High-Dose Vaccine May Help Elderly Beat Seasonal Flu

A bigger dose produced more antibodies and was safe, research found

WEDNESDAY, May 24, 2006 (HealthDay News) -- High-dose influenza vaccines may boost immune responses to the seasonal virus in older people, reducing their death risk, researchers report.

Although the elderly are considered particularly at risk each season for flu and are advised to get a flu shot every year, their systems often don't make enough antibodies to give them the highest degree of protection.

"Influenza is a deadly disease for many people, particularly the elderly," said lead researcher Dr. Wendy A. Keitel, an associate professor of medicine at the Influenza Research Center of the Baylor College of Medicine, in Houston. "Most of the people who die from complications of influenza are over the age of 65."

The researchers speculated that by giving high doses of flu vaccine, they could improve the antibody response.

Their report appears in the May 22 issue of the Archives of Internal Medicine.

The current dose of inactivated flu virus in vaccines is 15 micrograms. In their study, Keitel's team looked at the response to vaccines containing 15, 30 and 60 micrograms of virus in 202 people age 65 years and older. Patients were randomly selected to receive one of the three doses or placebo.

The participants were examined 30 minutes, two days and 28 days after the vaccine and were contacted six months later to determine if there were any serious adverse events or side effects.

"The results of the study were promising," Keitel said. "As you increase the dosage level of vaccine from the usual amount to four times that amount, you can stimulate better antibody responses," she said.

Keitel's group found that people who received higher dosages of vaccine had higher concentrations of antibodies. In addition, a large number of those who received the higher-dose vaccines had a sufficient immune response to protect them from developing the flu.

Moreover, all the vaccine dosages were safe and well-tolerated. Discomfort, redness or swelling at the site of the injection was more common among those who received the 60 microgram dose than among those who received the 15 microgram dose, but most reactions were mild, Keitel said.

"We need to continue to explore this promising approach to improve immune responses," Keitel said. "We need to test if this will actually reduce the incidence of influenza in this age group."

One expert thinks the strategy may be worthwhile.

"Considering an increase in dose for the elderly is a reasonable assumption," said Dr. Marc Siegel, a clinical associate professor of medicine at New York University School of Medicine. "The article convinces me that they can cause more antibody response using a higher dose."

Siegel noted that most of the elderly who die from flu die from its complications, such as pneumonia. "The elderly should be getting pneumonia vaccine, not just flu shots," he noted.

In addition, a study is needed to see if higher flu vaccine doses help prevent older adults from getting flu and also reduce the death rate if they become infected, Siegel said.

"This study raises the question that we ought to be looking into the effects of different dosing strategies on patients that may not be immunologically competent, as a way of offering them better protection," he said.

More information

For more on the seasonal influenza vaccine, head to the U.S. National Institute of Allergy and Infectious Diseases.

SOURCES: Wendy A. Keitel, M.D., associate professor, medicine, Influenza Research Center, Baylor College of Medicine, Houston; Marc Siegel, M.D., clinical associate professor, medicine, New York University School of Medicine, New York City; May 22, 2006, Archives of Internal Medicine
Consumer News