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Comparative Study
. 2020 Jul 20;91(9-S):19-21.
doi: 10.23750/abm.v91i9-S.10138.

Virological surveillance of SARS-CoV-2 in an Italian northern area: comparison of Real Time RT PCR cycle threshold (Ct) values in three epidemic periods

Licia Veronesi  1 , Maria Eugenia Colucci  2 , Cesira Pasquarella  3 , Luca Caruso  4 , Mostafa Mohieldin Mahgoub Ibrahim  5 , Roberta Zoni  6 , Massimiliano Pergreffi  7 , Carlo Arcuri  8 , Chiara Seidenari  9 , Isabella Viani  10 , Emanuela Capobianco  11 , Sandra Mezzetta  12 , Paola Affanni  13
Affiliations
Comparative Study

Virological surveillance of SARS-CoV-2 in an Italian northern area: comparison of Real Time RT PCR cycle threshold (Ct) values in three epidemic periods

Licia Veronesi et al. Acta Biomed. .

Abstract

Aim of the study was to investigate the differences in Ct values in nasopharingeal swabs collected in three SARS-CoV-2 epidemic periods: first one from February 23 to March 25 (14 days from lockdown started on March 11); the second one from March 26 to May 18 (14 days from the end of strict lockdown on May 4) and the third one from May 19 until June 15. Viral RNA was detected in nasopharyngeal swabs obtained both from inpatients and outpatients. COVID-19 infection was confirmed according to the Ct values for N1 and N2 genes ascertained by Real-Time RT-PCR assay as described by the CDC. We calculated the prevalence of nasopharyngeal swabs tested positive for SARS-CoV-2, the mean and median of the Cts and the percentage of samples equal or below the Ct value of 25 in the 3 periods considered. The average value of Ct increased, going from 24.80 in the first epidemic period to 26.64 in the second period to 28.50 in the third period (p <0.001). The percentage of samples with Ct lower than or equal to 25 also decreased sharply from 54.7% to 20.0%. These findings need to be integrated with epidemiological and clinical data.

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Conflict of interest statement

Each author declares that he or she has no commercial associations (e.g. consultancies, stock ownership, equity interest, patent/licensing arrangement etc.) that might pose a conflict of interest in connection with the submitted article

References

    1. Epicentro. Epidemia COVID-19 Aggiornamento nazionale 23 giugno 2020. https://www.epicentro.iss.it/coronavirus/bollettino/Bollettino-sorveglia.... (accessed 28 June 2020)
    1. Epicentro. Epidemia COVID-19 Aggiornamento nazionale 23 giugno 2020 (Appendice) https://www.epicentro.iss.it/coronavirus/bollettino/Bolletino-sorveglian.... (accessed 28 June 2020)
    1. Colucci ME, Veronesi L, Bracchi MT, et al. On field vaccine effectiveness in three periods of 2018/2019 influenza season in Emilia-Romagna Region. Acta Biomed. 2019;90(9-S):21–27. - PMC - PubMed
    1. Affanni P, Colucci M.E, Bracchi , et al. Virological surveillance of influenza in the eight epidemic seasons after the 2009 pandemic in Emilia-Romagna (Northern Italy) Acta Biomed. 2020;90(9-S):35–44. - PMC - PubMed
    1. Bersanelli M, Scala S, Affanni P, et al. Immunological insights on influenza infection and vaccination during immune checkpoint blockade in cancer patients. Immunotherapy. 2020;12(2):105–110. - PubMed

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