As H1N1 sweeps US, officials brace for vaccine launch

Sep 25, 2009 (CIDRAP News) – The pandemic H1N1 virus is spreading widely through the United States, and as health officials feverishly prepare to distribute the first vaccine doses due to arrive in early October, the public should expect some initial bumps in the road, the US Centers for Disease Control and Prevention (CDC) said today.

Tom Frieden, MD, the CDC's director, told reporters at a press briefing that as health officials and manufacturers race to get the vaccine out in time to slow the quickly speading flu, which has been fueled by students' return to school, the public should brace itself for a few initial problems with the rollout. The CDC has been predicting that about 45 million to 50 million doses of vaccine will become available in mid October, followed by about 20 million a week after that, reaching a total of 195 million in December.

"It's going to be a busy and challenging next couple weeks," Frieden warned.

Five more states report widespread flu
The CDC's newest influenza surveillance report, released today, shows that flu activity is widespread in 26 states, five more than the previous week. Most states reporting widespread activity are in the southern half of the country, though Alaska, Washington, Minnesota, Illinois, and Pennsylvania are in the widespread category. Eleven states reported regional activity, and 12 states, the District of Columbia, and Puerto Rico reported local activity.

Frieden said the good news is that officials see no change in the genetic makeup of the virus or in the pattern of pandemic H1N1 infections, which is still a moderate illness that affects mainly children and young adults ages 5 to 24.

"Having the flu is no picnic, though. It can knock you right on your back for a couple of days," Frieden said, and it can cause severe illness and death in some patients.

As federal officials watch flu activity increase across the nation, they're not sure if the season will peak early and then decline for the rest of the fall or winter or if seasonal flu viruses will circulate at their normal time, he said. Today's surveillance report says 99% of circulating flu viruses in the United States are the pandemic H1N1 strain.

The percentage of doctor visits for flu-like illnesses rose for the fifth week in a row, remaining well above the national baseline. The percentage of deaths from pneumonia and flu stayed above the seasonal baseline but was below the epidemic threshold.

Three more pediatric deaths linked to the pandemic H1N1 virus were reported, two from Texas and one from Virginia.

One more case of oseltamivir-resistant pandemic H1N1 was reported, raising the nation's total to 11.

Pandemic vaccine debut nears
Frieden said the earliest doses of the pandemic H1N1 vaccine will arrive at providers' offices as early as October 6. He said the first shipments will likely be the nasal-spray FluMist version of the vaccine, because the vaccine virus grew better and the manufacturer was able to make more of it early, compared to other manufacturers.. The live attenuated vaccine from MedImmune is indicated for children and adults aged 2 through 49.

Though the CDC has advised that those with underlying health conditions should be among the first to receive H1N1 vaccine, the nasal-spray vaccine is contraindicated for most high-risk patients. However, school-age children are a priority group, and health officials have said they believe the MedImmune vaccine will be a good fit with what they hope will be widely available school-based vaccination sites.

A Sep 23 report in the New England Journal of Medicine suggested that FluMist seasonal vaccine was less effective than the injectable version in adults, which might cast doubt on how effective the pandemic H1N1 version of FluMist will be. Frieden said that though the study was carefully done, it covered only one flu season and one formulation of FluMist. He noted that other studies have shown that FluMist is more potent in kids than its injectable counterpart.

Health experts can't predict how the nasal-spray and injectable pandemic H1N1 vaccines will measure up against each other, but Frieden said he expects both will provide strong protection because the viruses in them appear to closely match the circulating strain.

During the first couple of weeks, the demand for the vaccine may exceed the supply and lead to some frustrations, Frieden said. Also, states are handling distribution to counties and cities, and they vary in their resources and expertise for managing their vaccine supplies. He added that federal health officials have allocated $1.5 billion to assist states with immunization planning and administration activities.

"In the coming weeks there is going to be some roughness," he said." We don't know what uptake will be, and we also don't know which states will have problems—but we're working hard to identify them and help them overcome difficulties." Frieden projected that the vaccine will be administered at 90,000 sites across the nation.

Frieden said providers are being urged to use the supplies they have as soon as they get them, because supplies will quickly be replenished and will become plentiful for anyone who wants the vaccine by mid to late October.

Canadian findings reverberate in US
Frieden fielded questions about a news report from the Canadian Press that revealed unpublished evidence from two respected flu researchers, who examined data from British Columbia, Quebec, and Ontario, suggesting that those who received a seasonal flu shot last year had a higher risk of H1N1 infection.

The findings have prompted some Canadian public health officials to consider delaying, reducing, or canceling seasonal flu vaccination campaigns this fall. Yesterday Ontario's chief medical officer announced that the provincial health department would postpone most of its seasonal flu shot campaign until after the pandemic vaccine has been given, the Canadian Press reported. Seniors, who are at greatest risk for seasonal flu, are still slated to receive their seasonal shots in October.

CDC officials have looked at their data and have not found that people who received the seasonal flu shot last year had a higher risk of pandemic H1N1 infection, Frieden said. He added that didn't find any evidence to confirm the link in data from New York City, where he recently served as health commissioner.

Frieden said he couldn’t imagine what mechanism would make patients who received seasonal flu vaccine more vulnerable to the pandemic H1N1 virus, though he said the CDC is taking the concerns very seriously. "If data is published, we'd love to see it, but nothing we've seen indicates that's likely to be a problem," he said.

See also:

CDC weekly influenza surveillance report

Sep 24 CIDRAP News story "Unpublished Canadian data on seasonal flu shots and H1N1 stir concern"

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