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Study: H1N1 transmission rates continue decline

Category: Infectious Diseases

Recent clinical tests have revealed that people over the age of 19 may express more immunity to the H1N1 flu strain than scientists initially thought.

During a study conducted by the Centers for Disease Control and Prevention and Imperial College London, researchers tracked the spread of the flu in 216 households in which one family member had been diagnosed with the virus when it began spreading in spring 2009, HealthDay News reports.

The scientists found that only 13 percent of other members of the household came down with the flu, and children and teenagers under 18 years old were twice as likely to contract the virus as those between 19 and 50.

The study's co-author Lyn Finelli, director of the CDC's Epidemiology and Surveillance H1N1 Response Team, told the news source that adults were probably less affected by contact with the virus "because people in the middle age group have a little acquired immunity because of prior exposure to another virus that was similar enough."

According to the researchers, most transmissions of H1N1 occurred either shortly before or after the first infected person began showing symptoms.

The CDC reports that last week, seven states reported widespread influenza activity - down from 11 the previous week and 48 states in October.