The Effect of Live-Virus Vaccines on Tests for Tuberculosis Infection During the US Immigration Medical Examination: Are Vaccines Causing False-Negative Results?

TL;DR

This study found no evidence that live-virus vaccines lead to false-negative tuberculosis tests in children during immigration medical exams.

Contribution

The study challenges the recommendation to delay tuberculosis testing after live-virus vaccination by analyzing a large dataset of immigrant children.

Findings

Children tested during the critical postvaccination interval had higher IGRA positivity rates than those tested after or before.

Tuberculin skin test positivity was significantly higher in children tested during the critical interval compared to those tested after or before.

The data suggest that delaying tuberculosis testing after live-virus vaccination may not be necessary.

Abstract

It is not recommended to perform tuberculin skin tests (TSTs) or interferon-γ release assays (IGRAs) in the 4 weeks following live-virus vaccination because these vaccines are thought to increase the risk of false-negative results.

We retrospectively analyzed TST and IGRA results for 158 484 US-bound immigrant and refugee children aged 2–14 years who received a required medical examination and live-virus vaccines (measles, mumps, rubella; oral polio; or varicella) overseas during 2014–2022. We created logistic regression models to assess the association between test positivity and vaccination during the critical interval (1–28 days after live-virus vaccination) versus after or before, adjusting for sex, age group, country of examination, and other factors.

The percentage of positive results and the adjusted odds of a positive IGRA result were higher for children tested during the critical interval (4.6%) than for those tested after (3.5%) (adjusted odds ratio, 1.27 [95% confidence interval, 1.13–1.43) or before (3.3%) (1.26 [1.13–1.41]). The percentage of positive results and the adjusted odds of a positive TST were also higher for children tested during the critical interval (15.7%) than for those tested after (7.2%) (adjusted odds ratio, 2.40 [95% confidence interval, 1.79–3.22]) or before (6.6%) (3.81 [2.80–5.18]).

The concern that recent administration of live-virus vaccines leads to false-negative TST and IGRA results is not supported by these findings. Instead, we observed a modest increase in positive results among children tested during the critical postvaccination interval, challenging the need for the testing delay.