SARS-CoV-2 Breakthrough Infection and Viral Load among Healthcare Workers after COVID-19 Vaccines.

Journal of Medical VirologyEarly View LETTER TO THE EDITORFree Access SARS-CoV-2 breakthrough infection and viral load among healthcare workers after COVID-19 vaccines Gabriela Barbosa, Corresponding Author Gabriela Barbosa gabrielarbarbosa@hotmail.com grbarbosa@unifesp.br orcid.org/0000-0002-3386-8581 Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, São Paulo, São Paulo, Brazil Correspondence Gabriela Barbosa, Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, 781-Vila Clementino, São Paulo - SP, Brazil. Email: gabrielarbarbosa@hotmail.com, grbarbosa@unifesp.brSearch for more papers by this authorAna P. C. Chaves, Ana P. C. Chaves orcid.org/0000-0003-0321-6977 Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, São Paulo, São Paulo, BrazilSearch for more papers by this authorLuciano de Souza Luna, Luciano de Souza Luna orcid.org/0000-0002-3552-5507 Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, São Paulo, São Paulo, BrazilSearch for more papers by this authorNancy Bellei, Nancy Bellei orcid.org/0000-0001-6080-5693 Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, São Paulo, São Paulo, BrazilSearch for more papers by this author Gabriela Barbosa, Corresponding Author Gabriela Barbosa gabrielarbarbosa@hotmail.com grbarbosa@unifesp.br orcid.org/0000-0002-3386-8581 Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, São Paulo, São Paulo, Brazil Correspondence Gabriela Barbosa, Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, 781-Vila Clementino, São Paulo - SP, Brazil. Email: gabrielarbarbosa@hotmail.com, grbarbosa@unifesp.brSearch for more papers by this authorAna P. C. Chaves, Ana P. C. Chaves orcid.org/0000-0003-0321-6977 Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, São Paulo, São Paulo, BrazilSearch for more papers by this authorLuciano de Souza Luna, Luciano de Souza Luna orcid.org/0000-0002-3552-5507 Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, São Paulo, São Paulo, BrazilSearch for more papers by this authorNancy Bellei, Nancy Bellei orcid.org/0000-0001-6080-5693 Laboratory of Clinical Virology, Infectious Diseases Division, Universidade Federal de São Paulo, UNIFESP, São Paulo, São Paulo, BrazilSearch for more papers by this author First published: 01 February 2022 https://doi.org/10.1002/jmv.27639AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Dear Editor, As one of the largest countries in the world, Brazil has administered over 380 million doses of COVID-19 vaccines, which counts to approximately 67% of its population being considered fully vaccinated.1 In late January 2021, the national immunization campaign started after an emergency authorization for two vaccines: Sinovac-CoronaVac (inactivated virus) and ChAdOx1 nCoV-19 (nonreplicant adenoviral vector).2 The interim data release for the ChAdOx1 nCoV-19 demonstrated a 70.4% overall efficacy against SARS-CoV-2.3 The claimed data of CoronaVac efficacy was around 50%.4, 5 According to the CDC USA—Centers for Disease Control, a vaccine breakthrough infection is defined as the detection of SARS-CoV-2 RNA collected from an individual 14 days after they have received two doses of an authorized vaccine.6 Data of COVID-19 vaccines breakthrough infections are still limited. In this sense, we aimed to assess the SARS-CoV-2 positivity rates and cycle threshold (Ct) median value (inferred viral load) among vaccinated healthcare workers (HCW) with one or two doses of either CoronaVac or ChAdOx1, in a university hospital in São Paulo, Brazil. This retrospective cohort study was conducted in compliance with institutional guidelines, approved by the Ethics Committee of Universidade Federal de São Paulo (CEP/UNIFESP n. 29407720.4.0000.5505). Data were obtained regarding COVID-19 diagnostics performed at Hospital São Paulo, Brazil. From January 21 to October 15, we investigated all vaccinated HCW and performed a real-time quantitative polymerase chain reaction test (GeneFinder Kit; OSANG Healthcare) to detect SARS-CoV-2. The tests were immediately available to all HCW that presented 2–3 days of mild symptoms such as fever and/or rhinorrhea, cough, sore throat, anosmia, and ageusia at the time of the sample collection (nasopharyngeal swab). A positive result was considered with a Ct ≤ 40 for at least two SARS-CoV-2 genes (RdRp, E, and N).7 We considered the lowest Ct for the