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"Among the 18 fundamental points in the U.S. pandemic plan, there is little mention of bacterial vaccines. I believe their role is significant and has not been considered up until now," he said at an international conference on community-acquired pneumonia.

Although the influenza virus alone can be fatal, the risk of death is greater with secondary pneumococcal infection, said Dr. Klugman, professor of infectious diseases and the William H. Foege Chair of Global Health at Emory University, Atlanta.

"The combination of bacterial superinfection and influenza is highly fatal. It's a huge problem, and it's not a small part of influenza mortality and morbidity," he said in an interview.

Evidence that pneumococcal infection played a major role in the 1918 influenza pandemic "'is substantial, but seems to have been forgotten," Dr. Klugman recently wrote in a letter to the editor (Science 2007;316:49-50).

He cited historical evidence of culturable pneumococci in the blood of at least half of the survivors and victims of influenza in two studies (Br. Med. J. 1919; 1:3-5; JAMA 1918;71:1735).

And a randomized, controlled trial by Dr. Klugman and his colleagues has shown that, in children, vaccination against the pneumococcal bacteria results in a 31% decrease in pneumonias associated with respiratory viruses (Nat. Med. 2004; 10:811-3).

"Because of the vaccine, they are not getting the superinfection that brings them to the hospital," he said at the meeting, which was sponsored by the International Society of Chemotherapy. "I think people have known for years that there can be bacterial superinfections with influenza, but they just didn't realize how common they were and how much of a role they play."

The 23-valent pneumococcal polysaccharide vaccine (PPM 23) is currently recommended in adults older than 65 years, but giving the 7-valent pneumococcal conjugate vaccine (PCV 7) to children is more protective against bacterial pneumonia in the adult population, he said.

Data from the Centers for Disease Control and Prevention show that adult infections with the seven pneumococcal strains covered in the children's vaccine have decreased, while infections from the other 16 strains covered by the adult vaccine have increased.

"The burden of disease in adults has been impacted more by giving the conjugate vaccine to children than by giving the 23-valent vaccine to adults," Dr. Klugman said.

This has led some investigators to ask whether adults might benefit by being immunized using the children's conjugate vaccine. (See box, "Giving Adults the Children's Conjugate Vaccine May Backfire, Researchers Say".)

Also, a new study (Lancet 2007;369:1179-86) offers the first evidence that vaccinating children protects adults against all pneumococcal pneumonia, not just bacteremic pneumococcal pneumonia, he said.

Improving pneumococcal vaccine coverage in children could result in major reductions in infection across all ages, he said.

"Only about 60% of kids currently get the full four doses of the conjugate vaccine, and it's that fourth dose that induces the full immunity and stops transmission, so we need to do a much better job of immunizing kids."

REALTED ARTICLE: Giving adults the children's conjugate vaccine may backfire, researchers say.

Is there a role for giving the children's conjugate vaccine to adults?

A recent study suggested that it may not be as simple as that (Vaccine 2007;25:4029-37). Immunogenicity among elderly patients (aged 70-79 years) who were given the children's dose of conjugate vaccine was "nothing to get overly excited about," Dr. Klugman said. "Perhaps the dose designed for a primary response in kids is not enough for adults," he suggested.

And a study presented at the 2006 International Symposium on Pneumococci and Pneumococcal Diseases by Dr. Andres de Roux, of the Universitat Autonoma de Barcelona, and colleagues suggested that the administration of the children's conjugate vaccine to elderly patients within 1 year of giving them the polysaccharide vaccine could actually suppress immunity.

"It seems the adult vaccine interferes with the response to the conjugate, which is a concern, because it means we can't simply give the conjugate to people who have previously had the [23-valent vaccine]. There will have to be a strategy, and it seems that certainly the conjugate needs to be given before the 23-valent," Dr. Klugman said.

Dr. Klugman said that in his opinion, a new conjugate vaccine, with coverage of more strains than the current one, will eventually replace the PPV 23 for adults.

ARTICLES BY KATE JOHNSON