# Projected Effects of Changing Global Tuberculosis Epidemiology on Mycobacterium tuberculosis Immunoreactivity Prevalence, 2024–2050

## TL;DR

This study projects how global TB trends will affect TB immunoreactivity and risk among immigrants to low-incidence countries from 2024 to 2050.

## Contribution

The study introduces a novel projection model linking global TB trends to immigrant TB risk and immunoreactivity.

## Key findings

- M. tuberculosis immunoreactivity prevalence in the Philippines is projected to decline from 40.1% in 2024 to 23.0% by 2050.
- Accelerated ARI reductions lead to greater relative decreases in TB risk than in immunoreactivity prevalence.
- Global TB incidence decline could inform cost–benefit analyses for future TB screening in low-incidence countries.

## Abstract

We assessed how evolving global tuberculosis (TB) trends might influence Mycobacterium tuberculosis immunoreactivity and TB risk among persons immigrating to low-incidence countries. We projected annual risk for infection (ARI) in 168 countries for 2024–2050, focusing on China, India, the Philippines, and Vietnam. We applied projections to the age profile of immigrants to 4 low-incidence countries to estimate changes in M. tuberculosis immunoreactivity prevalence and TB risk under status quo and accelerated ARI decline scenarios. In the status quo 2024 estimate, M. tuberculosis immunoreactivity prevalence ranged from 14.7% in China to 40.1% in the Philippines, declining to 5.8% in China and 23.0% in the Philippines by 2050; TB risk also declined. Accelerated ARI reductions yielded greater relative decreases in disease risk than immunoreactivity prevalence. Declining global TB incidence could reduce M. tuberculosis immunoreactivity and disease risk among immigrant populations, which could inform cost–benefit analyses for future TB screening strategies in low-incidence settings.