Researchers Encouraged by New Chlamydia VaccineEuropean researchers say a vaccine for chlamydia — the world's most common sexually transmitted disease — shows promise in preliminary clinical trials, but more tests are needed. A study in the medical journal Lancet says the vaccine triggered an immune response in tests on 35 healthy women. The researchers say they must now determine if the vaccine can actually prevent chlamydia. Doctors say a vaccine against the disease would have a huge impact on public health and the economy around the world. "Given the impact of the chlamydia epidemic on women's health, infant health through transmission, and increased susceptibility to other sexual diseases, a global unmet medical need exists for a vaccine," said Peter Anderson, Imperial College of London professor and co-author of the study. Although chlamydia is easily diagnosed and treated with antibiotics, such treatment has failed to curb the epidemic. About 130 million people around the world are infected every year. Untreated, it can lead to pelvic inflammation in women and possible infertility. Chlamydia in pregnancy could cause miscarriage, stillbirth, or premature delivery.