Seroconversion Rates of Inactive COVID-19 Vaccine CoronaVac in Healthcare Workers

Erdinç Yavuz, Özgür Günal, Eşe Başbulut, Ahmet Şen

Keywords: COVID-19, seroconversion, healthcare worker

Aim:

The effectiveness of Sinovac's Coronavac vaccine to induce humoral immunity was evaluated with a study conducted at Samsun Training and Research Hospital.

Method:

The participants were divided into two groups as those who had COVID-19 confirmed with a positive RT-PCR test and those who did not have a history of COVID 19 or previous antibody positivity. Serum Ig G antibody titers against SARS-Cov-2 virus spike protein's "Receptor Binding Domain (RBD)" were investigated in blood samples taken 14 and 28 days after the first dose of vaccine.

Results:

The first group consisted of 90 HCWs (42 male; and 48 women) who did not have a history of COVID-19 and SARS-CoV-2 antibody positivity before. Mean age in this group was calculated as 41.3±8,34 years (Min: 26, Max: 62 years). 14 days after the first dose of vaccine, 32 (35.5%) of the participants were found to have a positive antibody titer. This number increased to 59 (65.5%) and antibody titers increased in 84 (93.3%) participants at day 28. Mean antibody titers were 94.5 AU/ml at day 14 and 145.5 AU/ml at day 28. There were 12 men and 17 women in the second group of 29 HCWs, who were shown to be tested positive for COVID-19 in the last four months. Mean age was calculated as 41.4±8,14 years (Min: 26 max: 66 years). 14 days after the first dose of vaccine, 25 (86.2%) of the participants were found to have a positive antibody titer. 28 days after the first dose of vaccine this number increased to 27 (93.1%). An increase in antibody titers was shown in 18 HCWs (62%). Mean antibody titers were 1382.7 AU/ml on day 14 and 1441.3 AU/ml on day 28.

Conclusions:

These results have shown that even with a single dose, CoronaVac induced humoral immnunity in majority of the participants.

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