Evaluation of the Effectiveness of Surveillance Policies to Control the COVID-19 Pandemic in São Paulo, Brazil

Abstract

Background: Surveillance efforts are critical to pandemic control, especially where the state is the primary health provider, such as Brazil. When public health testing guidelines limit RT-PCRs, there are reductions in detection efforts aimed at early recognition, isolation, and treatment of those infected with the virus.Methods: We conducted an interrupted time series analysis with a segmented regression model using publicly available data to analyze if changes in the state’s guidelines improved RT-PCR testing outcomes in Brazil’s most affluent and largest state, São Paulo, from March 2020 to June 2021. Results: The São Paulo state’s policy guidelines have changed substantially over time. In the first months, the public health system restricted RT-PCR testing to hospitalized cases. Testing was expanded to permit symptomatic testing of non-hospitalized persons only in July 2020. In September 2020, there was a review of the national surveillance guidelines and case definition was expanded to permit case confirmation based on clinical, laboratory and image data criteria other than an RT-PCR test. In February 2021, policies were revised to instruct public health agencies to increase epidemiological monitoring with genomic data. Results show an uneven improvement in testing outcomes following these changes across the state’s regional health departments. Conclusions: Evidence suggests that lower RT-PCR testing and genomic surveillance efforts are associated with areas characterized by a higher population concentration and a greater reliance of the population on the public health system.