COVID-19 epidemiological waves cannot be predicted with SARS-CoV-2 viral load

Background: SARS-CoV-2 infection has caused more than 6.6 million deaths worldwide, and its transmission model has been questioned. The viral load of the virus was probably the main driver of the transmission of COVID-19. Therefore, this study assessed the impact of the viral load of SARS-CoV-2 on the epidemiological wave of COVID-19. Methods: Samples for COVID-19 were analyzed using RT-qPCR at the Molecular Biology Laboratory of the Hospital Santa Casa de Misericórdia de Porto Alegre. Epidemiological data were drawn from prefectural and state websites. Wavelet analyses with a 3-days filter were used. Results: A total of 11.302 positive COVID-19 samples from patients residing in Porto Alegre were evaluated; most patients were female, and the mean age was 44.6 years-old. The median relative viral load (RVL) median was 9.98 copies/mL. Conclusions: The relative viral load could not predict the waves of COVID-19, due to the virus mutation. There were periods of high RVL where transmission occurred within 32 days and periods of low RVL where transmission occurred up to 16 days.