Occurrence and Severity of COVID-19 among vaccinated and unvaccinated individuals in Nepal: A retrospective cohort study



Ethical approval was obtained following which data collection was planned for the study via Google form and through different media (Facebook page, Viber, Email, Personal Network). Over 800 responses were obtained and over 300 blood samples were collected for the detection of antibody titer.


2021 Apr 1 to 2021 Dec 30


Ministry of Health and Population (MoHP)


Kathmandu, Lalitpur, and Bhaktapur


COVID 19 outbreak has been declared a public health emergency of international concern and this disease has spread in many countries of the world causing many human deaths. The disease is novel with less evidence base to formulate correct clinical decisions and every human being of every age both sexes are equally susceptible to the disease. Many countries are facing a second wave of the disease with the changes in different variants of the virus. The vaccine is the most preferred measure to combat the disease. WHO suggested that also in fully vaccinated people COVID 19 disease may occur but they are much less likely to develop severe disease, be hospitalized, or die. To date, 13 vaccines of different companies around the world have been approved for full use against the infection so far and a significant number of vaccines are undergoing investigations to explore the safety and efficacy in humans. As of March 18, 2021, 1.6 million people have been vaccinated against COVID-19 in Nepal.

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) initiates a humoral immune response that produces antibodies against specific viral antigens such as the nucleocapsid (N) protein and spike (S) protein, which include specific anti-S protein antibodies that target the spike’s S1 protein subunit and receptor-binding domains (RBD). These antibodies stick around to defend against the invader in case it ever comes back. Vaccines teach our body to mimic this response without actually getting sick. This is why antibodies are developed after natural infection with a virus and after getting a vaccine. So this study aims to find out the severity of illness among COVID-positive individuals, compare the severity of reported signs and symptoms of COVID 19, and level of antibody among vaccinated and non-vaccinated individuals.


  • To find out signs and symptoms of COVID 19 among vaccinated and unvaccinated individuals.
  • To assess the severity of self-reported signs and symptoms of disease among COVID test positive individuals.
  • To compare the severity of self-reported signs and symptoms of disease among vaccinated and unvaccinated individuals.
  • To find out the outcome (Death or recovery) of the disease among vaccinated and unvaccinated individuals.
  • To assess the level of antibody (IgG) among the vaccinated and unvaccinated population in Kathmandu Valley.
  • To monitor the progress of vaccine-induced immunity during six months.
  • To compare natural immunity with vaccine-induced immunity during six months.

This study is expected to generate evidence on the occurrence, severity, and level of the antibody of COVID-19 diseases among the vaccinated and unvaccinated population. The results obtained from this study will be useful for the planners and policymakers to make COVID -19 related plans and policies and to conduct interventions for the COVID-19 disease.