Evaluation of the acute respiratory infections surveillance system and associated factors: a cross-sectional study, Brazil, 2009-2021.

Objective: To evaluate quality of acute respiratory infection reporting in Brazil, 2009-2021, and to analyze association with contextual factors, the COVID-19 pandemic and death as the clinical outcome.

Methods: Cross-sectional study of quality of completeness and timeliness of reporting held on the Influenza Epidemiological Surveillance System, via OpenDATASUS, based on Centers for Disease Control and Prevention guidelines. Pearson's chi-square test was applied to compare sociodemographic and geographic factors, Bayesian structural time series were used to measure the impact of the COVID-19 pandemic and logistic regression was used to analyze association with the clinical outcome, using odds ratios (OR) and 95% confidence intervals (95% CI).

Results: Among the 3,401,881 reports, 53.6% had high completeness, ranging from 71.3% in the South to 37.3% in the Northeast. The surveillance stages with least timeliness were case identification (13.0%), sample collection (28.2%) and data entry (43.5%). During the COVID-19 pandemic, completeness reduced by 34.8%, mainly among sociodemographic (35.9%) and signs and symptoms (28.5%) variables. Completeness of signs and symptoms variables (OR 0.56; 95%CI 0.55; 0.56) and hospital care variables (OR 0.91; 95%CI 0.90; 0.92), as well as timely communication (OR 0.72; 95%CI 0.71; 0.72), sample collection (OR 0.90; 95%CI 0.89; 0.90) and data entry (OR 0.91; 95%CI 0.90; 0.92), was associated with lower odds of death.

Conclusion: This study demonstrated that completeness and timeliness of acute respiratory infection epidemiological surveillance actions has regional inequalities, with effects on filling out records during the COVID-19 pandemic and associations with clinical outcomes.