Influenza vaccination shows mixed results on all-cause mortality in patients with ILD
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Among patients with interstitial lung disease, those who received an influenza vaccination demonstrated a significant reduction in all-cause mortality in two of the four seasons evaluated in a recent study.
Pavo Marijic, MS, of the German Research Center for Environmental Health GmbH, Neuherberg, Germany, and colleagues conducted the study to assess all-cause mortality and all-cause and respiratory-related hospitalization in vaccinated and unvaccinated patients with ILD.
The study involved data from the largest German statutory health insurance fund, which had roughly 27 million insurees in 2020. Researchers assessed four influenza seasons from 2014 to 2015 through 2017 to 2018, comparing vaccinated with unvaccinated patients with ILD. They started from Sept. 1 of each year, matching vaccinated and unvaccinated patients 1:1 using a rolling cohort design.
Results revealed that both the vaccinated and unvaccinated cohorts had 7,503 patients in 2014 to 2015, 10,318 in 2015 to 2016, 12,723 in 2016 to 2017, and 13,927 in 2017 to 2018.
Starting with a vaccination rate of 43.2% in season 2014 to 2015, the number decreased over time to 39.9% in season 2017 to 2018. All-cause mortality risk ratios varied each season: 2014 to 2015, 0.79 (95% CI, 0.65-0.97); 2015 to 2016, 0.66 (95% CI, 0.54-0.8); 2016 to 2017, 0.89 (95% CI, 0.76-1.04); 2017 to 2018, 0.95 (95% CI, 0.81-1.12).
Comparable effects on all-cause hospitalization and respiratory-related hospitalization were observed in all seasons.
“The impact of influenza vaccination has varied across the four seasons investigated, with some years showing very promising results for all-cause mortality,” the researchers wrote. “Although not significant, the risk of hospitalization was also lower in vaccinated patients for those seasons, which underlines the clinical relevance of vaccination. Although group differences appeared only after some time rather than immediately after the vaccination and the sensitivity analysis showed no significant off-season effects for most outcomes, our results should be interpreted with caution because residual confounding may remain.”