NEW YORK, May 13 (Reuters Health) -- The vaccine developed for the 1998-99 flu season was well matched to the strains of flu virus that circulated in the US, according to a report released Thursday from the Centers for Disease Control and Prevention (CDC).
The flu season began in October, peaked in February and is expected to wind down this month. But CDC officials warn physicians to stay alert for cases of flu over the summer, especially in travelers returning from the tropics or Southern Hemisphere where flu activity levels may remain high.
For the third season in a row flu virus type A(H3N2) predominated in the US, and in other countries including France, Germany, the UK, Sweden, Japan, China and Russia.
Influenza B flu strains also circulated in the US, and predominated in Poland, Spain, and Taiwan.
An average of 20,000 flu deaths occur each year in the US, although during a year where type A(H3N2) predominates, as many as 30,000 to 40,000 individuals can die from the flu. Exact flu death figures for the 1998-99 season will not be available for several years, according to Dr. Carolyn Bridges of the CDC.
"I hope that people really get the message that influenza is not a cold. It is much more severe. Twenty thousand deaths in an average year is a lot of people. Most of the deaths are in older people 65 years and older, but we hear about deaths in younger people too," Bridges said in an interview with Reuters Health.
"Healthcare worker vaccination rates are very low, unacceptably low," Bridges said. "The vaccination rates of children with asthma are also very low -- much lower than we would want them to be. Children with asthma are at increased risk of complications from the flu," she added.
The 1999-2000 vaccine will offer protection against flu strains A/Sydney/5/97, A/Beijing/262/95 and B/Beijing/184/93, and will resemble the 1998-99 vaccine, according to the report. The flu strains to be included in the annual vaccine are usually selected in the early part of the year to allow for production, distribution, and administration of the vaccine.
No vaccine has yet been created for the avian flu, a new type A flu virus found in two children in Hong Kong. But "several laboratories are working to develop a candidate vaccine should the need arise," according to the CDC report. Researchers note that the presence of this strain in humans "underscores the need for continued international virologic surveillance for influenza."
SOURCE: Morbidity and Mortality Weekly Report 1999;48:374-378.
