Kohortstudie om varigheten av BCG-vaksinens beskyttelse

Tuberculosis (TB) remains a major preventable cause of morbidity. Bacillus Calmette Guerin (BCG) vaccines are widely used to protect against TB. Their efficacy shortly after vaccination has been demonstrated, but the duration of protection is not well known. This information is needed to inform BCG vaccination policies and can help to assess the cost of BCG vaccination against its effectiveness in the society. This study will measure the duration of BCG protection against TB and estimate changes in efficacy with time since vaccination. We will use historical population data to compare the frequency of TB occurrence in people who received the BCG and those who did not, at various period after vaccination.