FRIDAY, Dec. 14 (HealthDay News) -- Older people's immune systems are still strong enough to fight off viruses, according to a new study.

Researchers found that specialized immune cells called T cells can respond to virus infections in older people with the same strength as T cells from younger people.

"For a long time, it was thought the elderly were at a higher risk of infections because they lacked these immune cells, but that simply isn't the case," study principal investigator Jonathan Bramson said in a news release from McMaster University, in Hamilton, Ontario.

"The elderly are certainly capable of developing immunity to viruses," he added.

Bramson and his colleagues looked at how the immune systems of people in three different age groups (younger than 40, 41 to 59, and older than 60) responded to infections with three different viruses, including West Nile virus.

In all three groups, both the number and functioning of the T cells were the same, according to the study, which was published Dec. 13 in the journal PLoS Pathogens.

"So as we age, our bodies are still able to respond to new viruses, while keeping us immune to viruses we've been exposed to in the past," Bramson said.

The findings may have an important impact on vaccinations for seniors, according to Bramson. Currently, vaccines for the elderly aren't designed to trigger responses from T cells, which might explain why flu vaccines may fail to provide effective protection for seniors, he said.

He suggested that vaccines specifically designed to generate T-cell immunity may be more effective at protecting seniors.

More information

The U.S. National Institute on Aging has more about vaccinations for seniors.