An experimental Zika vaccine developed by scientists at the National Institute of Allergy and Infectious Diseases is safe and induces an immune response in healthy adults, according to findings from an early stage clinical trial published Monday in The Lancet, a medical journal.  Interactive toolDaily Florida Zika Tracker The DNA-based experimental vaccine is now in the second phase of clinical trials to determine its safety and effectiveness at preventing infection with Zika virus. Government scientists with the NIAID, part of the National Institutes of Health, developed the experimental vaccine soon after a 2015 outbreak of Zika in northwest Brazil revealed that infection during pregnancy could lead to birth defects. Never miss a local story. Sign up today for a free 30 day free trial of unlimited digital access. SUBSCRIBE NOW Scientists developed the experimental vaccine, which includes a small piece of DNA called a plasmid, by inserting genes into the plasmid that encode two proteins found on the surface of the Zika virus. After the experimental vaccine is injected into muscle, the body produces proteins that mimic the Zika virus and trigger the body’s immune response. Researchers tested two different versions of the vaccine and found that healthy adult volunteers tolerated them well in both trials, although some participants who received injections reported feeling tenderness, swelling and redness at the injection sites. Other participants received the vaccine from a needle-free injector that pushes fluid into the arm muscle. All participants received two or three 4-milligram doses of the experimental vaccine. Scientists then analyzed blood drawn from the participants four weeks after their final vaccinations. They found that 60 to 89 percent of the participants generated an immune response to one version of the experimental vaccine while 77 to 100 percent of the volunteers showed an immune response to the second version. Participants who received the second version of the experimental vaccine via the needle-free injector all generated an immune response and had the highest levels of Zika-neutralizing antibodies in their blood. Scientists also found that