BCG not effective in preventing Covid-19 infection in older people

A new study by Eva Koekenbier and team showed that older persons with comorbidities are not protected by the Bacillus Calmette-Guérin (BCG) vaccine from COVID-19, COVID-19 hospitalization, or clinically relevant respiratory tract infections (RTI). The findings of this study were published in Clinical Microbiology and Infection. 

Even while COVID-19 can affect people of any age, older persons are most susceptible to the severe coronavirus illness 2019 (COVID-19), which is linked to significant mortality and morbidity. Before the COVID-19 pandemic, a randomized clinical experiment (ACTIVATE) in Greece found that older persons who received the BCG vaccine after being released from the hospital had a decreased incidence of respiratory tract infections throughout the course of a year-long follow-up. Therefore, in a randomized double-blind placebo-controlled multicenter experiment, researchers investigated whether BCG immunization might lower the prevalence of COVID-19 and other respiratory tract infections in older persons with one or more comorbidities.

Adults over 60 who reside in the community and have one or more underlying comorbidities but no contraindications to receiving the BCG vaccine were randomized 1:1 to get the BCG vaccine or a placebo, and they were then monitored for six months. Self-reported test-confirmed COVID-19 incidence served as the main outcome. Admissions to hospitals for COVID-19 and clinically relevant RTI were secondary goals (i.e. RTI including but not limited to COVID-19 requiring medical intervention). Clinically pertinent RTI events and COVID-19 were judged. Using Fine and Gray regression to take competing events into account, incidences were compared.

The key findings of this study were:

A total of 6,112 people were randomized to receive the BCG vaccine (n = 3,058) or a placebo (n = 3,054), with a median age of 69 years (inter-quartile range: 65-74) and a median of 2 comorbidities (inter-quartile range: 1-3). 

129 BCG participants and 115 placebo recipients both had COVID-19 infections. 

With regard to COVID-19, 18 BCG patients and 21 placebo recipients required hospitalization. 

13 BCG recipients and 18 placebo receivers passed throughout the trial period, with 11 fatalities (or 35%) being linked to COVID-19, with 6 in the placebo group and 5 in the BCG group.

In a sizable cohort of older persons with comorbidities from the Netherlands, BCG immunization did not offer protection against COVID-19 infection and did not lower the prevalence of clinically significant RTI.

Reference: 

Koekenbier, E. L., Fohse, K., van de Maat, J. S., Oosterheert, J. J., van Nieuwkoop, C., Hoogerwerf, J. J., Grobusch, M. P., van den Bosch, M. A. A. J., van de Wijgert, J. H. H., Netea, M. G., Rosendaal, F. R., Bonten, Marc. J. M., Werkhoven, C. H. (Henri) van, Huisstede, A. A., Boersma, W. G., Duijkers, R., Ammerlaan, H. S. M., Peters, V., Bonten, M. J. M., … Slingerland, R. J. (2023). Bacillus Calmette-Guérin vaccine for prevention of COVID-19 and other respiratory tract infections in older adults with comorbidities: a randomized controlled trial. In Clinical Microbiology and Infection. Elsevier BV. https://doi.org/10.1016/j.cmi.2023.01.019