Researchers in the United States have successfully infected human volunteers with the Zika virus, marking a significant step towards understanding the disease, as well as developing vaccines and treatments. This groundbreaking study, known as a “controlled human infection model,” has previously been deemed controversial due to the risks involved and the lack of effective treatments. However, both U.S. regulators and the World Health Organization have approved and recognized the safety and importance of this new model, which was developed by a team at the Johns Hopkins Bloomberg School of Public Health.
Zika is a viral infection primarily transmitted by mosquitoes and is typically mild or asymptomatic. However, a major outbreak in the Americas between 2015 and 2016 revealed its potential dangers to pregnant women and their unborn babies, causing severe birth defects such as microcephaly, characterized by an abnormally small head and brain. Despite the absence of vaccines and treatments, the outbreak subsided before new ones could be thoroughly tested. The number of reported Zika infections globally has decreased since then, with approximately 40,000 cases reported from the affected region last year. Nevertheless, the World Health Organization has cautioned that surveillance efforts are sometimes inconsistent, and transmission patterns for Zika are still not well understood. The spread of Zika is also anticipated to increase due to climate change, and the virus is currently present in 91 countries.
Leading the study, Professor Anna Durbin from Johns Hopkins emphasized the importance of developing countermeasures, as there is a possibility of a resurgence in Zika cases. Additionally, she highlighted the mental health burden carried by pregnant women in endemic areas, who are concerned about the virus and their infants but have limited protection options.
In the study, Durbin and her colleagues infected 20 non-pregnant and non-lactating female volunteers with two strains of Zika. All participants developed laboratory-confirmed infections, but the illnesses were mild. Eight other participants received a placebo. To minimize risks, the infected patients were placed in an inpatient unit and closely monitored until the virus was no longer present. They also agreed to use birth control methods for two months.
The subsequent phase involves evaluating the strains in male volunteers, partly to ascertain how long the virus remains infectious in semen, as sexual transmission is possible. Durbin revealed that multiple vaccine manufacturers have already expressed interest in using these strains to test their experimental products.
The data from this study was presented as an abstract at the annual meeting of the American Society of Tropical Medicine and Hygiene held in Chicago.
(Reporting by Jennifer Rigby; Editing by Clarence Fernandez)
