New Research on Zika Virus Touts Promising Vaccine Candidate

In most trial volunteers, a two-dose regimen of a potential vaccine safely produced antibodies that, when transferred to a mouse, successfully neutralized Zika virus cells.

This 2003 photo shows a female Aedes albopictus mosquito, the type that can spread the Zika virus, acquiring a blood meal from a human host. (James Gathany/Centers for Disease Control and Prevention via AP)

(CN) — A vaccine candidate shows promise against the Zika virus, a currently untreatable infection that caught international attention during a 2015-2016 epidemic, and a new study has found that screening blood for the transfusion-transmissible virus may be an inefficient use of resources.

The pair of new research articles outlining the findings were published Monday in the scientific journal Annals of Internal Medicine. 

When adults are infected by the Zika virus, the resulting Zika fever can cause mild symptoms such as red eyes, joint pain, headaches and rashes — though some patients experience no symptoms at all. Daytime mosquitoes in the Aedes genus spread the virus with their bites.

Zika can also spread from men to women via sex, as the virus can live in semen for months, and there have been some cases of transmission through blood transfusions. Pregnant women can also pass the virus down to their children, who are at heightened risk of severe symptoms.

Children born with Zika may experience microcephaly — the development of an unusually short head, frequently accompanied by intellectual disabilities, stymied motor and speech functions, seizures and other maladies — or suffer severe brain malformations.

In the mid-1900s, Zika was only known to appear in certain parts of equatorial Africa and Asia, though the virus appeared on the island of Yap in 2007 and then in Oceania in 2013. In 2015, the virus reached the Americas: an April 2015 Brazil outbreak spread through South America, Central America and the Caribbean.

A number of Zika vaccines are in development. Two dozen scientists conducted a double-blind, placebo-controlled and randomized study of Ad26.ZIKV.001, a prophylactic vaccine candidate, on 100 adult volunteers.

“The safety and immunogenicity profile makes Ad26.ZIKV.001 a promising candidate for further development if the need reemerges,” the authors wrote in the study.

The researchers say that in at least 80% of the volunteers, a two-dose regimen of the vaccine safely produced antibodies that, when transferred to a mouse, successfully neutralized Zika virus cells.

In another new study, Stanford University researcher W. Alton Russell ran computer simulations to consider the effectiveness of screening blood donations for the Zika virus in the U.S. and compared this to how cost-effective universal screening procedures were in 2018.

His model found that Zika screenings were not a cost-effective way of saving lives, finding that only one congenital case of Zika would occur every 1,484 years if clinics dispensed with the expensive universal screening measures — which cost blood centers an aggregate $8 to $13 million monthly.

The paper aligns with a January 2019 study that estimated that complications from transfusion-transmitted Zika infections are unlikely at just 1.02%. Those scientists recommended that blood screening tests should be conducted in regions where the Zika virus is endemic.

Researchers involved in the new studies did not respond to requests for comment.

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