August 23, 1996

Vaccine targets respiratory virus in elderly

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Dr. Kathleen Neuzil

Vaccine targets respiratory virus in elderly

Vanderbilt researchers are gearing up for the annual battle against coughs and sniffles by testing a vaccine that targets the respiratory syncytial virus (RSV), one of the building blocks of the common cold.

Long studied in children, this virus is now being investigated in elderly populations, where it can lead to pneumonia and, in some cases, even death.

Beginning Aug. 28, VUMC's Adult Infectious Diseases Division will test the vaccine on healthy elderly patients to evaluate the immune response elicited by the vaccine.

"RSV is a virus that infects upper and lower respiratory tracts," said Kathleen M. Neuzil, assistant professor of Medicine and principal investigator of the study.

Most studies of RSV have involved infants and young children, in whom RSV may cause severe illness requiring hospitalization, Neuzil said. Generally, RSV infects in the winter and is transmitted from children to adults. Older children and adults may get symptoms of a bad cold from RSV.

In the elderly and other immunocompromised adults, the illness may be more severe and lead to pneumonias or exacerbations of pre-existing conditions, such as heart or lung diseases.

Neuzil said when RSV strikes, it usually starts as a cold with symptoms including nasal congestion, cough, difficulty in breathing and wheezing. It can then progress to more severe disease, such as pneumonia. Pre-existing conditions, such as lung disease or allergies, may worsen for long periods of time.

"In one study of community-dwelling elderly, of those who had RSV and went to the hospital with acute lung problems, up to 10 percent died," said Neuzil.

The shift of study from children to the elderly represents a new direction in RSV research, Neuzil said.

"Previously, nobody really looked for RSV in seniors. There is a tremendous amount of current research directed at developing a successful vaccine for RSV, particularly in young children. This is a difficult task, as this group has immature immune systems and has not been previously exposed to RSV.

"Most adults, however, have had RSV several times in their lives. A vaccine that boosts or reminds their immune systems about past infection may be sufficient to prevent spread of RSV from the nose to the lungs, where it can do the most damage."

The boost Neuzil talks about may be from the purified fusion protein (PFP-2) vaccine. This vaccine is based on the RSV fusion, or F protein, which is important for the virus to bind and initiate infection.

This vaccine has been tested in children and adults and has been well-tolerated. Vanderbilt is only the second center to test it in adults over 60.

"The vaccine can't cause infection. It's not a live virus," said Neuzil. "If we can get an immune response from the patient, the vaccine could prevent virus entry and hopefully inhibit the spread of RSV from the nose to the lungs."

The study will not contain a placebo, said Neuzil. Each subject will receive a dose of the PFP2 vaccine – either 10, 25 or 50 micrograms. She is testing for the lowest dose that will cause a significant (four-fold rise) antibody response in at least 80 percent of the subjects.

"We're looking at tolerability, or side effects. In previous studies of both healthy and frail adults, there were no adverse reactions – just an occasional sore arm from injecting the vaccine," said Neuzil.

One hundred patients are being sought for the study. Healthy adults aged 60 to 90 who participate receive $75 and free parking for making just two visits.

Neuzil said she wants to finish the study before RSV season, which usually runs from December through April, and the vaccine should help patients avoid RSV and the respiratory problems it causes.

"The next step is to find out how well it works. Lots of people will receive the vaccine, and that study will test with a placebo. Researchers will be looking to see if it increases antibody response."

Healthy adults 60 to 90 years of age who are interested in participating in the RSV study may contact Neuzil or Erlene Cammack, study nurse, at 322-2477.