Phase 1b/2 study of a Modified Vaccinia Ankara vectored Zika Vaccine to assess safety in previously flavivirus exposed healthy adults.

Zika virus is a common mosquito spread viral infection that usually causes mild fever but in pregnant women may damage the unborn baby and cause major disability. Children are born with small heads and suffer intellectual and physical impairment. This has been a particular problem in south and central America in recent years but zika infection is also present in many countries in tropical regions. No treatment for zika virus infection is available thus prevention by vaccination is desirable. However any vaccine should be safe to use in young and pregnant women to safeguard the mother and child from harm. We have designed and produced a zika vaccine by incorporating bits of the zika virus genetic code in a smallpox vaccine. The smallpox vaccine has been chosen as it has been used to make other vaccines previously, it has a strong track record of safety and this particular vaccine cannot make copies of itself when injected in a human and therefore should to be safe when used in pregnancy. MVA is not owned by anyone, therefore the vaccine manufacture should prove relatively inexpensive and the vaccine made available at a price suitable for low and middle income countries. The bits of the zika vaccine that have been included incorporate several components that allow the immune system to generate multiple immune responses, which we believe will provide a more protective vaccine and work better in areas of the world where zika circulates. Our vaccine is known as MVAZIKAB. It has completed laboratory studies prior to use in humans and to date has been shown to produce a strong immune response that protects against zika infection in mice. It has been manufactured so it is now suitable for use in humans. We will undertake the immunisation of the first healthy volunteers in early 2022\. If as we expect these initial studies prove safe we will extend the study to increase the number of healthy volunteers to get a better understanding of immune response. However and importantly, we will give the vaccine to a small number of healthy volunteers who have been exposed to other infections similar to zika. This will be a common occurrence if we are to use this vaccine in areas of the world where zika circulates and ensuring safety and immune response in this group will provide reassurance for further studies in endemic regions of south America.