Mycobacterium tuberculosis growth control by peripheral blood mononuclear cells from household contacts is not affected by recent SARS-CoV-2 infection

How recent SARS-CoV-2 infection affects the outcome of Mtb infection is unknown. We performed an Mtb killing assay on peripheral blood mononuclear cells (PBMC) from household contacts (HHC) with recent SARS-CoV-2 (COV^posHHC), without recent SARS-CoV-2 (COV^negHHC), and people with active TB and recent SARS-CoV-2 (COV^posTB^pos). Participants from Cape Town, South Africa were classified by anti-S antibody, anti-N antibody and polymerase chain reaction on nasopharyngeal swab. We infected 3x10⁶ PBMC from each with 3000CFU of Mtb H37Rv for 4 days then inoculated them into Bactec MGIT tubes. <fig><object-id>erj;64/suppl_68/OA1977/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> There was no difference in time to detection (TTD) or normalised growth ratios between groups, even when infected cells were cultured with autologous time-matched serum. A linear model found better control in the coinfected group. Extracellular Mtb in supernatants did not differ between groups. Of uninfected PBMC, 5 (14.3%) were positive. <fig><object-id>erj;64/suppl_68/OA1977/F2</object-id><object-id>F2</object-id><object-id>F2</object-id><graphic></graphic></fig> Therefore recent SARS-CoV-2 does not affect the Mtb killing ability of circulating monocytes <italic>in vitro</italic> and is unlikely to affect the outcome of Mtb infection by this mechanism.