Vaccination for the pandemic influenza A(H1N1) virus remains critical, because it is medicine's best tool for preventing or moderating infection, officials with the Centers for Disease Control and Prevention continued to stress last month.
By mid-October, almost 10 million doses of pandemic flu vaccine were available for order and shipment to health care providers registered to provide the immunizations, Dr. Anne Schuchat, director of the CDC National Center for Immunization and Respiratory Diseases, said during a press briefing.
At that point, “5.8 million of those doses had been ordered by states, and we are getting both new orders and new allotments every day,” Dr. Schuchat said at the press briefing.
“It's a very dynamic circumstance,” she noted.
Half the vaccine was the injectable form, significantly expanding the potential pool of recipients, according to Dr. Schuchat.
The intranasal vaccine—which earlier accounted for the majority of available pandemic flu vaccine—contained live, attenuated virus, and was not recommended for those with underlying medical conditions, including asthma and other chronic lung diseases; for pregnant women; or for children younger than 2 years.
With the addition of the injectable version, “More places will have the ability to offer the vaccine to these groups, so many more can take advantage of it,” she said. “Each locality is directing the vaccine to the places where it can be given quickly to high-risk populations or to health care workers, and to children and schoolchildren in some communities. The [localities] are trying to take the doses available to them and find focused, practical ways to get them used promptly.”
While U.S. case numbers of H1N1 flu had dipped by that point, CDC Director Thomas R. Frieden stressed that the vaccine has not arrived too late.
“We wish we had [the vaccine] earlier,” conceded Dr. Frieden, but added “it's too soon to say it's too late, because we don't know what the rest of the [flu] season will bring. Even in areas where flu has been widespread, it's affected maybe 5%-10% of people, which means that 90%-95% are still susceptible.”
Dr. Frieden noted that, while flu infection has been uncharacteristically active in August and September, because of H1N1, the flu season will stretch to May.
“It's a good idea to get vaccinated, because you don't know what the rest of this long flu season is going to hold. We have not had a flu season like this for at least 50 years,” he noted.
So far, neither of the two biggest concerns about the H1N1 pandemic has materialized, Dr. Frieden said.
The virus has not become deadlier during the 6 months since it first appeared in late March, and it has not undergone any change that would make the vaccine now available less effective. More than 1,000 H1N1 isolates worldwide have been analyzed, and they show a very stable virus.
The vaccine is antigenically “right in the middle, making it an excellent immunologic fit against the circulating virus,” he said.
A high level of vaccine uptake by the public will depend on how easily available it is and on selling the public on three facts, said Dr. Frieden:
1. Flu usually is not mild. It can knock a person out for a day or 2 or 3, it can make some people require hospitalization and intensive care, and it will kill some people. “Flu can be very serious, and the average case is no picnic,” he said.
2. The best way to avoid flu is by vaccination, and the CDC has a “high degree of confidence” in the safety of the vaccine. That's because it's been made in exactly the same way as hundreds of millions of prior flu vaccine doses that were administered in the past. The CDC and vaccine manufacturers did not “cut any corners” in making the vaccine.
3. The H1N1 pandemic is unpredictable, the flu season is long, and vaccination is the best way to prevent or minimize infection, so it still makes sense for as many people as possible to get the vaccine.