LAUSR

Due to the recent coronavirus disease 2019 (COVID‐19) pandemic and emergent administration of various vaccines worldwide, comprehensive studies on the different aspects of vaccines are in demand. This study evaluated antibody response after the second dose of the COVID‐19 vaccine in the Children's Medical Center personnel. The blood samples of 174 healthcare workers were gathered at least 10 days after vaccination. The administered vaccines included Oxford/AstraZeneca, COVAXIN, Sinopharm, and Sputnik V. This study assessed all antibodies employing ELISA methods, including anti‐SARS‐CoV‐2 neutralizing antibody by DiaZist and Pishtazteb kits, anti‐SARS‐CoV‐2‐nucleocapsid by Pishtazteb kit, and anti‐SARS‐CoV‐2‐Spike by Razi kit. The cutoff for the tests' results was calculated according to the instructions of each kit. Totally, 174 individuals with an average age of 40 ± 9 years participated in this study, the proportion of men was 31%, and the frequency of past COVID‐19 infection was 66 (38%). Sixteen (9%) personnel received Oxford/AstraZeneca, 28 (16%) COVAXIN, 29 (17%) Sinopharm, and 101 (58%) Sputnik V. anti‐SARS‐CoV‐2‐nucleocapsid and anti‐SARS‐CoV‐2‐Spike were positive in 37 (21%), and 163 (94%) participants and their mean level were more in adenoviral‐vectored vaccines (p value < 0.0001). Neutralizing antibody was positive in 74% using Pishtazteb kit while 87% using DiaZist kit. All antibodies' levels were significantly higher in those with a past COVID‐19 infection (p value < 0.0001). In conclusion, Oxford/AstraZeneca and Sputnik V had a similar outcome of inducing high levels of anti‐SARS‐Cov‐2‐spike and neutralizing antibodies, which were more than Sinopharm and COVAXIN. The titers of Anti‐SARS‐CoV‐2‐nucleocapsid antibody were low in all of these four vaccines.