‘Anatomy of SARS-CoV-2 outbreak of ‘vaccinated’: An observational case-control study of COVID-19 breakthrough infections, COVID-19 appropriate behavior and anti-spike-IgG response as a correlate of protection in Medical college students at Rural Medical College, India
Authors: Chavan Monika , Gayatri Sowmya , Patil Suvarna , Deshpande Janhavi , Yadav Arvind , Nakate Prasanna , Shelke Yogendra , Nillawar Anup N 
Published: January 2022

ABSTRACTIntroductionBreakthrough infections about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported worldwide in both partially or completely vaccinated individuals irrespective of the type of vaccine. India, also emerged as the vaccine powerhouse producer, initiating the world’s one of the largest vaccination drives since January 16, 2021, with two vaccines named, BBV-152(COVAXIN™) and AZD1222 (COVISHIELD™). Breakthrough cases are reported from all over the globe for all kinds of vaccines. This is the investigation report into the outbreak of breakthrough COVID-19 infections at one of the medical colleges in Rural India unraveled in early October 2021. This report underscores the role of COVID-19 appropriate behavior along with vaccination and the role of IgG in evaluating immunity generated through vaccination.ObjectiveThe study objective was to 1. Clinically characterize the recent breakthrough infection of COVID-19 (SARS-CoV-2) infection among (students) vaccinated in BKL Walawalkar Rural Medical College. 2. To evaluate ‘COVID-19 appropriate behavior’ (CAB) in cases and controls. 3. To evaluate COVID-19 anti spike IgG in the cases in comparison with the controlMethodsA total of 74 students studying at BKL Walawalkar Rural Medical College and vaccinated for COVID-19 were included in the study. RT-PCR diagnosis was done from 5 to 10 October 2021. The breakthrough infection in the cases was characterized using self-assessment questionnaires in comparison to the controls. The cases were assessed clinically and also using biochemical parameters. Both cases and controls were also assessed for their adherence to COVID-19 appropriate behavior using a separate semi-quantitative questionnaire and scoring system.ResultsIn our study, out of the total subjects, 50% of Covaxin recipients had experienced vaccine breakthrough infection and 20% of Covishield recipients experienced breakthrough infection. Also, 6 out of the 35 cases were asymptomatic, and the rest were either having mild symptoms. None of them required any hospitalization or O2 therapy. The CAB score was lower in the cases when compared to controls. All the vaccine recipients show seroconversion. Anti-spike IgG antibodies titers are dynamic over time and across the clinically distinct groups. Irrespective of varying IgG titer, the vaccine protects against severity and possibly mortality.ConclusionThe need for better awareness of COVID-19 appropriate methods as an alternative to and additive to vaccination is necessary to control the transmission of COVID-19 infection and decrease the disease severity. Vaccines are effective against preventing severe disease and possibly mortality. The use of serum anti-spike COVID-19 IgG is restricted to know the status of SARS-CoV-2 seroconversion.