Even with the government reducing its estimates for upcoming vaccine supplies and some researchers predicting that pandemic H1N1 influenza infections are peaking this week, federal health authorities have been emphasizing the unpredictability of flu viruses in general.
If their warning about the danger of a second, larger wave of infections after the first of the year proves true, even a delayed vaccine could have an effect.
The U.S. is expected to have about 50 million doses of vaccine available by the middle of next month and 150 million by year’s end, said Dr. Nicole Lurie, the Health and Human Services assistant secretary for preparedness and response. Officials had expected to receive about 20 million doses per week beginning this month.
The problem is that the virus does not grow in eggs as rapidly as the seasonal flu virus does, thereby limiting the amount of protein that is available for inclusion in a vaccine. Lurie said that despite repeated inquiries, the companies did not tell the government about the delay until about Columbus Day.
Meanwhile, concern is growing that the vaccine may arrive too late to do much good.
Statistician Sherry Towers and Zhilan Feng of Purdue University reported last week in the journal Eurosurveillance that a mathematical model of the swine flu pandemic predicts the disease will peak this week.
But officials from the Centers for Disease Control and Prevention have emphasized repeatedly that trying to predict what any form of flu will do in the future will most likely be an exercise in futility.
“We may see in any particular community illness going down in the next several weeks, but we don’t know whether it is going to go up again,” Dr. Anne Schuchat, director of the CDC’s National Center for Immunization and Respiratory Disease, said Tuesday.
Moreover, CDC researchers have been studying the 1957 Asian flu pandemic to understand the current pandemic better, she said.
In that case, there was an early wave of the disease about September and October, “like what we are seeing here. They had another big wave after the first of the year. And so I think that as vaccine becomes available,” it is important to vaccinate as many people as possible.
Schuchat and other officials also have emphasized repeatedly that only 5% to 10% of the American public has contracted the virus. That leaves the vast majority of the public still at risk and needing vaccination.
Influenza-like illnesses, presumed to be mostly H1N1 influenza, continued to increase on college campuses last week, according to data from the American College Health Assn. There were 7,099 new cases reported among college populations totaling nearly 3.4 million students, a 9% increase from the previous week.
That makes the total for the academic year 47,000 cases. There were also 13 hospitalizations among college students last week, bringing the seasonal total to 78. No deaths have been reported.
In other flu news:
* Canada said it had approved the swine flu vaccine produced by GlaxoSmithKline and that vaccinations would begin next week.
The nation has distributed 2 million doses of the vaccine and expects to purchase a total of 50.4 million doses, enough for its population. But vaccinations could not begin until the vaccine was formally approved.
The pandemic has so far killed 83 people in Canada and hospitalized more than 1,500.
* The PBS television series “Sid the Science Kid” will air a special episode Monday that explores the science behind influenza vaccination. Health and Human Services Secretary Kathleen Sebelius and Washington schoolchildren watched the show Wednesday.
“In this special episode, Sid explains how vaccines work and shows millions of children what they can do to prevent the spread of flu,” she said.
Other flu-related activities are online at the series’ website, www.pbskids.org/sid.