The New York State Sentinel Provider Network, 2007-2008
The New York State Sentinel Provider Network continues to provide valuable clinical and virologic information for state, national and global influenza surveillance. Since its inception in 1998, the network has grown from seven to 125 sentinels, now reporting on over 83,000 patient visits per week during the influenza season.
New York sentinel providers are part of a 2,500-member, nationwide influenza surveillance network sponsored by the Centers for Disease Control and Prevention (CDC). Because influenza is not a reportable disease in most states, the CDC seeks patient specimens from volunteering healthcare providers and weekly reports of influenza-like illness (ILI). ILI is defined by CDC as fever ≥100°F and cough or sore throat in the absence of a known cause other than influenza. This information — combined with influenza surveillance data from hospitals, nursing homes and collaborating laboratories — is used to monitor the timing, location, and impact of influenza viruses from October through May and, increasingly, throughout the entire year. The geographic distribution of 2007-08 New York sentinel surveillance sites is mapped in Figure 1.
Figure 1
- The New York State Sentinel Surveillance Sites Map is also available in Portable Document Format (PDF, 36KB, 1pg)
Influenza Reporting
New York State (NYS) sentinels, including sentinels located in New York City (NYC), reported on almost 3 million patient visits (over 300,000 outside of NYC) during the 2007-08 influenza season (beginning this season, NYC included syndromic surveillance of emergency department visits in its sentinel surveillance system). Approximately 2.3 percent (close to 64,000) of those patients were diagnosed with influenza-like illness. Weekly percentages of office visits for ILI ranged from 1.2% to 4.4% in the state. The peak percentage of ILI of 4.4% was reached during the week ending February 16, 2008. In the Mid-Atlantic Region, which includes New York State, office visits for ILI in excess of 3.1% correlate with annual epidemic influenza activity; this level was exceeded 7 out of 33 surveillance weeks (21%). The 2007-08 influenza season was characterized by the CDC as moderately severe, with national influenza activity increasing sharply at the end of January, and peaking in mid-February. Approximately 37% of the patients diagnosed with ILI were in the 0-4 year age group; 33% were in the 5-24 year age range; 26% were in the 25-64 year age group; and 4% were in the >65 year age group.
For each of the past eight seasons, NYS sentinel surveillance has matched the onset, peak and duration of influenza activity identified in data from the state's healthcare facilities and World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories.
The temporal distribution of influenza activity for the 2007-08 influenza reporting season, October 6, 2007 – May 17, 2008, as defined by all three surveillance systems, is presented in Figure 2.
Figure 2
Specimen Collection
In 2007-08, 125 New York City and Upstate sentinels submitted 121 respiratory specimens, 118 of which were testable, to the New York State Department of Health (NYSDOH) Wadsworth Laboratories. Sixty-eight percent (80) of specimens submitted by sentinels tested positive for influenza. Seventy-nine percent (63) of these specimens were positive for influenza A. Forty-four of those positive for influenza A were influenza A(H3N2), 15 were influenza A(H1N1), and four were influenza A, unsubtyped. Twenty-one percent (17) of specimens were positive for influenza B. An additional five specimens were positive for other respiratory viruses: 1 adenovirus-3; 1 Coxsackie B1; 1 parainfluenza 1; and 2 parainfluenza 2.
Specimens collected at the season's onset are used to gauge the match between circulating influenza virus strains and those covered by the current vaccine. Specimens collected at the season's midpoint and end assist the CDC and WHO in determining strains for inclusion in next year's vaccine. The CDC also seeks specimens from unusually severe or outbreak-related cases of influenza, as part of its continuing surveillance for novel influenza subtypes which could lead to the next influenza pandemic.
Feedback
Providers using the CDC Internet Reporting System can easily link to regional and national influenza updates. Weekly updates for New York State can be accessed on the Department of Health's Web site . Participants also receive complimentary annual subscriptions to the CDC journals Emerging Infectious Diseases and Morbidity and Mortality Weekly Report. Participation in the sentinel provider influenza surveillance network satisfies family practice residency research requirements.
Healthcare Providers Supply Critical Public Health Data
Influenza viruses are constantly evolving and cause substantial morbidity and mortality annually. The data sentinel providers collect, in combination with other surveillance data, are used to guide influenza prevention and control activities.
The CDC seeks one healthcare provider to represent each 250,000 residents. Sentinels are needed in all parts of the state. Specific areas of need in which providers are under-represented as a group among sentinels include:
- sentinels in the major metropolitan areas
- providers who specialize in geriatrics or whose patients are mainly in the > 65 year age range.
Physicians, physician assistants, nurse practitioners, and nurses from any specialty and any practice type are invited to enroll. Sentinels report the number of patients seen with ILI in four broad age categories, and the total number of patients seen each week. Reports are submitted to the CDC via the Internet or fax. The entire process is estimated to take 15 to 30 minutes each week. Materials to collect and ship six patient specimens per season to the New York State Department of Health virology laboratory are provided without cost. PCR testing, culture, typing and sub typing are performed by the laboratory at no cost to the provider or patient.
Contact Information
Upstate providers, please contact Christine Waters (518-473-4439, clw06@health.state.ny.us), Program Coordinator at the New York State Department of Health to receive more information or to volunteer to provide this valuable public health service. Providers in New York City, please contact Beth Nivin, Program Coordinator at the New York City Department of Health and Mental Hygiene (212-442-9050, bnivin@health.nyc.gov).