Swine Flu Widespread in U.S., Vaccine Delays Continue

That's comparable to the number of flu cases at the peak of an ordinary flu season, which usually occurs between late November and early March, Frieden said. There may be more waves of flu to come this year, he added.

"We expect that influenza will occur in waves and we can't predict how high, how far or how long the wave will go or when the next will come," he told reporters.

Listen to the full news conference:

In a separate statement, the World Health Organization said Friday that there have been 414,000 laboratory-confirmed cases of H1N1 flu worldwide, and nearly 5,000 confirmed deaths. However, that number is likely underreported, the WHO said, as all countries keep their own swine flu records and some have stopped counting individual cases.

The H1N1 flu is unusual, in that it hits the young more often than the elderly. However, Frieden said that media reports earlier this week that the H1N1 flu hit one out of every five children in early October were "misinterpreted." Instead, what the study -- a telephone survey of 14,000 people -- found was that one out of every five children had some flu-like symptoms during the first week and a half of October.

"The data simply show that kids get a lot of infections," he said.

However, some communities could see one in five people affected by the flu at its peak activity, he said.

Frieden also discussed the H1N1 vaccine shortages that have led to long lines at clinics, hospitals and health centers around the country. He said that vaccine production has been slower than expected, and that the government is not likely to meet its target production of 195 million doses by the end of the year.

Officials had expected to have 40 million doses by the end of October, they've now cut that to less than 30 million. Right now, there are 16.1 million doses available, 11.3 million of which have already been shipped to doctors and clinics.

"Antiquated" vaccine production technologies are to blame for the delay, Frieden said. He said that research on new vaccine production methods is a high priority, and the Department of Health and Human Services has spent more than $2 billion on research.

"We're nowhere near where we thought we'd be [on vaccine production]," he said "and we share the frustration of people who've waited on line."

---- Compiled from wire reports and other media sources