Epidemiological Significance of SARS-CoV-2 RNA Dynamic in Naso-Pharyngeal Swabs

Calistri, Paolo; Danzetta, Maria Luisa; Amato, Laura; Cito, Francesca; Di Giuseppe, Alessandra; Zenobio, Valentina; Morelli, Daniela; Puglia, Ilaria; Caporale, Marialuigia; Scialabba, Silvia; Savini, Giovanni; Migliorati, Giacomo; D’Alterio, Nicola; Lorusso, Alessio

From 16 March to 15 December 2020, 132,357 naso-pharyngeal/oropharyngeal swabs were collected in the province of Teramo, Abruzzo Region, Italy, and tested for the presence of SARS-CoV-2 genomic RNA by a commercially available molecular assay. A total of 12,880 swabs resulted positive. For 8212 positive patients (4.150 women and 4.062 men) the median age was statistically different between women (median: 49.55 ± 23.9 of SD) and men (median: 48.35 ± 23.5 of SD) while no differences were found in the comparison between the cycle threshold for the N protein-encoding gene (C(T) N) median values and gender. Differences were observed in the C(T) N gene median values of swabs collected from March to September as well as in the pairwise comparison between September and October and between November and December. The C(T) N gene median values observed in specific periods characterizing the SARS-CoV-2 epidemic in 2020 were also compared with the incidence of COVID-19 cases; a strong inverse correlation was highlighted (Pearson correlation coefficient = −0.978). Our findings confirm the usefulness of the C(T) N values as an indirect detection parameter to monitor viral loads in the population.