COVID-19 and tuberculosis reactivation: a systematic review assessing most common risk factors

COVID-19 as a pandemic not only shifted the focus of the healthcare system from other diseases but also affected the disease progression of infections like tuberculosis which remained a leading killer in the past worldwide. COVID-19 itself is said to reactivate latent tuberculosis as shown in animal experiments. Immunomodulators such as corticosteroids and tocilizumab which are being used for covid treatment even further predisposes patients to tuberculosis reactivation and increased progression of the disease. Diabetes is already known to be a risk factor for tuberculosis reactivation and impact tuberculosis progression and worsen the situation. The exact mechanism of interaction of covid-19 and tuberculosis and their effect on each other remains unknown. Considering high prevalence of tuberculosis and the current scenario of covid-19 in world, there is need to study the impact of covid-19 infection on tuberculosis progression or reactivation and commonly associated risk factors. We conducted a systematic search of the online databases to collect data of patients who had tuberculosis reactivation or increased progression of disease after covid-19 infection. Data of a total of 18 patients was retrieved and used for the syntheses of the study. Diabetes was present in 50% of the patients. 55.5% patients were administered corticosteroids for covid-19 treatment later presenting with tuberculosis. Tocilizumab however was administered to 22.2% patients who also received corticosteroids. 27.7% patients suffered tuberculosis reactivation after covid-19 infection without history of diabetes and corticosteroid or tocilizumab administration. None of the patients were reported to have HIV infection. Major risk factors present in patients included corticosteroid administration and diabetes. However, tuberculosis reactivation was seen even in absence of these factors indicating that covid-19 infection may itself be responsible for tuberculosis reactivation. The exact mechanism however remains unknown and further clinical studies are needed to know the same.