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Rapid Decline of SARS-CoV-2 Viral Load in Single vs. Double-Dose (Short-Interval <6 Weeks) ChAdOx nCoV-19 Vaccinated Health-Care Workers

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Abstract

The present work was carried out during the emergence of Delta Variant of Concern (VoC) and aimed to study the change in SARS CoV-2 viral load in Covishield vaccinated asymptomatic/mildly symptomatic health-care workers (HCWs) to find out the optimum isolation period. The SARS CoV-2 viral load was carried out in sequential samples of 55 eligible HCWs which included unvaccinated (UnV; n = 11), single-dose vaccinated (SDV, n = 20) and double-dose vaccinated [DDV, n = 24; short-interval (<6 weeks)] subjects. The mean load of envelope (E) gene on day 5 in SDV [0.42 × 105 copies/reaction] was significantly lower as compared to DDV [6.3 × 105 copies/reaction, P = 0.005] and UnV [6.6 × 105 copies/reaction, P = 0.001] groups. The rate of decline of SARS CoV-2 viral load in the initial 5 days of PCR positivity was significantly higher in SDV as compared to that in DDV (Mean log decline 0.39 vs. 0.19; P < 0.001). This was possibly due to interference of adenoviral immunity of first dose of adenovirus-vectored vaccine in double-dose vaccinated HCWs who had received vaccines within a shorter interval (<6 weeks).

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Author notes

  1. Arnab Ghosh and Poonam Kanta have contributed equally to this work.

Authors and Affiliations

  1. Department of Virology, Post-Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, 160012, India

    Arnab Ghosh, Poonam Kanta, Manisha Ramola, Kapil Goyal & Mini P. Singh

  2. Department of Internal Medicine, Post-Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, 160012, India

    Ritin Mohindra, Roop Kishore & Vikas Suri

  3. Department of Community Medicine and School of Public Health, Post-Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, 160012, India

    P. V. M. Lakshmi, Chanderkanta Chauhan & Manisha Sharma

  4. National Centre for Disease Control (NCDC), New Delhi, India

    Partha Rakshit, Kalaiarasan Ponnusamy & Tanzin Dikid

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  1. Arnab Ghosh
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Contributions

Conceptualization, data analysis and writing manuscript—AG; Methodology (Real-time PCRs)—PK, Sample collection and record maintenance—MR, Recruitment of vaccinated and unvaccinated subjects—RM, Result reporting and manuscript review and editing—KG, Communication with study subjects and their follow-up—RK, Clinical investigation of the study subjects and final decision on their health status—VS, Epidemiological data collection and communication with HCWs for recruitment in the study—PVML, Epidemiological data collection—Manisha & Chanderkanta, Analysis of NGS data—PR, Sample preparation and NGS testing of samples—KP, Quality control of NGS samples and checking the appropriateness of the samples sent for NGS—TD, Overall project administration and editing of manuscript—MPS.

Corresponding author

Correspondence to Mini P. Singh.

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Ethical Approval and Consent to Participate

The study was approved by institutional ethics committee (IEC no. Int/IEC/2021/SPL-949 dated 10.06.2021.

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Ghosh, A., Kanta, P., Ramola, M. et al. Rapid Decline of SARS-CoV-2 Viral Load in Single vs. Double-Dose (Short-Interval <6 Weeks) ChAdOx nCoV-19 Vaccinated Health-Care Workers. Curr Microbiol 81, 95 (2024). https://doi.org/10.1007/s00284-023-03603-7

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