NIAID Zika Vaccine Enters Clinical Trial

A DNA Zika vaccine developed by the National Institute of Allergy and Infectious Diseases (NIAID) has entered a clinical trial to evaluate its safety and efficacy. This news comes after the United States Department of Defense (DoD) confirmed more than 30 cases of Zika among US troops.

Currently, Puerto Rico, American Samoa, the US Virgin Islands, and Florida are experiencing active Zika transmission. As of late last night, Florida has had 15 cases of Zika infection that were locally acquired. According to the Florida Department of Health, a total of 55 pregnant women residing in the state have been infected with the virus, either locally or through travel or sex with an infected partner. Furthermore, the DoD confirmed that 33 US troops, including one pregnant woman, were infected with Zika outside of the United States. Recently, the Centers for Disease Control and Prevention added Antigua and Barbuda, as well as Turks and Caicos Islands (in the United Kingdom) to its Zika travel guidance.

There are no available vaccines to protect travelers against the virus. The NIAID Zika virus investigational DNA vaccine, as it is called, was developed in early 2016. According to a press release, “The study is part of the US government response to the ongoing outbreak of Zika virus in the Americas.” The approach used in the development of this vaccine was previously implemented by NIAID in a West Nile virus vaccine, which was found to be safe and effective in Phase I trials.

In the trial, the vaccine will be tested on at least 80 healthy participants between the ages of 18 and 35, who will be randomly divided into four groups of 20. The vaccine will be administered intramuscularly to each of the participants on their first visit to the testing facility. After 8 or 12 weeks of initial vaccine administration, participants in the first two groups will receive a second vaccine shot. The participants in the third group will receive the second vaccine shot at 4 weeks, and a third shot at week 8. The fourth group will receive their second shot at week 4 and their third shot at week 20. Following the administration of each vaccine shot, each participant will remain at the site for 30 minutes under observation for reactions to the vaccine.

The vaccine contains an engineered, non-infectious Zika virus plasmid that “contain genes that code for proteins of the Zika virus.” According to John Mascola, MD, director of NIAID’s Vaccine Research Center (VRC), “DNA or gene-based vaccines include antibodies, but they also can activate the cell-mediated immune response, which ultimately could yield strong and durable protection against disease.”

Study participants will be asked to document their temperature as well as any symptoms, for one week after each vaccine shot. To determine the safety of the vaccine, the study researchers will review daily and weekly data for each study participant, as well as evaluate the overall wellbeing of the participants after 44 weeks of initial vaccine administration. Blood samples will be collected at two follow-up visit to assess “durability of the immune response” to the vaccine: one after 18 months, and a second after 24 months of initial vaccine administration.

Anthony Fauci, MD, director of NIAID stated, “A safe and effective vaccine to prevent Zika virus infection and the devastating birth defects it causes is a public health imperative… NIAID worked expeditiously to ready a vaccine candidate and results in animal testing have been very encouraging. We are pleased that we are now able to proceed with this initial study in people. Although it will take some time before a vaccine against Zika is commercially available, the launch of this study is an important step forward.”

According to the press release, “initial safety and immunogenicity data from the Phase 1 trial are expected by the end of 2016. If results show a favorable safety profile and immune response, NIAID plans to initiate Phase 2 trial in Zika-endemic countries in early 2017.”