As the Centers for Disease Control and Prevention launches its annual Influenza Vaccination Week beginning December 5, Yale’s Emerging Infections Program (EIP) is also gearing up for another season of flu surveillance.
Locally, the EIP has monitored influenza-related hospitalizations since 2003. Currently EIP conducts surveillance in three Connecticut counties: Hartford, Middlesex and New Haven. The data is used by state health officials and the CDC to monitor the severity of the flu season, to measure the effectiveness of each year’s vaccine and to identify complications from the virus.
This year’s flu vaccine is designed to protect against an influenza A virus (known as H3N2), an influenza B virus and the H1N1 virus that caused widespread illness—particularly among children—last season. Compared with the previous influenza seasons, 2009-10 saw a 67 percent relative increase in vaccine rates for children and a 30 percent relative increase for adults despite early shortages of the vaccine.
“Each flu season is unique and it’s nearly impossible to predict how severe it will be this year,” says James Meek, associate director the EIP, a research group within the School of Public Health. “However, we can say that CDC has characterized 13 influenza viruses from across the United States since October 2010 and all of these were closely related to the three strains included in this year’s seasonal influenza vaccine.”
Each year in the United States between 5 percent and 20 percent of the population on average is infected with the flu, and more than 200,000 people nationwide may be hospitalized.
Nationwide, minority groups had consistently higher rates of serious H1N1 disease last year, including hospitalizations, than non-minority groups. American Indians and natives of Alaska were hospitalized more than any other group, followed by Hispanics and black/non-Hispanics. Recent EIP hospitalization data showed that the majority of people hospitalized from the 2009 H1N1 flu had at least one underlying health condition such as asthma, diabetes or cardiovascular disease.
The EIP is a joint effort of the Yale School of Public Health and the Connecticut Department of Public Health and is funded by CDC. EIP activities at Yale are directed by Robert Heimer, a professor at the Yale School of Public Health. The program seeks to assess the public health impact of emerging and re-emerging infections and to evaluate methods for their prevention and control. As one of 10 national EIP sites, it also monitors and studies other diseases, including foodborne diseases, Guillain-Barre Syndrome, human papillomavirus and tick-borne diseases.