On the potential for cross-protection of Zika and Dengue from the Japanese encephalitis vaccine

Currently there is no vaccine for Zika or Dengue Fever that is available in the U.S. This is unfortunate because Zika and Dengue are both common diseases that cause very unfortunate health effects. Yellow Fever, Dengue Fever, Japanese encephalitis, West Nile viruses, and Zika virus are all part of the same family of viruses called flaviviruses that are spread by mosquitoes. Fortunately, there is a very safe and effective vaccine available for Japanese encephalitis.

Can the Japanese encephalitis vaccine provide protection against these other flaviviruses?

This idea is not without precedent. The first vaccine ever, the smallpox vaccine, was actually just cow pox, a weaker cousin of smallpox. And by the way, the modern smallpox vaccine, having lost its usefulness now that smallpox is eradicated, was recently brought back into production to fight monkey pox, another weaker cousin to smallpox.

Regarding JE, Zika and Dengue crossover, there was a study done on this recently to learn preliminary information (Tarbe et al. 2020). Here is the overview:

1. The study was on mice--not humans

2. There is some indication from this and other studies [1,2] that there is cross-reactivity of JE antibodies to Zika virus in mice

3. The researchers conclude that the JE vaccine does provide some protection against Zika

References

1. Tarbe M, Dong W, Hu G, Xu Y, Sun J, Grayo S, Chen X, Qin C, Zhao J, Liu L, Li X, Leng Q. Japanese Encephalitis Virus Vaccination Elicits Cross-Reactive HLA-Class I-Restricted CD8 T Cell Response Against Zika Virus Infection. Front Immunol. 2020 Sep 25;11:577546. doi: 10.3389/fimmu.2020.577546. PMID: 33101303; PMCID: PMC7546338.

2. Zhang W, Xu Y, Zhao F, Tarbe M, Zhou S, Wang W, et al. The pre-existing cellular immunity to Japanese encephalitis virus heterotypically protects mice from Zika virus infection.Sci. Bullet. (2019) 65:6 10.1016/j.scib.2019.11.006