TABLE 2.
Surveillance evolution criteria and associated subcriteria (primary care surveillance subsystem example)
| Criteria | Sub‐riteria | WHO guidance a |
|---|---|---|
| Granularity | Age group | Recommended as a minimum: 0–1, 2–4, 5–14, 15–49, 50–64, 65 + years and ideally additional age strata for under 2 years including 0 to <6 months, 6 month to <1 year, 1 to <2 years |
| Gender | Where possible data should be extracted by gender | |
| Risk condition | Recommended as a minimum: pregnancy status & presence of chronic pre‐existing medical illness (es): chronic respiratory disease, asthma, diabetes, chronic cardiac disease, chronic neurological or neuromuscular disease, haematological disorders, immunodeficiency (including Human Immunodeficiency Virus) | |
| Location | Considered as essential, especially for burden estimation for a given area based on data from sentinel sites | |
| Virology | Types and subtypes of viruses detected during the week | |
| Severity | Additional data to consider: signs and symptoms of illness & patient outcome (death, survival) | |
| Treatment | Exposure to influenza antiviral drugs during the last 14 days? If yes, name of antiviral | |
| Vaccination status | Additional data to consider: Seasonal influenza vaccination status and date of administration | |
| Timing | Frequency | Epidemiological and virological data collected from the sentinel sites should be reported to the national health authorities on a weekly basis |
| Time period | In temperate climate zones where influenza seasonality is well understood, data collection and reporting should occur at a minimum during the known influenza season and for a short period preceding and following the season | |
| Representativeness | Geographical representativeness | National ‐ sentinel sites should include patients that will appropriately represent the population |
| Population representativeness | The population served by the sentinel site should be representative of the target age and socioeconomic groups in the population under surveillance | |
| Number of settings | There is no ideal number of sentinel sites in a country. Start small with one or a few sentinel sites and only expand if these function well. Minimal information that should be presented in the weekly report includes number of sentinel sites reporting | |
| Proportion of facilities | Ideally the following analyses can be presented in an annual report: data from the monitoring of the system: proportion of sentinel sites reporting weekly to the national level; and if feasible, the proportion of sentinel sites regularly submitting specimens for laboratory testing | |
| Sampling Strategy | Surveillance type | Sentinel surveillance |
| ARI/ILI definition | An acute respiratory infection with fever ≥38 °C and cough with onset within the last 10 days | |
| Sampling | A systematic approach to case selection that does not leave the choice of cases to test or gather data from up to healthcare providers (other than to determine that the case meets the definition), and that covers different times of the day and different days of the week is likely to be the most pragmatic, whilst providing reasonably representative data | |
| Test type | Reverse transcriptase‐polymerase chain reaction (RT‐PCR) is the most sensitive method for detecting influenza virus and is the recommended influenza surveillance assay for laboratories | |
| Communication | In annual report | Yearly surveillance report with surveillance and risk factor data should be produced |
| In weekly report | Weekly surveillance reports should be produced and made accessible to relevant partners | |
| Delay in release | Reports should provide timely information on influenza activity and types of influenza viruses circulating | |
| Data can be extracted | Whenever feasible, such reports should be available to the public on the national surveillance website | |
| Infographics/dashboard b | Availability of user‐friendly infographics and/or dashboard | |
| Interactive map b | Availability of a user‐friendly interactive map |
Note. Adapted from El Guerche‐Séblain et al. 13 Further information is included in the Supporting Information.
Abbreviations: ARI, acute respiratory illness; ILI, influenza‐like illness; RT‐PCR, reverse transcriptase‐polymerase chain reaction.
a
From WHO global epidemiological surveillance standards for influenza 49 and WHO manual for estimating disease burden associated with seasonal influenza. 39
b
Not included in El Guerche‐Séblain et al. 13