Flu vaccine may reduce risk for TB
Influenza vaccination may also protect people against tuberculosis, the world’s No. 1 infectious disease killer, according to results from a large nationwide cohort study in Taiwan.
Yung-Feng Yen, MD, clinical physician at Taipei City Hospital, and colleagues found that from 2005 to 2012, the risk for incident TB was 18% lower among elderly patients who were vaccinated against influenza compared with unvaccinated patients.
“Although several reports have indicated a possible interaction between influenza vaccination and TB, little is known regarding the association between influenza vaccine and subsequent TB development,” Yen and colleagues wrote in Emerging Infectious Diseases.
Their population-based cohort study included 99,982 patients aged older than 65 years who were randomly sampled in a research database in the National Health Insurance (NHI) program, which covers more than 99% of Taiwan’s population. The study included 64,290 patients who were vaccinated against influenza — a free service for patients aged older than 65 years in Taiwan since 2001— and 35,692 who were not.
According to the data, in the 9-year follow-up period, there were 145.2 cumulative cases of incident TB per 100,000 person-years among vaccinated patients and 175.5 cases per 100,000 person-years among unvaccinated patients, Yen and colleagues reported. Modeling that adjusted for sociodemographic characteristics and concurrent conditions showed that influenza vaccination was an independent protective factor against incident TB, they said.
“Although influenza vaccination reduced the risk of incident TB by only 18% in an older population, a previous report showed that a relevant vaccine (when given to adults) would reduce the burden of TB, even when the vaccine is only partially effective in protecting against [Mycobacterium] tuberculosis infection. Therefore, our findings suggest that influenza vaccination should be offered to elderly persons to prevent infections,” Yen and colleagues wrote.
The researchers said the lower risk for incident TB in elderly patients who were vaccinated is likely related to T-cell-mediated immunity.
“A particular strength of this study is that we traced all elderly persons with minimal referral bias, because all medical care is covered by the Taiwan NHI program,” they wrote. “Furthermore, the study’s large sample size was sufficiently powered to detect the real, albeit subtle, difference between vaccinated and unvaccinated elderly persons.”
Among the study’s limitations, Yen and colleagues said some potential risk factors like smoking and obesity were not available for analysis.
Yen Y-F, et al. Emerg Infect Dis. 2018;doi:10.3201/eid2403.152071.
Source: Healio
