In years past, the nation's attempts to prevent flu-related deaths have focused on limiting transmission of the virus through widespread vaccination programs. This year, with school starting up well before a vaccine for the pandemic H1N1 influenza virus will be available, there will be little that can slow the spread of the virus for the next few months.
But there may yet be something that can be done to reduce hospitalizations and deaths associated with the virus, commonly known as swine flu, public health authorities say.
Most of the serious consequences linked to the virus are the result of pneumonia, and an underused vaccine called Pneumovax can prevent, or at least limit, such complications in many patients. The vaccine, made by Merck & Co., stimulates the body's ability to neutralize the bacteria responsible for many cases of pneumonia, and it has the potential to prevent an estimated one-third of pneumonia deaths linked to swine flu.
"We would certainly like to see the vaccine used more extensively," said Dr. William Schaffner, chairman of the preventive medicine department at Vanderbilt University School of Medicine and president-elect of the National Foundation for Infectious Diseases. Schaffner was a member of the Centers for Disease Control and Prevention advisory committee on vaccines that in early June strongly affirmed current recommendations for who should receive the vaccine.
The normal target population for the pneumonia vaccine is a microcosm of those groups most likely to die or suffer serious complications from flu, so most experts say that eligible people should receive Pneumovax independent of its ability to affect the current pandemic.
But those recommendations have apparently slipped by largely unnoticed, Schaffner said.
U.S. sales of Pneumovax have not increased since June, according to John D. Grabenstein, senior director of Adult Vaccine Medical Affairs for Merck Vaccines and Infectious Diseases. Sales in Europe have risen, however, in response to similar recommendations by health authorities there.
"Unfortunately, I think too much emphasis has been placed on inappropriate administration of [the antiviral drug] Tamiflu, which has its own side effects and, aside from that, may create resistance," said Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York. "Most of my pulmonary patients are already getting [Pneumovax], but I am broadening my recommendation to other patients, since it is such a relatively harmless thing to do."
Further, the vaccine provides protection against pneumonia for up to 10 years, meaning one vaccination provides at least some safeguard not just this year but for future flu seasons as well.
Some physicians are more skeptical about the pneumococcal vaccine's potential to limit flu deaths.
"I think that the pneumococcal vaccine is a very important vaccine that should be taken by all for whom it is appropriate," said Dr. Aaron Glatt, president and chief executive of New Island Hospital in Bethpage, N.Y., and a spokesman for the Infectious Diseases Society of America. "Whether it could play a role in preventing complications from swine flu . . . I don't think that is known."
The problem is that there are many causes of pneumonia, an inflammation of the lungs that interferes with breathing and can be fatal. The influenza virus itself can cause pneumonia, as can many others. Or the lungs can be invaded by a bacterium such as Streptococcus pneumoniae or Staphylococcus aureus when the patient is weakened by a viral infection. Pneumovax protects against 23 strains of S. pneumoniae.
It is not yet clear what proportion of swine-flu-related pneumonia is caused by S. pneumoniae and thus could be prevented or ameliorated by immunization.
But preliminary results presented to the CDC vaccine committee in June by Dr. Matthew R. Moore, a CDC medical epidemiologist, indicated that about 40% of swine-flu-related pneumonia had an unknown cause -- and that about 30% were caused by S. pneumoniae. This suggests that at least a third of flu-related pneumonia deaths could be prevented by vaccination.
At least 70 million Americans are in groups that the CDC recommends receive the vaccine, according to Moore. That includes about 22 million people ages 2 to 64 with chronic underlying conditions, such as diabetes and heart disease; about 3.5 million with asthma; about 30 million smokers; and all people over the age of 65, about 15 million.
About two-thirds of the elderly have been vaccinated, Moore said, but fewer than a third of the other groups have.
"It's really a good idea to take it," said Dr. Peter Gross, an infectious-diseases expert at Hackensack University Medical Center in New Jersey. "I don't know why it is not pushed more."
The committee has not recommended the vaccine for pregnant women, who are about six times as likely to die from complications of swine flu as the population at large.