As U.S. health authorities told Congress on Wednesday that they were prepared to mass produce a vaccine against the new H1N1 influenza virus if needed, World Health Organization officials said they would convene an expert committee next week to determine if such production was necessary -- or desirable. The U.S. is expected to follow the recommendation.
Production of a vaccine against the virus in anticipation of its return in the fall might sound like an obvious step, but doing so would sharply limit the amount of seasonal flu vaccine that would be available because the new vaccine would be manufactured instead of the traditional one.
For The Record
Los Angeles Times Saturday, May 09, 2009 Home Edition Main News Part A Page 4 National Desk 1 inches; 49 words Type of Material: Correction
Flu vaccine: The subheadline on an article in Thursday's Section A about the potential for an H1N1 vaccine said: "The downside is that such an effort would sharply limit the production of a seasonal flu antibody." It should have said -- as the article did -- "vaccine," not "antibody."
The virulence of the new strain remains unclear, but seasonal flu is a known killer. About 36,000 people die from it in the U.S. each year and tens of thousands more worldwide.
"We would not want to have no seasonal influenza vaccine," said Dr. Marie-Paule Kieny, director of the WHO Initiative for Vaccine Research, at a Geneva news conference.
She said the 20 influenza vaccine manufacturers worldwide had an annual production capacity of about 900 million doses of seasonal flu vaccine, and that might be stretched to as many as 2 billion doses of H1N1 vaccine. But that would mean abandoning the production of seasonal vaccines in plants that switched to the new vaccine.
She also said many questions remained about the production of an H1N1 vaccine, including how fast the virus would grow in the eggs used as a production medium, what size dose would be required and whether one dose would suffice.
Because the new virus is so different from circulating strains, and the general public has had no previous exposure to it, many experts think a booster shot will be necessary in addition to the vaccination. Such a booster is not needed with the traditional vaccine because of residual immunity from previous years.
If it becomes necessary to give two doses, that will sharply reduce the number of people who can be immunized.
Dr. Anne Schuchat of the Centers for Disease Control and Prevention told Congress that researchers had carried out the preliminary phase of vaccine production more rapidly than expected, and "should we need to manufacture a vaccine, we can work toward that goal very quickly."
As of Wednesday afternoon, more than 2,000 cases of H1N1 infection had been confirmed globally, with Sweden and Poland becoming the most recent countries reporting a case, bringing the tally to 24 nations.
