A study, published in the journal CHEST, examined critical illness outcomes in patients vaccinated with the trivalent influenza vaccine to unvaccinated patients.
Researchers reviewed 72 reported cases of seasonal influenza requiring hospitalization at a community teaching hospital between September 2015 and April 2016. Out of the 72 cases, 51 patients tested positive for H1N1 influenza A virus. Researchers also examined: age; mortality rate; intensive care unit admission; ICU length of stay; smoking status; sepsis; acute kidney injury; multi-organ dysfunction syndrome; acute respiratory distress syndrome; and mechanical and non-invasive ventilation.
Here are six study findings:
1. Unvaccinated patients were younger with a mean age of 59.6 years compared to 70.4 years among the vaccinated group. The unvaccinated group also displayed a lower prevalence of smoking.
2. Acute kidney injury risk was higher in unvaccinated patients — 35 percent versus 6 percent in vaccinated patients.
3. Vaccinated patients experienced a higher need for noninvasive ventilation, whereas unvaccinated patients displayed a higher need for mechanical ventilation and multi-organ dysfunction syndrome.
4. Twice as many unvaccinated patients needed mechanical ventilation, due to higher prevalence of acute respiratory distress syndrome.
5. The tendency toward ICU admission was higher in the unvaccinated group compared to the vaccinated group.
6. However, there was no difference in mortality, shock/vasopressor support and ICU length of stay between the two groups.
"Vaccinated patients with influenza A(H1N1) requiring hospitalization tend to have better outcomes than unvaccinated patients," study authors concluded.