A new study, led by the London School of Hygiene & Tropical Medicine in the United Kingdom, found the Bacillus Calmette-Guérin vaccine for tuberculosis is effective for at least 20 years, higher than the 10 to 15 years that researchers previously believed.
The Bacillus Calmette-Guérin vaccine is currently the only vaccine for TB.
Researchers studied adults in England 10 to 30 years after they were offered the BCG vaccine at school. Around 75 percent of cases were vaccinated, as compared to 86 percent who were the controls. Researchers compared 677 cases of people who were diagnosed with TB and 1,170 people without a previous TB history.
The study shows BCG's protective effect declines after 20 years. It also shows that 10 to 20 years later, vaccinated individuals were less than half as likely to contract TB compared to those who were not vaccinated. Researchers found the vaccine protected recipients around 13 years old from contracting the infection in their adulthood, when infection was more likely.
"Previous studies have shown BCG can offer good protection against TB for up to 10 to 15 years following vaccination of secondary schoolchildren, but we do not know the duration of protection in different populations. Our study showed it offers moderate protection for longer than had been recognized," said Dr. Punam Mangtani, lead author and associate professor in epidemiology at the London School of Hygiene & Tropical Medicine.