A common, flu-like childhood illness called respiratory syncytial virus infection (RSV) also affects older adults and adults with health problems.
"RSV infection is an important illness in elderly and high-risk adults," say Ann Falsey, MD, and colleagues in The New England Journal of Medicine's April 28 edition, adding that the burden from this disease is similar to that of flu infection.
"For the elderly, RSV can be serious, similar to the flu. Overall, RSV causes a substantial burden of disease in adults. Development of a vaccine would be worthwhile," continues Falsey, an associate professor of medicine at the University of Rochester in New York.
Falsey's study estimates that every year, RSV causes 14,000 deaths among elderly and high-risk people and more than 177,500 adults to be hospitalized at a cost of more than $1 billion.
RSV is the most commonly identified cause of lower respiratory tract infection in very young children, according to the study. Repeat infections with the virus can cause moderate to severe cold-like symptoms throughout life. In adults, especially the elderly and those with heart and lung disease, symptoms can resemble a longer, more severe common cold.
RSV infections are usually seen from October through April -- the same time as flu season.
Falsey and colleagues studied RSV infection for four consecutive winter seasons in Rochester, N.Y.
Participants were healthy adults aged 65 or older (608 people), "high-risk" adults over age 21 with heart failure or lung disease (540 people), or hospitalized adults (1,388 people). The average age in all groups was at least 70, the study shows.
The percentage of people with exposure to children was higher in the high-risk group than in either the healthy elderly group or the hospitalized group.
RSV, Flu Both Common
During the four winters, participants reported 2,514 cases of illness, of which RSV accounted for 244 of them.
RSV was seen in 142 hospitalized people, 46 healthy elderly patients, and 56 high-risk patients. That's 3 to 7 percent of healthy elderly patients and 4% to 10% of high-risk adults annually, says the study.
Influenza type A was seen in 154 hospitalized participants, 24 healthy adults, and 20 high-risk adults.
Healthy adults saw their doctors more often for flu, not RSV. High-risk adults made a similar number of doctors' visits for flu and RSV.
For hospitalized patients, RSV and influenza type A had similar lengths of stay, rates of intensive care, and mortality (8 percent for RSV and 7 percent for flu), says researchers.
"RSV infection accounted for 10.6 percent of hospitalizations for pneumonia, 11.4 percent for chronic obstructive pulmonary disease, 5.4 percent for congestive heart failure, and 7.2 percent for asthma," they write.
The findings were used to estimate RSV infection on a national scale. The study only included people in one city, but the estimates are in line with other studies, say the researchers.
Editorial: Vaccine Momentum Has Waned
Falsey's call for an RSV vaccine is echoed in an editorial in The New England Journal of Medicine.
The World Health Organization has put RSV on its list of high-priority pathogens for vaccine development, but enthusiasm has faded in the past decade, write Sanjay Sethi, MD, and colleagues.
Possible reasons for that include "scientific challenges, the high-risk nature of the target population, and the enormous cost of vaccine development," the editorial notes.
Lack of public awareness about RSV infection could also be a reason, write Sethi and colleagues. Sethi works in Buffalo, N.Y., in the department of medicine at the Veterans Affairs Western New York Healthcare System.
His co-author, Timothy Murphy, MD, has a licensing agreement for bacterial vaccine development with drug company Wyeth, says the journal. Murphy works in the medicine department at the University of Buffalo, State University of New York.
SOURCES: Falsey, A. The New England Journal of Medicine, April 28, 2005; vol 352: pp 1749-1759. Sethi, S. The New England Journal of Medicine, April 28, 2005; vol 352: pp 1810-1812.