Effectiveness of BBV152/Covaxin and AZD1222/Covishield vaccines against severe COVID-19 and B.1.617.2/Delta variant in India, 2021: a multi-centric hospital-based case-control study.

OBJECTIVES: India introduced BBV152/Covaxin and AZD1222/Covishield vaccines in January 2021. We estimated the effectiveness of these vaccines against severe COVID-19 among individuals aged ≥45 years. METHODS: We did a multi-centric, hospital-based, case-control study between May and July 2021. Cases were severe COVID-19 patients, and controls were COVID-19 negative individuals from 11 hospitals. Vaccine effectiveness (VE) was estimated for complete (2 doses ≥ 14 days) and partial (1 dose ≥ 21 days) vaccination; interval between two vaccine doses and vaccination against the Delta variant. We used the random effects logistic regression model to calculate the adjusted odds ratios (aOR) with a 95% confidence interval (CI) after adjusting for relevant known confounders. RESULTS: We enrolled 1143 cases and 2541 control patients. The VE of complete vaccination was 85% (95% CI: 79-89%) with AZD1222/Covishield and 71% (95% CI: 57-81%) with BBV152/Covaxin. The VE was highest for 6-8 weeks between two doses of AZD1222/Covishield (94%, 95% CI: 86-97%) and BBV152/Covaxin (93%, 95% CI: 34-99%). The VE estimates were similar against the Delta strain and sub-lineages. CONCLUSION: BBV152/Covaxin and AZD1222/Covishield were effective against severe COVID-19 among the Indian population during the period of dominance of the highly transmissible Delta variant in the second wave of the pandemic. An escalation of two-dose coverage with COVID-19 vaccines is critical to reduce severe COVID-19 and further mitigate the pandemic in the country.

Effectiveness of COVID-19 vaccine (Covaxin) against breakthrough SARS-CoV-2 infection in India.

India approved COVID-19 vaccine called Covaxin, developed by the Indian Council of Medical Research and Bharat Biotech Ltd. The primary objective of the study was to estimate the effectiveness of Covaxin in preventing breakthrough SARS-CoV-2 infection in healthcare workers (HCWs). A test-negative matched case-control study was conducted among HCWs of tertiary care hospital in Eastern India. Any HCW who tested positive for COVID-19 using RT-PCR during April and May 2021 was taken as the case. The HCWs who tested negative for COVID-19 by RT-PCR were considered as controls after matching with the date of testing and profession of the cases. Vaccination data were collected from the institution's vaccine database and recall. In case of discrepancy, it was confirmed from the CoWIN portal (cowin.gov.in). The sample size was 670 participants (335 pairs). Conditional logistic regression models were used to calculate the adjusted odds ratio for breakthrough SARS-CoV-2 infection. Vaccine effectiveness was calculated using the following formula: VE = (1-aOR) × 100%. Sensitivity analysis was done for effectiveness of Covaxin, excluding Covishield vaccination. The mean age of participants was 29.1 years (SD = 7.1), and the majority were males (55.2%). Among the study participants, 60% were completely vaccinated, 18.51% were partially vaccinated, and 21.49% were unvaccinated. After adjusting for age, gender, type of household and past history of COVID-19 disease in conditional logistic models, the vaccine effectiveness was 22% (aOR 0.78, 95% CI: 0.52-1.17; p = .233). Sensitivity analysis with Covaxin showed an effectiveness of 29% (aOR 0.71, 95% CI: 0.47-1.08; p = .114) for preventing breakthrough SARS-CoV-2 infection.

Prophylactic Role of Ivermectin in Severe Acute Respiratory Syndrome Coronavirus 2 Infection Among Healthcare Workers.

