U-shaped-aggressiveness of SARS-CoV-2: Period between onset of nonspecific-specific symptoms for COVID-19. A population-based cohort study

Abstract BackgroundEarly identification of different COVID-19 clinical presentations may depict distinct pathophysiological mechanisms and guide management strategies. ObjectiveTo determine the aggressiveness of SARS-CoV-2 using symptom progression in COVID-19 patients. DesignHistoric cohort study of Mexican patients. Data from January-April 2020 were provided by the Health Ministry. SettingPopulation-based. Patients registered in the Epidemiologic Surveillance System in Mexico. ParticipantsSubjects who sought medical attention for suspicion of COVID-19. All patients were subjected to RT-PCR testing for SARS-CoV-2. MeasurementsWe measured the period between onset of nonspecific to specific symptoms for COVID-19 (PONSS) and compared it to the primary outcomes (mortality and pneumonia). Results65,500 patients were included. Reported fatalities and pneumonia were 2176 (3.32%), and 11568 (17.66%), respectively. According to the PONSS, patients were distributed as follows: 14.89% in <24 hours, 43.25% between 1-3 days, 31.87% between 4-7 days and 9.97% >7 days. The distribution for mortality and pneumonia was 5.2% and 22.5% in <24 hours, 2.5% and 14% between 1-3 days, 3.6% and 19.5% between 4-7 days, 4.1% and 20.6% >7 days, respectively (p<0.001). Adjusted-risk of mortality was (OR [95% CI], p-value): <24 hours= 1.75 [1.55-1.98], p<0.001; 1-3 days= 1 (reference value); 4-7 days= 1.53 [1.37-1.70], p<0.001; >7 days= 1.67 [1.44-1.94], p<0.001. For pneumonia: <24 hours= 1.49 [1.39-1.58], p<0.001; 1-3 days= 1; 4-7 days= 1.48 [1.41-1.56], p<0.001; >7 days= 1.57 [1.46-1.69], p<0.001. LimitationsUsing a database fed by large numbers of people carries the risk of data inaccuracy. However, this imprecision is expected to be random and data are consistent with previous studies. ConclusionThe PONSS shows a U-shaped SARS-CoV-2 aggressiveness pattern. Further studies are needed to corroborate the time-related pathophysiology behind these findings.