... So that You may be kept informed

US: At least one million have had swine flu in US: official

By Karin Zeitvogel
27 Jun 2009 6:05 AM

WASHINGTON, June 26 AFP - At least one million people in the United States have had swine flu, or about 50 times more than the number of cases reported to health authorities, an official at the Centres for Disease Control and Prevention (CDC) says.

"We're saying that there have been at least a million cases of the new H1N1 virus so far this year in the United States," Anne Schuchat, director of the National Centre for Immunisation and Respiratory Diseases at the CDC told a news briefing on Friday.

"Reported cases are really just the tip of the iceberg," she said of the roughly 287,000 confirmed cases of (A)H1N1 flu in the United States.

About 3,000 people infected with swine flu in the United States have had to be hospitalised and 127 people are reported to have died.

The CDC arrived at its figure of one million cases based on computer models and surveys of communities known to have been hard hit by the new strain of H1N1 flu.

Through community surveys looking at flu-like illness "in areas where we know there's a lot of the strain circulating and in many of those communities, they're reporting proportions of about six per cent of community members having had an illness that's consistent with the new virus," Schuchat said.

A community survey conducted in New York City, where the CDC believes there have been half a million cases of (A)H1N1, showed 6.9 per cent of residents experienced flu-like illness during a three week period in May, Schuchat said.

"From their virologic testing, they knew that most of that influenza-like illness was based on this new H1N1 strain, and from that, they estimated that around half a million New York City residents may have been infected with this new virus... without necessarily seeking care," Schuchat said.

Although an infection rate of around six per cent is low compared with seasonal influenza, said Schuchat, "the survey in New York looked at a several-week attack rate while seasonal flu usually happens over weeks to months."

Schuchat said the actual figure of infected people in the United States was probably higher than one million and warned that swine flu might see higher infection rates than seasonal influenza.

"We believe the attack rates of this new virus, particularly in young people, may exceed the kind of attack rates we see with seasonal influenza," said Schuchat.

The highest rates of illness due to (A)H1N1 flu are in people under 25. The median age of people who have been hospitalised for (A)H1N1 flu in the United States is 19, and the median age of those who have died is 37.

Schuchat repeated a warning that the new strain of swine flu could come back in a more virulent form with the return of flu season in the autumn and urged communities to begin mapping out a vaccination campaign.

Five companies are working to develop a vaccine against (A)H1N1 flu, said Schuchat, without naming them.