- Practice abstinence defined as refraining from heterosexual intercourse from 30 days before first vaccination until at least 60 days after 2nd vaccination 10. Female subjects must agree to not donate eggs (ova, oocytes) from the start of screening period until at least 60 days after receiving the last vaccination 11. Subjects must provide concurrent consent at the time of enrollment and 1st vaccination to future use of stored blood samples to measure immunity to ZIKV