration."