Flu Season Severe for the Unvaccinated

Influenza cases in unvaccinated patients most severe this flu season

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Though the flu strikes every year, each season can be different. Researchers behind a new study uncovered some surprising trends about this season's flu.

The researchers focused on patients who were treated for the flu this season at Duke University Hospital in North Carolina.

This study showed that of the patients who became critically ill with the flu, most of them had not received a vaccination.

"Talk to your doctor about flu vaccination."

The researchers, who were led by Cameron Wolfe, MD, of Duke Medicine at Duke University in Durham, North Carolina, looked at patients who were treated at Duke University Hospital for the flu between November 1, 2013 and January 8, 2014.

In total, 55 patients were identified, and the researchers noted that rates of more severe cases increased in recent weeks.

Demographic details, vaccination history and the nature of the patients' illness were all explored. The average age of the patients was 28.5 years old.

Most of the patients (87.3 percent) were determined to have the H1N1 strain of influenza, which has also been the most commonly seen strain in other reports across the country this season.

Dr. Wolfe and team found that 40 percent of the patients (22 patients) had to be admitted to the intensive care unit (ICU). At the time of the report, three deaths had occurred, and 18 patients were still hospitalized.

Less than a quarter of the patients (23.6 percent) received a flu vaccine at least two weeks before becoming ill.

The rate was even lower among the 22 patients who had to be treated in the ICU — 9.1 percent of this group was vaccinated. In comparison, 33.3 percent of the 33 patients who did not require treatment in the ICU were vaccinated.

Most of the patients who were vaccinated and still became ill had underlying health conditions, including leukemia, hepatitis C and kidney issues. The same was not true for the unvaccinated patients — they were mostly healthy prior to becoming ill with the flu.

In a Duke Medicine news release, Dr. Wolfe said that these findings support recommendations for flu vaccines.

“Our observations are important because they reinforce a growing body of evidence that the influenza vaccine provides protection from severe illness requiring hospitalizations,” said Dr. Wolfe.

"The public health implications are important, because not only could a potentially deadly infection be avoided with a $30 shot, but costly hospitalizations could also be reduced," he said.

This study had a small sample size and focused on one hospital. Further research is needed to confirm these findings in a larger population.

The study was published online February 10 in the American Journal of Respiratory and Critical Care Medicine. No conflicts of interest were reported.

Review Date: 
February 10, 2014
Last Updated:
February 11, 2014