Swine flu no longer a threat to Americans: Report

By Dr. Ananya Mandal, MDSep 29 2010

According to the latest research most Americans are immune to the swine flu virus. Results of the study by the National Institute of Allergy and Infectious Diseases, published in the journal mBio show that around 59 percent of the 310 million U.S. population has developed immunity to H1N1 either from exposure to similar viruses, vaccination, or natural H1N1 infection.

The numbers are likely to rise as people receive this year's flu shot, which protects against three strains of flu, including H1N1 say experts. About 62 million people have been vaccinated against the H1N1 virus, and 61 million have been infected, according to the study. Another 60 million people ages 57 or older are immune to swine flu because they carry protective antibodies.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), an author of the analysis said, “It's very unlikely that the virus will explode in the fall…We now have evidence of that.” Co-author David Morens, a virologist and historian also at NIAID however warns that the virus has not weakened. He said, “Even with the majority of people in the U.S. immune to the virus, that leaves many tens of millions of people still susceptible…We know the age groups that are most susceptible - people younger than 55, and those with chronic conditions.”

At present the Centers for Disease Control and Prevention (CDC) recommends vaccination for everyone 6 months and older and not just the medically at risk, says Henry Bernstein, a professor of pediatrics at Dartmouth Medical School and a member of the American Academy of Pediatrics' infectious diseases committee. High risk is considered in children, those 65 and over, pregnant women, and anyone with an underlying condition that weakens the immune system, such as HIV, asthma, diabetes, or cancer. Most people only need one shot. Children ages 6 months to 9 years may need two doses four weeks apart, if they have never been vaccinated against flu, or if they only received one dose of the H1N1 vaccine last year. Deborah Wexler, a family physician who founded the Immunization Action Coalition, an advocacy group that works to increase immunization rates explains that the first dose primes the immune system, while the second provides immune protection in children.

Five manufacturers are now making 150 million doses of a seasonal flu vaccine that includes the pandemic H1N1 virus. Norman Edelman, a pulmonologist at the State University of New York at Stony Brook and president of the American Lung Association revealed that a more potent vaccine is now available for older people. He explained that his organization has launched its 5th annual “Faces of Influenza” campaign to demonstrate how severe the illness can be. He concluded with, “Everyone can benefit from a flu shot.”