Chlamydia infections have been very common for a long time. However, not many people know that they can cause very serious health problems. There are currently three types of chlamydia: Chlamydia trachomatis, Chlamydia pneumoniae and Chlamydia psittaci. Information published in Vaccine and ScienceDaily states that the first effective vaccine against one of the chlamydia, Chlamydia trachomatis , has been discovered.