Publication date: Jan 29, 2025
Estimate the detection limits of the COVID-19 surveillance system (SS) in Chile, by estimating the SARS-CoV-2 true prevalence (TP) and the reported official positivity prevalence (OPP) gap. Randomized cross-sectional. Two sampling campaigns (SC) were conducted (October-November 2020 and December 2020-January 2021) in the cities of Temuco, Valdivia, and Osorno. Blood was collected from adults from randomly selected households. Sera were analyzed using a commercial later flow test (LFT). A meta-analysis was performed to estimate LFT-performance in asymptomatic-cases. Data were analyzed using a Bayesian latent class model (BLCM) to estimate TP. Finally, BLCM outputs were compared with the OPP, by calculating the TP/OPP rate. 1124 and 1017 households were visited during the 1st and 2nd SC, respectively. The BLCM rendered TP estimates of 6. 5 %, 3. 2 %, and 6. 6 % for the cities of Temuco, Valdivia, and Osorno, respectively (1SC), increasing to 9. 4 %, 5. 0 %, and 7. 5 %, 60 days later (2SC). Depending on the city and SC, TP/OPP rates varied between 2. 3 and 5. 7. The national SS was unable to detect 70-79 % of all infected cases, suggesting that mild and asymptomatic cases were scarcely detected.
| Concepts | Keywords |
|---|---|
| Chile | Detection limits |
| December | SARS-CoV-2 |
| Surveillance | Surveillance |
| True prevalence |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | COVID-19 |
| disease | IDO | blood |