The phase 1 study included 35 healthy women. Those who were given injections of two possible vaccines developed antibodies to the chlamydia bacteria, but a lot more testing is needed before the vaccine would be ready for the public, the researchers added.
“An effective vaccine against chlamydia would have enormous public health and economic impact,” said lead researcher Frank Follmann. He is director of infectious disease immunology at the Center for Vaccine Research at Statens Serum Institute in Copenhagen, Denmark.
“This is a promising first step on the road to develop a vaccine,” he said. “The success of the HPV [human papillomavirus] vaccine has shown us how effective vaccination can be against a sexually transmitted infection. We hope to do the same with chlamydia and, in the long term, combine the two vaccines.”
The results of this study are encouraging, and larger trials are planned, Follmann said. “The goal is to vaccinate girls [and potentially boys] before they become sexually active,” he explained.
One expert said the findings show promise.
“Developing a vaccine against chlamydia has been challenging,” said Fred Wyand, a spokesman for the American Sexual Health Association. “The study gives reason to be hopeful that vaccination to prevent chlamydia will someday be possible, but that goal lies in the future.”
In the meantime, Wyand added, “it’s important to keep in mind that chlamydia is easily diagnosed, treated and cured. This is why it’s so important to test, and experts like the CDC recommend annual chlamydia testing for all sexually active women age 25 and under.”
In the vaccine trial, the women were randomly assigned to one of two different vaccines or a placebo.
All of the women who received the vaccine produced antibodies to chlamydia, but one of the vaccines, called CTH522:CAF01, produced nearly six times more antibodies than the other vaccine, the investigators found.
That’s the formula the researchers think should be pursued. From these results, however, it isn’t a certainty that the vaccine will protect someone from chlamydia or if the protection will last over the long term, the researchers noted.