analysis. To better understand the inferred viral load, we calculated the median and interquartile range (IQR: 25%–75%). We included 1059 vaccinated HCW, aged 19–72 years old, of which 738 received CoronaVac (69.7%) and 321 the ChAdOx1 (30.3%). The overall positivity was 18.1%. In the CoronaVac group, for those with one dose, we found a positivity of 30%, with a Ct median of 23 (range: 14–38; IQR: 21–28). For those who received two doses, 19% tested positive and had a Ct median of 19 (range: 12–38; IQR: 17–24). Considering only the breakthrough infections, the positivity was 18% Ct median of 19 (range: 12–38; IQR: 16–24). In the ChAdOx1 group, for those with one dose, 18.3% tested positive, with a Ct median of 22 (range: 13–36; IQR: 18–26). For those with two doses, 23.7% were positive and the Ct median was 19 (range: 12–37; IQR: 16–29). Considering only the breakthrough infections, the positivity was 13% Ct median of 19 (range: 12–37; IQR: 16–30). Table 1 describes SARS-CoV-2 among vaccinees and days after one or two doses. Table 1. SARS-CoV-2 positivity rates among healthcare workers (HCW) after vaccination Days after vaccination CoronaVac ChAdOx1 nCoV-19 Positive (n = 146) Tested (n = 738) (%) Median Ct p Value** p < 0.05 (Kruskal–Wallis test). Positive (n = 34) Tested (n = 223) (%) Median Ct p Value** p < 0.05 (Kruskal–Wallis test). Dose 1 Days 1–14 15 37 (40.5) 20 >0.99 2 11 (18.2) 20 NA Days 15 later 12 53 (22.6) 22.5 0.44 20 109 (18.3) 23 >0.99 Dose 2 Days 1–14 7 28 (25) 18 0.13 1 24 (4.1) 16 NA Days 15 later 112 620 (18) 19 >0.99 23 117 (13) 22 0.6 Abbreviations: Ct, cycle threshold; NA, not applicable. * p < 0.05 (Kruskal–Wallis test). We did not observe a significant change in the viral load regardless of vaccine type or the number of doses. Remarkably, the observed IQR for Ct values of breakthrough infections obtained in the CoronaVac group poses a risk of virus transmission, since Ct < 28 is related to infectivity.8 Nevertheless, it is crucial to state that no hospitalizations were registered among the studied HCW, reinforcing the importance of vaccines. Globally immunization is progressing. As the variants of concern are still threatening the world, countries such as the United Kingdom and Israel that had massive vaccination campaigns experienced their numbers of SARS-CoV-2 positive tests rising again.9, 10 Nonetheless, the extension of vaccination coverage in a scenario of SARS-CoV-2 viral evolution remains a challenge. Understanding the real chance of attenuating SARS-CoV-2 transmission will then safely allow suspension of wearing masks and physical distancing. ACKNOWLEDGMENTS Gabriela Barbosa is a fellow of the São Paulo Research Foundation (FAPESP), Grant 2020/11719-0, Ana Paula Cunha Chaves and Luciano de Souza Luna is a fellow of the Coordination for the Improvement of Higher Education Personnel (CAPES). This study was supported by MCIT – FINEP/RTR/PRPq/REDECOVI-19 (27968*15). CONFLICT OF INTEREST The authors declare that there are no conflict of interest. DATA AVAILABILITY STATEMENT The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. REFERENCES 1 BRASIL. Vacinação contra a Covid-19 no Brasil. Ministério da Saúde. 2021. Accessed January 5, 2022. https://www.gov.br/saude/pt-br/vacinacaoGoogle Scholar 2 Ministerio da Saude. Vacinação contra a Covid-19 no Brasil. 2021. Accessed July 15, 2021. https://www.gov.br/saude/pt-br/vacinacao/Google Scholar 3Voysey M, Clemens SAC, Madhi SA, et al. 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GeneFinder™ COVID-19 PLUS Real Amp Kit Instructions for Use. 2020. Google Scholar 8Kim M-C, Cui C, Shin K-R, et al. Duration of culturable SARS-CoV-2 in hospitalized patients with Covid-19. N Engl J Med. 2021; 384(7): 671- 673. doi:10.1056/NEJMc2027040CrossrefPubMedWeb of Science®Google Scholar 9 WHO. The United Kingdom_WHO Coronavirus Disease (COVID-19) Dashboard With Vaccination Data_WHO Coronavirus (COVID-19) Dashboard With Vaccination Data. World Health Organization. 2021. Accessed October 15, 2021. https://covid19.who.int/region/euro/country/gbGoogle Scholar 10 WHO. Israel_WHO Coronavirus Disease (COVID-19) Dashboard With Vaccination Data _ WHO Coronavirus (COVID-19) Dashboard With Vaccination Data. World Health Organization. 2021. Accessed October 15, 2021. https://covid19.who.int/region/euro/country/ilGoogle Scholar Early ViewOnline Version of Record before inclusion in an issue ReferencesRelatedInformation