Severity of COVID-19 Disease in Vaccinated and Non Vaccinated COVID-19 Positive Cases: A Cross-sectional Study

Introduction: Coronavirus Disease-2019 (COVID-19) vaccine was reported to be used in China, after the outbreak of Coronavirus. COVID-19 vaccine requires validation of efficacy and adverse reactions as target vaccine population include high risk over the age of 60, medical frontline workers and people working in essential industries. After Spanish flu, COVID-19 pandemic is most devasting situation in the world.

Aim: To evaluate the effectiveness of COVID-19 vaccine in COVID-19 positive vaccinated cases compared to non vaccinated cases.

Materials and Methods: This cross-sectional study was conducted in Government Super Specialty Hospital Andhra Pradesh, India, from July to September 2021. COVID-19 positivity was confirmed by Reverse Transcription Polymerase Chain Reaction (RT-PCR) test in vaccinated and non vaccinated patients, admitted in a Government Super Specialty Hospital. Severity of the disease was studied in 1423 non vaccinated and 601 vaccinated cases of all age group above 18 years. Patients were categorised based on symptoms and oxygen saturation (SpO2) in to Mild-SpO2 >94%, Moderate- SpO2 <94%, Severe- SpO2 <90%. Patients were subdivided into three groups based on age 18-44 years, 45-64 years and ≥65 years age. Data was collected and tabulated using Microsoft excel and Statistical Package for the Social Sciences (SPSS) version 15.0. The statistics of percentage was used.

Results: A total of 2024 COVID-19 positive cases were studied, out of which, 1423 were non vaccinated and 601 were vaccinated. Among non vaccinated group of 1423 cases, 712 cases had mild symptoms, 510 patients were of moderate symptoms, 201 patients were of severe symptoms. In 601 vaccinated cases, mild cases were 352, moderate cases were 185 with SpO2 <94%-90%, 64 cases are severe with SpO2 <90%. In this study the vaccinated patients had less severe disease with mild symptoms, in the cases of present study from COVID-19 compared to non vaccinated cases.

Conclusion: Vaccine effectiveness was noted after two doses. Vaccinated people had less severe symptoms and disease compared to non vaccinated people. Finding would support the effort to maximise vaccine with two doses among vulnerable population.