EPICOVID19 protocol: repeated serological surveys on SARS-CoV-2 antibodies in Brazil. - Hallal PC; Barros FC; Silveira MF; Barros AJD; Dellagostin OA; Pellanda LC; Struchiner CJ; Burattini MN; Hartwig FP; Menezes AMB; Horta BL; Victora CG (Ciencia & saude coletiva, 2020)