Résumé
Background: SARS-CoV-2 is a novel virus that caused the recent global pandemic. Health care workers (HCWs), especially hospital staff, are at a higher risk of infection by this virus than the general population. In this study, anti-SARS-CoV-2 IgG antibodies were assessed in hospital workers. Methods: This prospective seroconversion-based cohort study assessed chronic immunity against covid-19 in the staff of two hos-pitals, the main referral hospital and a general hospital in Shiraz, south of Iran. A valid and reliable checklist was filled out for each available staff member willing to participate in this study through a face-to-face interview. Furthermore, the titer of anti-covid-19 IgG was measured by ELISA twice;in July 2020 after the second wave of COVID-19 and in February 2021 after the third wave in IRAN. Results: One hundred forty (65%) of the 214 members who participated in both stages of this consideration were from the COVID-19 referral healing center, and 74 (35%) were from the common clinic. Twelve (5.6%) of staff members had anti-SARS-CoV-2 IgG anti-bodies, including 10 (7.1%) from the referral healing center and 2 (2.7%) from the common healing center (P = 0.23). In the second measurement (second overview), 79 (36.9%) of members had IgG antibodies;58 (41.4%) from the primary hospital and 21 (28.3%) from the second healing center (P = 0.039). Cruel of the IgG titer within the first study and the referral clinic was 0.8 ± 0.3 compared to 0.15 ± 0.42 within the common clinic (P = 0.001). These figures were 3.05 ± 4.58 and 1.74 ± 3.53 in both clinics and within the second overview separately (P = 0.003). IgG levels were significantly higher in the second overview compared to the first (P < 0.0001). Conclusions: During the third wave of COVID-19, a significant proportion of hospital staff developed COVID-19 IgG, especially in the referral hospitals for COVID-19. As a result of their higher and chronic exposure to COVID-19 patients than the general hospital staff, the titer of IgG in the referral hospital staff was also higher. However, the seroconversion rate between the two waves was 1.8 times in the general hospital staff compared to the referral hospital, possibly due to less conservative precautions against covid-19 among them. Even after receiving the anti-covid-19 vaccination, it is important to monitor the immunity of hospital staff to covid-19 and to adhere strictly to standard precautions.