Science in the Triangle

The H1N1 virus that fueled the 2009/2010 flu pandemic was less deadly than initially feared, but it carried enough punch to infect more than 1.4 million and kill about 25,000 worldwide.

Dr. Anne Schuchat

Also, five months after the World Health Organization declared the end of the pandemic, the virus lives on as part of the seasonal flu. In the United Kingdom, the season geared up with an outbreak caused by the H1N1 virus that emerged in 2009.

With the flu season upon the U.S., Duke University invited Dr. Anne Schuchat, U.S. assistant surgeon general, to talk about influenza preparedness at its winter forum. The two-day forum starts at the beginning of the semester and allows about 100 undergraduate students to work through a global issue and what people can do about it.

Schuchat, who kicked off the forum Sunday, spoke about the intense media attention during the pandemic and how vital information sharing and transparency was in the public health response. Her talk inspired these questions and answers to test your flu preparedness.

“Everything is called the flu these days,” Schuchat said. But a cold is not the flu.

Question: What’s the difference?

Answer: The symptoms of a cold and the flu can be similar - sore throat, cough, runny or stuffy nose - but the viruses at work are different. A cold can be caused by a human coronavirus, a rhinovirus, an adenovirus and other viruses. The seasonal flu is caused by an influenza virus, such as H1N1, H3N2 or influenza virus B. A flu can worsen existing chronic conditions such as asthma and can be followed by pneumonia, dehydration and respiratory failure.

Question: How deadly is the flu?

Answer: U.S. public health officials estimated that the seasonal flu killed as few as 3,400 and as many as 49,000 per year from 1976 to 2007, according to a report the Centers for Disease Control and Prevention published last year. That compares to about 43,000 Americans who die in auto accidents per year.

The flu viruses can change from season to season, Schuchat said. Usually, these changes are minor. Sometimes, the changes are significant and an influenza A virus appears that causes serious illness in humans. The H1N1 virus that was first confirmed in April 2009 in a 10-year-old southern California boy had undergone such a significant shift.

Question: How was the virus different from the seasonal flu virus?

Answer: Wild birds are natural hosts for influenza A viruses, but pigs can also catch the flu. The H1N1 virus that caused the 2009 pandemic was created by bird, swine and human hosts. The genetic mix created a new strain to which humans had no immunity. During the pandemic, about 61 million Americans were infected by the new H1N1 strain and about 12,500 died, according to CDC estimates. Nearly 90 percent of the deaths were adults younger than 65 and children.

Question: Can pets catch the flu?

Answer: Yes, Schuchat said. Greyhounds are susceptible. Also, the H1N1 virus was confirmed in a Bengal tiger - not that tigers make good pets, but their cousins, the domestic cats, do.

Five vaccines to protect against the H1N1 flu were developed within months, according to a response history compiled by the CDC. Four of them received regulatory approval in September and a national vaccination campaign started in October. A fifth vaccine was approved in November.

Question: How many Americans got vaccinated?

Answer: More than 80 million, Schuchat said.