Phase two testing of an experimental DNA vaccine designed to protect against disease caused by Zika infection is underway. The vaccine was developed by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH).
“Zika virus will likely become endemic in years to come, so a safe and effective vaccine is an important goal of our work,” said Anthony S. Fauci, MD, director of NIAID, during a press conference on March 31.
To date, the CDC reports 5,234 Zika virus disease cases in the United States and 36,526 cases in U.S. territories.
Here are five things MCOs should know about the trial.
1. The trial’s purpose.
The two-part phase 2 trial, called VRC 705, consists of parts A and B. Part A, which began in late March, will build on ongoing phase 1 trials and will continue to evaluate the vaccine’s safety and ability to stimulate an immune response—specifically in populations where Zika could be endemic. It will also help to determine the optimal dosage and ideal injection sites. Part B, which will begin in May or June, aims to determine if the vaccine can effectively protect against Zika-related disease when someone is exposed to the virus.
2. Who can enroll and what the trial will entail.
Part A will enroll 90 healthy men and nonpregnant women between the ages of 18 and 35 at three sites in Houston, Miami, and San Juan, Puerto Rico. All participants will receive the investigational vaccine via an injection in the muscle at three separate clinic visits four weeks apart. Participants will randomly receive either a standard dose or a high dose of the investigational vaccine, and will be followed for about 32 weeks.
Part B of the trial will enroll at least 2,400 healthy men and nonpregnant women between the ages of 18 and 35. Sites will include the three locations from part A as well as two additional sites in San Juan, two sites in Costa Rica, and one site each in Peru, Brazil, Panama, and Mexico. Additional sites might be added. Participants will randomly receive either the investigational vaccine or a placebo.
Part B participants will be followed for almost two years, and assessed for adverse reactions and symptoms of Zika infection. “Participants will provide blood and urine samples regularly, so investigators can measure immune response and track any Zika infections,” Fauci said. Investigators will compare the rates of confirmed cases of Zika in the placebo group and the vaccinated group to determine if the investigational vaccine protects against disease caused by Zika infection.
3. What has been studied so far and what the findings are.
After extensive testing in animals, early-stage human testing began in 2016. Initial findings indicated that the vaccine is safe and able to induce a neutralizing antibody response against Zika virus. “The immune responses we’re getting look quite good so far, but we want to get more results,” Fauci said.
4. When the trial will conclude.
“Completion of the trial depends on the intensity of Zika virus transmission and efficacy of the vaccine candidate,” Fauci said. “Initial results could be available as early as the end of 2017.” The study is expected to conclude in 2019.
5. The status of funding.
The trial will cost approximately $100,000 million; funds have already been allocated for phase 2, Fauci said. Results from these trials will indicate if a phase 3 trial is necessary. However, he could not guarantee that funds would be available for a third phase since NIAID’s budget is in the government’s hands.
Karen Appold is a medical writer in Lehigh Valley, Pennsylvania.