Introduction Healthcare workers (HCWs) are vulnerable to getting infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Preventing HCWs from getting infected is a priority to maintain healthcare services. The therapeutic and preventive role of ivermectin in coronavirus disease 2019 (COVID-19) is being investigated. Based on promising results of in vitro studies of oral ivermectin, this study was conducted with the aim to demonstrate the prophylactic role of oral ivermectin in preventing SARS-CoV-2 infection among HCWs at the All India Institute of Medical Sciences (AIIMS) Bhubaneswar. Methods A prospective cohort study was conducted at AIIMS Bhubaneswar, which has been providing both COVID and non-COVID care since March 2020. All employees and students of the institute who provided written informed consent participated in the study. The uptake of two doses of oral ivermectin (300 µg/kg/dose at a gap of 72 hours) was considered as exposure. The primary outcome of the study was COVID-19 infection in the following month of ivermectin consumption, diagnosed as per Government of India testing criteria (real-time reverse transcriptase polymerase chain reaction [RT-PCR]) guidelines. The log-binomial model was used to estimate adjusted relative risk (ARR), and the Kaplan-Meier failure plot was used to estimate the probability of COVID-19 infection with follow-up time. Results Of 3892 employees, 3532 (90.8%) participated in the study. The ivermectin uptake was 62.5% and 5.3% for two doses and single dose, respectively. Participants who took ivermectin prophylaxis had a lower risk of getting symptoms suggestive of SARS-CoV-2 infection (6% vs 15%). HCWs who had taken two doses of oral ivermectin had a significantly lower risk of contracting COVID-19 infection during the following month (ARR 0.17; 95% CI, 0.12-0.23). Females had a lower risk of contracting COVID-19 than males (ARR 0.70; 95% CI, 0.52-0.93). The absolute risk reduction of SARS-CoV-2 infection was 9.7%. Only 1.8% of the participants reported adverse events, which were mild and self-limiting. Conclusion Two doses of oral ivermectin (300 µg/kg/dose given 72 hours apart) as chemoprophylaxis among HCWs reduced the risk of COVID-19 infection by 83% in the following month. Safe, effective, and low-cost chemoprophylaxis has relevance in the containment of pandemic alongside vaccine.

Role of ivermectin in the prevention of SARS-CoV-2 infection among healthcare workers in India: A matched case-control study.

BACKGROUND: Ivermectin is one among several potential drugs explored for its therapeutic and preventive role in SARS-CoV-2 infection. The study was aimed to explore the association between ivermectin prophylaxis and the development of SARS-CoV-2 infection among healthcare workers. METHODS: A hospital-based matched case-control study was conducted among healthcare workers of AIIMS Bhubaneswar, India, from September to October 2020. Profession, gender, age and date of diagnosis were matched for 186 case-control pairs. Cases and controls were healthcare workers who tested positive and negative, respectively, for COVID-19 by RT-PCR. Exposure was defined as the intake of ivermectin and/or hydroxychloroquine and/or vitamin-C and/or other prophylaxis for COVID-19. Data collection and entry was done in Epicollect5, and analysis was performed using STATA version 13. Conditional logistic regression models were used to describe the associated factors for SARS-CoV-2 infection. RESULTS: Ivermectin prophylaxis was taken by 76 controls and 41 cases. Two-dose ivermectin prophylaxis (AOR 0.27, 95% CI, 0.15-0.51) was associated with a 73% reduction of SARS-CoV-2 infection among healthcare workers for the following month. Those involved in physical activity (AOR 3.06 95% CI, 1.18-7.93) for more than an hour/day were more likely to contract SARS-CoV-2 infection. Type of household, COVID duty, single-dose ivermectin prophylaxis, vitamin-C prophylaxis and hydroxychloroquine prophylaxis were not associated with SARS-CoV-2 infection. CONCLUSION: Two-dose ivermectin prophylaxis at a dose of 300 µg/kg with a gap of 72 hours was associated with a 73% reduction of SARS-CoV-2 infection among healthcare workers for the following month. Chemoprophylaxis has relevance in the containment of pandemic.

Transmission dynamics of the COVID-19 epidemic in India and modeling optimal lockdown exit strategies.

India imposed one of the world's strictest population-wide lockdowns on March 25, 2020 for COVID-19. We estimated epidemiological parameters, evaluated the effect of control measures on the epidemic in India, and explored strategies to exit lockdown. We obtained patient-level data to estimate the delay from onset to confirmation and the asymptomatic proportion. We estimated the basic and time-varying reproduction number (R0 and Rt) after adjusting for imported cases and delay to confirmation using incidence data from March 4 to April 25, 2020. Using a SEIR-QDPA model, we simulated lockdown relaxation scenarios and increased testing to evaluate lockdown exit strategies. R0 for India was estimated to be 2·08, and the Rt decreased from 1·67 on March 30 to 1·16 on April 22. We observed that the delay from the date of lockdown relaxation to the start of the second wave increases as lockdown is extended farther after the first wave peak-this delay is longer if lockdown is relaxed gradually. Aggressive measures such as lockdowns may be inherently enough to suppress an outbreak; however, other measures need to be scaled up as lockdowns are relaxed. Lower levels of social distancing when coupled with a testing ramp-up could achieve similar outbreak control as an aggressive social distancing regime where testing was not increased.