Has the COVID-19 pandemic increased tuberculosis mortality?

In October, 2021, WHO estimated that—because of the COVID-19 pandemic—global deaths from tuberculosis had increased for the first time in a decade. This estimate of increased mortality has been widely interpreted as an objective fact. But it is important to point out a footnote published with these estimates: “To estimate the impact [of COVID-19 on tuberculosis]…models were developed for…16 countries…and a statistical model was used to extrapolate results to other low- and middle-income countries. The most important assumption was that reductions in notifications of people diagnosed with tuberculosis reflected real reductions in the number of people with tuberculosis who accessed treatment”.

In other words, if reductions in tuberculosis notifications were fully driven by reduced health-care access, then tuberculosis mortality has increased during the pandemic. But if lower notifications also (even partly) reflect reductions in transmission of Mycobacterium tuberculosis, it is possible that the effect of the pandemic on tuberculosis mortality has been overestimated. A separate model found that if lockdowns and other measures substantially reduced M tuberculosis transmission, overall tuberculosis incidence (if not mortality) could fall as a result of the pandemic. Furthermore, although pandemic-related restrictions are unlikely to have reduced household transmission, most M tuberculosis transmission in high-burden settings probably occurs outside the household. Additionally, there is indirect evidence that pandemic measures reduced respiratory contact rates, as the incidence of influenza and other respiratory viral illnesses plummeted in 2020. Thus, it is at least a reasonable possibility that measures taken in response to the COVID-19 pandemic—through policy or behaviour change—had a salutary effect on transmission of M tuberculosis.

In summary, there can be no question that the COVID-19 pandemic has devastated global systems for tuberculosis control. But in doing so, it is possible that the pandemic has also dealt a blow to transmission of the pathogen. As such, although it is likely (if not proven) that the COVID-19 pandemic has substantially increased tuberculosis mortality, it is also possible that tuberculosis incidence has genuinely declined. If we can move urgently to strengthen systems for finding, treating, and preventing tuberculosis, it is possible that global targets for ending tuberculosis are more achievable than ever before. But if we fail to act on tuberculosis in 2022, it seems almost certain that increases in mortality will be transformed from modelled estimates to reality.

I declare no competing interests. This letter was written with support from a Catalyst Award from Johns Hopkins University.