Effect of Previous Infection and Vaccination on Incidence of Covid-19 among Healthcare Workers and Antibody Response

Aims: To correlate the effect of previous COVID-19 infection and vaccination on incidence of COVID -19 infection . 
Study Design: It is a prospective observational study. 
Place and Duration of Study: Eternal Heart Care Centre and Research Institute, Jaipur, India. 
Methodology: We included 405 healthcare workers with COVID-19 positive infection, with or without the symptoms. Clinical as well as hematological examination were done. 
Results: Our study showed 75.6% seropositivity rate even 6 months after vaccination in which seropositivity was significantly higher in people who had past history of COVID-19 .Antibody levels were highest when observed one month after vaccination. A decrease in antibody levels over time after vaccination is observed. Seropositivity rate was significantly higher in people who were less than 40 years old. 
Conclusion: A decrease in antibody levels over time after vaccination is observed and this  showed that the rate of infection decreases after receiving vaccination.