Researchers from Johns Hopkins Bloomberg School of Public Health have found that the risk of acute lower respiratory infection (ALRI) was reduced in children vaccinated with bacille Calmette-Guerin (BCG).

BCG is a vaccine for tuberculosis. According to the CDC, the vaccine is not generally recommended for use in the United States “because of the low risk of infection with Mycobacterium tuberculosis, the variable effectiveness of the vaccine against adult pulmonary TB, and the vaccine’s potential interference with tuberculin skin test reactivity.”

However, the Johns Hopkins study, which was published in Pediatrics, is based on an evaluation of data from the Macro International Demographic and Health Surveys, as well as the United Nations Children’s Fund Multiple Indicator Cluster Surveys. Lead researcher, Maria-GraciellaHollm-Delgado, PhD, used the data to determine if vaccination with BCG affects the risk of ALRI in children aged 5 years or younger.

The data revealed that there was a 17% to 37% reduction for the risk of ALRI when patients were vaccinated with BCG. However, diphtheria, tetanus-acellular, pertussis, (DTaP) modified the effect of BCG (P<.001). The sequence in which the vaccines were received also was a consideration.

“Protection was amplified if children were co-vaccinated against DTaP with order of vaccine administration playing a central role in the magnitude of this effect,” GraciellaHollm-Delgado said in a released statement. “Although the number of DTaP doses did not modify the effectiveness of BCG against suspected ALRI, increased reactivity to both tuberculin and DTaP antigens after BCG vaccination has been shown in other studies,” GraciellaHollm-Delgado adds.

According to researchers, the study supports the association of BCG vaccination with ALRI and suggests DTaP vaccination may play a key role in amplifying this effect.