Determinants of COVID-19 Breakthrough Infections and Severity in ChAdOx1 nCoV-19–Vaccinated Priority Groups

Abstract

The current analysis is a part of an ongoing observational study that began in February 2021 in the Sir Sunder Lal Hospital (Varanasi, Uttar Pradesh) in northern India and is expected to continue until June 2022. This analysis aimed to delineate the clinical presentation and risk factors of occurrence and severity of COVID-19 in vaccinated individuals. The study enrolled health-care workers and the elderly receiving the COVID-19 vaccine at one of three centers linked to the study hospital. The participants received the ChAdOx1 nCoV-19 (Oxford-AstraZeneca) vaccine based on the chimpanzee adenovirus platform (manufactured in India by the Serum Institute of India). The adenovirus codes for the spike (S) protein of SARS-CoV-2. Participants were contacted by phone at pre-decided intervals and questioned about the occurrence of COVID-19, clinical presentation, severity, and persistence of symptoms. A logistic regression analysis was performed to predict the risk factors of occurrence and severity of COVID-19. Of the 1,500 participants included in the analysis, 418 developed COVID-19 (27.9%). Fever was the most common symptom (72%), followed by cough (34%) and rhinitis (26%). Cardiovascular involvement was seen in more than 2% of individuals, and 11% had post-COVID-19 complaints. Regression analysis showed 1.6 times greater odds of contracting the disease in females and in those younger than 40 years, 1.4 times greater odds in individuals who were overweight, and 2.9 times greater odds in those receiving only one dose, compared with respective comparators. Individuals receiving two doses at a gap of ≤ 30 days had 6.7 times greater odds of infection than those receiving at a > 60-day interval. There was no association between COVID-19 occurrence in the vaccinees and pre-vaccination history of SARS-CoV-2 infection. Males were at a 3.6 times greater risk, and persons with preexisting lung disease—mainly asthma—had a 5.9 times greater risk of experiencing from moderate to severe COVID-19 than comparators. Although an extended interval between the two vaccine doses seems to be a better strategy, gender differences and an association of asthma phenotypes with COVID-19 need to be explored.

Vaccine Breakthrough Infections Among Healthcare Workers in a COVID-19-Designated Tertiary Care Government Hospital in Sikkim

“…It was observed that as the dose gap between the two vaccine doses increased, the occurrence of COVID-19 infection decreased. Kaur et al, in their study on risk factors for the occurrence of COVID-19 in people who had been vaccinated, have reported that there was an increased risk of acquiring infection post-vaccination when the interval between the two doses was ≤ 30 days when compared to a dose interval of > 60 days [ 30 ]. Our report is also consistent with the exploratory findings in randomized controlled trials of the ChAdOx1 nCoV-19 (AZD1222) vaccine where the vaccine efficacy was reported to be higher after the second dose when the dose interval was longer [ 6 ].…”