SARS-CoV-2 Nasopharyngeal Viral Load in Individuals Infected with BA.2, Compared to Alpha, Gamma, Delta and BA.1 Variants: A Single-Center Comparative Analysis
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Clinical Department
Abstract
Background: SARS-CoV-2 has evolved, leading to the emergence of new Variants Of Concern (VOCs) with significant impact on transmissibility. Although the transmission process is complex, higher nasopharyngeal viral load (NP-VL) can be considered as a proxy for greater transmissibility.
Objectives: The aim of this analysis was to compare NP-VL across a set of representative VOCs observed in mildly symptomatic patients.Study designObservational single-center comparative analysis of patients with early mild-to-moderate COVID-19, enrolled within the early treatment access program of Lazzaro Spallanzani Institute (March 2021-March 2022). NP-VL before drug administration was estimated through RT-PCR, based on cycle threshold values (CTs); VOCs were identified by Sanger sequencing. VOCs’ average treatment effect (ATE) was estimated on the CTs fitted in the log2 scale, controlling for potential confounders.
Results: A total of 707 patients was included. VOCs were: 10% Alpha, 3% Gamma, 34% Delta, 34% BA.1, 19% BA.2. Mean CTs for BA.1 and BA.2 were lower than Delta and BA.1, respectively. After adjusting for calendar time, age, immunodeficiency and vaccination, CTs for Gamma were lower than those seen for Alpha and higher than Delta, for Delta were similar to BA.1, for BA.2 were lower than Delta and BA.1.
Conclusions: Our analysis shows higher NP-VL of BA.2 compared to previously circulating VOCs, even after controlling for factors potentially contributing to the amount of nasopharyngeal viral RNA, included vaccination, supporting the increased transmissibility of BA.2. Further studies are necessary to clarify this mechanism and to provide guidance for public health measures.
Note:
Funding Information: The study was performed in the framework of the SARS-CoV-2 surveillance and response program implemented by the Lazio Region Health Authority. This study was supported by funds to the National institute for Infectious Diseases “Lazzaro Spallanzani”, IRCCS, Rome (Italy), from Italian Ministry of Health (Programme CCM 2020; Ricerca Corrente - Linea 1 on emerging and re-emerging infections) and from the European Commission - Horizon 2020 (CoNVat, Grant agreement ID 101003544; KRONO, Grant agreement ID 101005075).
Declaration of Interests: The authors declare no conflict of interest for the present study.
Ethics Approval Statement: The study was approved by the Scientific Committee of the Italian Medicines Agency (AIFA) and by the Ethical Committee of the National Institute for Infectious Diseases “Lazzaro Spallanzani” in Rom e, Italy, as National Review Board for COVID-19 pandemic in Italy (approval number 380/2021). All consecutive patients presenting at our Institute to be evaluated for early treatment, from 23rd of March, 2021 to 15th of March, 2022, were enrolled after having signed the specific informed consent.
Mastrorosa, Ilaria and Lepri, Alessandro Cozzi and Colavita, Francesca and Lalle, Eleonora and Mazzotta, Valentina and Cimaglia, Claudia and Paulicelli, Jessica and Matusali, Giulia and Fabeni, Lavinia and Carletti, Fabrizio and Rosati, Silvia and Vita, Serena and Giannico, Giuseppina and Piselli, Pierluca and Biliotti, Elisa and Al Moghazi, Samir and Mosti, Silvia and Girardi, Enrico and Nicastri, Emanuele and Garbuglia, Anna Rosa and Maggi, Fabrizio and Vaia, Francesco and Antinori, Andrea, SARS-CoV-2 Nasopharyngeal Viral Load in Individuals Infected with BA.2, Compared to Alpha, Gamma, Delta and BA.1 Variants: A Single-Center Comparative Analysis. Available at SSRN: https://ssrn.com/abstract=4175889 or http://dx.doi.org/10.2139/ssrn.4175889
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
Scientific Institute for Research, Hospitalization and Healthcare (IRCCS) - Lazzaro Spallanzani National Institute for Infectious Diseases - INMI ( email )
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