Abstract
BACKGROUND: In 2020, countries implemented universal surveillance to detect and monitor severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases. Although crucial for early monitoring efforts, universal surveillance is resource intensive. To understand the implications of transitioning from universal to sentinel surveillance for monitoring SARS-CoV-2 transmissibility, morbidity and mortality, and disease seriousness, we compared measures of SARS-CoV-2 reported from both surveillance strategies in Argentina, Chile, and Mexico. METHODS: We obtained weekly case counts in Argentina, Chile, and Mexico, in periods when both universal and sentinel surveillance were ongoing. To assess the countries' surveillance strategies, we measured the proportion of total sites that were included in sentinel surveillance. We compared 8 measures of SARS-CoV-2 transmissibility, morbidity and mortality, and disease seriousness between sentinel and universal surveillance and assessed the correlation between the 2 strategies for the 8 measures. Pearson and Spearman correlation was classified as very strong (rs = 0.8-1.0), strong (rs = 0.60-0.79), moderate (rs = 0.50-0.59), or poor (r < 0.50). RESULTS: The proportion of total sites included in sentinel surveillance was 5.8% for Argentina, 1.1% for Chile, and 7.6% for Mexico. A total of 21 measures were calculated (8 for Mexico, 8 for Chile, and 5 for Argentina). Of these, 17 showed consistency between the 2 surveillance strategies, with strong or very strong correlations (r = 0.66-0.99): all 8 measures for Mexico, 6 of 8 measures for Chile, and 3 of 5 measures for Argentina. Each country had ≥1 measure reflecting transmissibility and ≥1 reflecting morbidity and mortality for which the correlation was strong or very strong. Chile and Mexico also had ≥1 measure of disease seriousness for which the correlation was strong. CONCLUSIONS: Our findings suggest that the integration of SARS-CoV-2 into national sentinel surveillance can yield information comparable to that provided by nationwide universal surveillance for measures related to SARS-CoV-2 transmissibility, morbidity and mortality, and seriousness of disease.