The Army had moved from recognizing Zika virus as a threat to producing the vaccine to testing it in animals and ruling it safe for human trials in only a 10-month period. as of November 2, there have been 149 cases of Zika infection confirmed in the military health system, including four pregnant service members and one pregnant family member. The volunteers have some assumed risks: sometimes Guillain-Barré syndrome which is an uncommon illness that affects the nervous system manifests as a result of adverse vaccine reactions; 1.6 cases of Guillain-Barré Syndrome were anticipated per million vaccinations. More, vaccination with ZPIV or with any of the other vaccines that are aimed to prevent flavivirus infections could lead to vaccinated service members becoming even more sick if they contracted Zika virus after vaccination. However rhesus monkeys vaccinated with ZPIV developed a “strong immune response” and were protected against two strains of Zika virus.