With the onset of the flu season, the first protection for seniors, who are considered among the most vulnerable, is the flu vaccine. However, a new study says the vaccine is less beneficial and may not protect older people from pneumonia after they have the disease.

Researchers collected data on 1,173 people between 65 and 94 who had pneumonia. These individuals were compared with 2,346 people who did not get pneumonia. Both groups had similar rates of flu vaccination over three seasons of studies, the researchers say.

The researchers found that vaccinated seniors who caught the flu were as likely to develop pneumonia as unvaccinated seniors who caught the flu.

Seniors with chronic diseases, like lung disease, heart disease and diabetes, are more susceptible to getting flu that could develop into pneumonia if they are vaccinated.

Lead researcher Michael L. Jackson, a postdoctoral fellow at the Group Health Center for Health Studies in Seattle still recommends that seniors get the flu vaccine. He said the vaccine helps reduce the risk of flu in healthy seniors. The report is published in the Aug. 2 issue of The Lancet.