The clinical features of SARS-CoV-2 infection are becoming milder with limited symptomatic effects

The novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) and the associated coronavirus disease 2019 (COVID-19) continue to spread globally, with over 265 million confirmed cases. As of now, 55.2% of the world population has received at least one dose of a COVID-19 vaccine, with 8.24 billion doses administered worldwide and 33.99 million doses administered daily. Despite the vaccination efforts, new COVID-19 cases continue to rise, particularly in Europe. In Italy, as of January 2022, 197,000 COVID-19-positive cases were detected. From December 1, 2021, to January 8, 2022, 16,030 nasopharyngeal swab tests were processed at Altamedica laboratory using real-time RT-PCR analysis, resulting in 2,526 (15.7%) COVID-19 positive cases. Among these, 2,071 (82%) were vaccinated, and 455 (18%) were unvaccinated. Specifically, 1,739 (84%) vaccinated individuals had received 1 or 2 doses, while 332 (16%) had received a booster dose. Among the vaccinated positive cases, 1,387 (67%) were asymptomatic, 590 (28.5%) were paucisymptomatic, and 93 (4.5%) were symptomatic with fever >38°C or other symptoms; no hospitalizations occurred. Among the unvaccinated positive cases, 32 (7%) were symptomatic with fever >38°C or other symptoms, with no hospitalizations reported. To characterize SARS-CoV-2 variants, we genotyped positive samples using qPCR analysis with TaqMan probes, distinguishing between the alpha, beta, gamma, delta, and omicron variants from the A.1 (Wuhan) lineage. Our findings indicate a shift towards milder, flu-like disease severity in both vaccinated and non-vaccinated individuals, with a higher number of cases among the vaccinated due to their larger population. Additionally, our internal survey revealed a higher frequency of omicron variants compared to the national data reported by the National Institute of Health until December 9.