Table 2. Categorisation of seasonality methods included in the systematic review and their definition of the start and end of the respiratory syncytial virus (RSV) season, 2016−2021 (n = 32 articles).
| Data requirement | Timing | Name | Start | End | Source |
|---|---|---|---|---|---|
| Denominator | Real-time (potential) | I: % positivity threshold | 1st or 1st of 2 consecutive weeks when positivity exceeds threshold (thresholds used; 3,5, 7 or 10%) | Last or last of 2 consecutive weeks with positivity above threshold | [13,22,23,27,40,44,47,48,52,54,55,57,62] |
| II: MEM | 1st week when curve exceeds the epidemic threshold (based on historical surveillance data) | 1st week when curve is below the post-epidemic threshold (based on historical surveillance data) | [12,13,43] | ||
| Retrospective | III: mean positivity threshold | Various (e.g. 1st of 3 consecutive weeks or 1st week with percentage positive exceeding mean positivity threshold) | Various (e.g. 3rd of 3 consecutive weeks that occur at least 5 weeks following season onset, where the percentage positive is below the mean positivity threshold) | [26,51,59] | |
| Numerator | Real-time (potential) | IV: Number of detections threshold | Various (e.g. 1st week with at least 20 detections, 3 consecutive weeks with at least 6 RSV hospitalisations per week, RS10, 10-fold baseline) | Various (e.g. last week with at least 20 detections or 3 weeks with 6 or more RSV hospitalisations consecutively) | [12,20,22,58] |
| II: MEM | 1st week when curve exceeds the epidemic threshold (based on historical surveillance data) | 1st week when curve is below the post-epidemic threshold (based on historical surveillance data) | [12,13,43] | ||
| V: change point analysis | No formal definition, modelled via change point analysis | No formal definition, modelled via change point analysis | [56] | ||
| Retrospective | VI: % of detections threshold | Various (e.g. 1st week RSV detections exceed 1.2% of total RSV positive specimens) | Various (e.g. last week RSV detections exceed 1.2% of total RSV positive specimens) | [12,13,25,50,53,58] | |
| VII: mean detections threshold | Various (e.g. above the average weekly number of cases, 60% threshold) | Various (e.g. below the average weekly number of cases, 60% threshold) | [13,45,60,61] | ||
| VIII: AAP | 1st month of the longest period of consecutive months to be included in the sorted AAP 75% | Last month of the longest period of consecutive months to be included in the sorted AAP 75% | [1] |
AAP: average annual percentage. MEM: moving epidemic method. RSV: respiratory syncytial virus; RS10: retrospective slope 10.