Challenges in testing the effectiveness of vaccines

摘要

Current phase 3 clinical trials will provide vaccine efficiency data for different age groups. As the approved vaccines are rolled out into the population, Phase 3 studies of new or adapted vaccines will become more difficult to carry out. Bridging studies, monitoring correlates of protection, will therefore become more important. The results of the Phase 3 trials will only provide information on the direct effectiveness of the vaccine to prevent disease symptoms. However, as more people are vaccinated, data is emerging on its ability to reduce transmission. Currently available data from various phases of clinical trials indicates a highly divergent immune responses between vaccine platforms.