BCGvaksinen

BCGvaksinen, known in English as the BCG vaccine, is a live attenuated vaccine derived from Mycobacterium bovis. It was first introduced in 1921 by Albert Calmette and Camille Guerin and has since become the most widely administered vaccine worldwide. The primary purpose of BCG vaccination is to protect against severe forms of tuberculosis (TB), particularly tuberculous meningitis and miliary disease in children. In adults, the vaccine offers limited protection against pulmonary tuberculosis but can reduce dissemination of the disease.

The vaccine is usually given intradermally, often at birth or within the first few months of life in high‑risk countries. In many low‑ to middle‑income nations, a single dose is part of the national immunization schedule, while in countries with low TB incidence, BCG is typically reserved for individuals at high risk, such as healthcare workers or contacts of TB patients. WHO recommends universal BCG vaccination in countries where TB prevalence is high and recommends targeted use where prevalence is lower.

Efficacy of BCG varies geographically, ranging from negligible to about 80% protection against TB meningitis and peritonitis in children. Randomized trials have shown inconsistent effectiveness against pulmonary TB. Common side effects are mild and include local ulceration, ulceration with scarring, and regional lymphadenitis. Rare complications can involve disseminated BCG infection, especially in immunocompromised individuals.

The vaccine’s mechanism involves stimulating both innate and adaptive immune responses, promoting Th1‑type immunity and the formation of granulomas. Ongoing research explores new vaccine candidates that may overcome the variable efficacy of BCG and provide broader protection against TB strains.