COVID 19 Vaccine Breakthrough Infection among Health Care Workers.

ABSTRACT

Background Mass vaccination is considered the primary strategy for reducing the impact of COVID-19, and it has been implemented globally. Objective To study the extent of SARS-CoV-2 infection and breakthrough infection among the HCWs who were fully vaccinated for at least 14 days and investigated the relation between neutralizing antibody response and breakthrough infection. Method This study was a retrospective cohort study among health care workers at Dhulikhel Hospital Kathmandu University Hospital from December 2021 to October 2022. The interviews with semi structured questionnaire were conducted in person or over phone. Out of 1450 participants 137 fully vaccinated HCWs without breakthrough infection were randomly selected for the prospective serological cohort. Result Out of 1079 participants' majority (51.8%) were of age 25-34 years. Two thirds (66.7%) were females. More than half of participant (54.7%) had infection with SARS-CoV-2 at least once whereas more than one third people (35%) had reported SARS-CoV-2 infection 14 days after receiving full vaccination. Infection after vaccination had less moderate and sever/critical illness and less need for hospitalization as compared to infection before vaccination. Staffs who were directly involved in patient care had higher chance of breakthrough infection compared to those not involved directly in patient care. Those who had prior infection or booster dose had relatively higher antibody level and participants with low level of antibody had higher chance for breakthrough infection (35.3%) than participants with moderate to high level of antibody (11.9%). Conclusion Vaccinations significantly decreased severe diseases and the need for hospitalizations. Breakthrough infection was higher among the health care workers involved in direct patient care and with low level of antibody.