1923. Outcomes of the adsorbed Sinovac CoronaVac COVID-19 inactivated vaccine among the employee recipients in St. Luke’s Medical Center Quezon City: an observational cohort study
Authors: Uy Almira V , Doctor Medical , Llorin Ryan , Doctor Medical 
Published: December 2022

Background

Of the nine COVID-19 vaccines, the inactivated vaccine named CoronaVac, containing HB02 strain of SARS-CoV-2 created from Vero cells, created by the manufacturing company Sinovac was the first vaccine to arrive and be distributed in the Philippines, primarily in the private and government hospitals in Metro Manila. It is therefore important to determine the vaccine’s effectiveness and safety among its recipients, including the frontline healthcare workers (HCWs).

Methods

This was an observational cohort study which included HCWs from a tertiary hospital who have received one and/or two doses of CoronaVac from March 2021. The primary outcome of the study was to determine the clinical effectiveness of the vaccine in reducing risk of COVID-19 infection. The secondary outcome was the safety endpoint of the study vaccine.

Results

Out of the 2954 CoronaVac vaccinees, a total of 368 HCWs have been infected with SARS-CoV-2. 146 (4.94%) recipients have been infected with COVID-19 after receiving their first dose, while 222 (7.51%) tested positive after the second dose. 179 recipients reported of adverse reactions following immunization, with majority of these HCWs experiencing minor symptoms. The relative risk for COVID-19 infection among those given was at 15.7%, indicating the clinical effectiveness of the said vaccine. Receiving CoronaVac vaccine will reduce the risk of COVID-19 infection by 84.3%. Table 3.Percentage of infected HCWs in SLMC-QC post-vaccination of CoronaVac

Out of the 2954 CoronaVac vaccinees from SLMC, a total of 368 HCWs have been infected with SARS-CoV-2 after receiving either their first or second dose of CoronaVac vaccine from March to December 2021. 146 (4.94%) recipients have been infected with COVID-19 after receiving their first dose, while 222 (7.51%) participants tested positive for SARS-CoV-2 after completing two doses of the inactivated vaccine (Table 3).

Meanwhile, during the observation period after the 2nd dose of the vaccine, there were more reported cases of COVID-19. From a total of 222 (60.6%) COVID-19 confirmed cases after receiving their second dose of Sinovac, 33 were asymptomatic, while 176 recipients acquired mild infection and 12 participants had moderate COVID-19 infection. There was one case of severe COVID-19 and no cases of critical COVID-19 after completion of 2 doses among the HCWs (Figure 1).

Based on this information, the researchers have computed for the relative risk (RR) for acquiring COVID-19 (Table 9). In the unvaccinated group, the risk for COVID-19 infection was reported at 79.5%, while the computed risk for COVID-19 among the treatment group, or those who received CoronaVac, was at 12.5%. Moreover, the relative risk for COVID-19 infection when given SINOVAC vaccine was at 15%, with relative risk reduction (RRR) of 84.3% and an absolute risk reduction (ARR) 67% from baseline.

Conclusion

CoronaVac vaccine is clinically effective in reducing the risk and severity of COVID-19 infection among HCWs in the study institution. Likewise, this inactivated vaccine can be safely given to individuals who are eligible to receive COVID-19 vaccine.

Disclosures

All Authors: No reported disclosures.