Creating a Model Program for Influenza Surveillance in California: Results from the 2005–2006 Influenza Season
Background
Influenza surveillance is valuable for monitoring trends in influenza-related morbidity and mortality. Using the 2005–2006 influenza season as an example, this paper describes a comprehensive influenza surveillance program used by the California Department of Public Health (CDPH).
Methods
Data collected from patients evaluated for acute respiratory illness in a given week were reported and summarized the following week, including (1) electronic hospital pneumonia and influenza admission and antiviral usage records from Kaiser Permanente, (2) sentinel provider influenza-like illness (ILI) reports, (3) severe pediatric influenza case reports (e.g., children either hospitalized in intensive care or expired), (4) school clinic ILI evaluations, and (5) positive influenza test results from a network of academic, hospital, commercial, and public health laboratories and the state CDPH Viral and Rickettsial Disease Laboratory.
Results
Influenza activity in California in the 2005–2006 season was moderate in severity; all clinical and laboratory markers rose and fell consistently. Extensive laboratory characterization identified the predominant circulating virus strain as A/California/7/2004(H3N2), which was a component of the 2005–2006 influenza vaccine; 96% of samples tested showed adamantane resistance.
Conclusions
By using multiple, complementary surveillance methods coupled with a strong laboratory component, the CDPH has developed a simple, flexible, stable, and widely accepted influenza surveillance system that can monitor trends in statewide influenza activity, ascertain the correlation between circulating strains with vaccine strains, and assist with detection of new strain variants. The methods described can serve as a model for influenza surveillance in other states.
aCalifornia Department of Public Health, Richmond, California
bCounty of Orange Health Care Agency, Santa Ana, California
cKaiser Permanente Northern California, Oakland, California
dKaiser Permanente Southern California, Pasadena, California
Address correspondence and reprint requests to: Janice K. Louie, MD, MPH, California Department of Health Services, Viral and Rickettsial Disease Laboratory, 850 Marina Bay Parkway, Richmond CA 94804.
ABSTRACT