First and second doses of Covishield vaccine provided high level of protection against SARS-CoV-2 infection in highly transmissible settings: results from a prospective cohort of participants residing in congregate facilities in India

• Published in: BMJ global health Vol. 7; no. 5; p. e008271
• Main Authors: Tsundue, Tenzin, Namdon, Tenzin, Tsewang, Tenzin, Topgyal, Sonam, Dolma, Tashi, Lhadon, Dekyi, Choetso, Tsering, Woesal, Tenzin, Yangkyi, Tenzin, Gupta, Amita, Peters, David, Paster, Zorba, Phunkyi, Dawa, Sadutshang, Tsetan Dorji, Chaisson, Richard E, Dorjee, Kunchok
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd 01-05-2022; BMJ Publishing Group LTD; BMJ Publishing Group
• Subjects: Adult; Age; Boarding schools; ChAdOx1 nCoV-19; Chronic obstructive pulmonary disease; Cohort Studies; Coronaviruses; COVID-19; COVID-19 - epidemiology; COVID-19 - prevention & control; COVID-19 diagnostic tests; COVID-19 Vaccines; Disease transmission; Epidemics; Epidemiology; Female; Global health; Health risks; Health surveillance; Hepatitis; Humans; Infections; Male; Monasteries; Nursing homes; Original Research; Pandemics; Prospective Studies; Public Health; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Task forces; Tuberculosis; Vaccines; India; COVID-19; Epidemiology; Public Health
• ISSN: 2059-7908; 2059-7908
• DOI: 10.1136/bmjgh-2021-008271

ObjectivesThis study aimed to determine the effectiveness of Covishield vaccine among residents of congregate residential facilities.DesignA prospective cohort study in congregate residential facilities.SettingDharamshala, Himachal Pradesh, India, from December 2020 to July 2021.ParticipantsResidents of all ages in seven facilities—three monasteries, two old age homes and two learning centres—were enrolled.ExposuresFirst and second doses of Covishield vaccine against SARS-CoV-2 infection.Main outcomes measuresPrimary outcome was development of COVID-19. Secondary outcome was unfavourable outcomes, defined as a composite of shortness of breath, hospitalisation or death. Vaccine effectiveness (%) was calculated as (1−HR)×100.ResultsThere were 1114 residents (median age 31 years) participating in the study, 82% males. Twenty-eight per cent (n=308/1114) were unvaccinated, 50% (n=554/1114) had received one dose and 23% (n=252/1114) had received two doses of Covishield. The point prevalence of COVID-19 for the facilities ranged from 11% to 57%. Incidence rates (95% CI) of COVID-19 were 76 (63 to 90)/1000 person-months in the unvaccinated, 25 (18 to 35)/1000 person-months in recipients of one dose and 9 (4 to 19)/1000 person-months in recipients of two doses. The effectiveness of first and second doses of Covishield were 71% (adjusted HR (aHR) 0.29; 95% CI 0.18 to 0.46; p<0.001) and 80% (aHR 0.20; 95% CI 0.09 to 0.44; p<0.001), respectively, against SARS-CoV-2 infection and 86% (aHR 0.24; 95% CI 0.07 to 0.82; p=0.023) and 99% (aHR 0.01; 95% CI 0.002 to 0.10; p<0.001), respectively, against unfavourable outcome. The effectiveness was higher after 14 days of receiving the first and second doses, 93% and 98%, respectively. Risk of infection was higher in persons with chronic hepatitis B (aHR 1.78; p=0.034) and previous history of tuberculosis (aHR 1.62; p=0.047).ConclusionCovishield was effective in preventing SARS-CoV-2 infection and reducing disease severity in highly transmissible settings during the second wave of the pandemic driven by the Delta variant.