Nikhil Prasad Fact checked by:Thailand Medical News Team Jan 09, 2026 14 hours, 30 minutes ago
Medical News: Milder COVID Linked to Hidden TB Infection
Fresh research from scientists at Aga Khan University Karachi, Dow University of Health Sciences, and the Karolinska Institute Sweden has uncovered an unexpected twist in the COVID-19 story. Individuals quietly living with latent tuberculosis infection sometimes called LTBi… a dormant form of TB that causes no illness appeared far less likely to develop severe COVID-19 symptoms than those without it.
Study suggests dormant tuberculosis may help defend against severe COVID-19 in high TB regions
This finding emerges from a cross-sectional investigation of 275 adults recruited between 2022 and 2023 in Karachi Pakistan at a time when Omicron variants were circulating widely. This
Medical News report offers rare insight from a high TB-burden country where the overlap of the two diseases is unavoidable.
Dormant TB Common Yet Surprisingly Helpful
The researchers found that 32 percent of healthy individuals carried latent TB compared to 18 percent of those infected with COVID-19. Statistical modelling suggested people with LTBi had a 54 percent lower chance of catching COVID-19 at all and when they did every single LTBi positive case experienced only ambulatory mild disease. Not one LTBi positive participant required hospital care.
The team screened participants using the X DOT TB ELISpot blood test and confirmed that a BCG vaccination scar offered no measurable protection. Instead, the shield appeared linked to the body’s existing immune training from exposure to Mycobacterium tuberculosis.
Immune Cells Tell a Deeper Story
A closer look at blood samples showed meaningful differences. Among those with LTBi who avoided hospitalization the immune system displayed stronger T cell patterns tied to MTB compared to hospitalized patients. Individuals suffering severe COVID-19 showed dramatically reduced MTB-responsive interferon gamma producing T cells signals that the viral infection may suppress the body’s wider defenses.
The team also measured key immune genes. COVID-19 patients expressed more OAS1, MAVS, and SOCS3 genes than healthy controls suggesting the immune system was actively fighting the virus. Most striking was that OAS1 levels were highest in LTBi positive COVID-19 patients possibly pointing to a form of immune priming that keeps disease milder.
Antibodies Rise but TB Does Not Change Them
COVID-19 patients produced strong antibody responses against the virus spike protein but LTBi status made no difference to antibody quantity or strength. Even responses to rubella vaccination another unrelated virus remained unchanged showing TB exposure influences cellular immunity rather than antibody immunity.
Conclusion
This detailed work suggests people exposed previously to tuberculosis may carry a trained immune state that softens the impact of new viral threats. In simple terms infection by one microbe could teach the body lessons tha
t later blunt the severity of another. The findings add weight to the idea that real world immunity in crowded regions is shaped by continuous pathogen exposure. However, scientists caution that these results apply to Pakistan’s unique setting and larger multi country studies are needed before firm conclusions can be drawn.
The study findings were published in the peer reviewed journal PLOS One.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0339240
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Read Also:
https://www.thailandmedical.news/articles/coronavirus
https://www.thailandmedical.news/articles/long-covid
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