SARS-CoV-2 seroconversion among 4040 Egyptian healthcare workers in 12 resource-limited healthcare facilities: A prospective cohort study
Aya Mostafa, Sahar Kandil, Manal H. El‐Sayed, Samia A. Girgis, Hala Hafez, Mostafa Yosef, Saly Saber, Hoda Ezzelarab, Marwa Ramadan, Eman Algohary, Gehan M. Fahmy, Iman Afifi, Fatmaelzahra Hassan, Shaimaa Elsayed, Amira Reda, Doaa Fattuh, Asmaa A. Mahmoud, Amany Mansour, Moshira Halim Sabry, Petra Habeb, Fatma Soliman Elsayed Ebeid, Ali Mohamed El-Anwar, Ayman Saleh, Ossama Mansour, Ashraf Omar, Mahmoud El‐Meteini
Abstract
BACKGROUND: We examined Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) seroconversion incidence and risk factors 21 days after baseline screening among healthcare workers (HCWs) in a resource-limited setting. METHODS: A prospective cohort study of 4040 HCWs took place at 12 university healthcare facilities in Cairo, Egypt; April-June 2020. Follow-up exposure and clinical data were collected through online survey. SARS-CoV-2 testing was done using rapid IgM and IgG serological tests and reverse transcriptase-polymerase chain reaction (RT-PCR) for those with positive serology. Cox proportional hazards modelling was used to estimate adjusted hazard ratios (HR) of seroconversion. RESULTS: 3870/4040 (95.8%) HCWs tested negative for IgM, IgG and PCR at baseline; 2282 (59.0%) returned for 21-day follow-up. Seroconversion incidence (positive IgM and/or IgG) was 100/2282 (4.4%, 95% CI:3.6-5.3), majority asymptomatic (64.0%); daily hazard of 0.21% (95% CI:0.17-0.25)/48 746 person-days of follow-up. Seroconversion was: 4.0% (64/1596; 95% CI:3.1-5.1) among asymptomatic; 5.3% (36/686; 95% CI:3.7-7.2) among symptomatic HCWs. Seroconversion was independently associated with older age; lower education; contact with a confirmed case >15 min; chronic kidney disease; pregnancy; change/loss of smell; and negatively associated with workplace contact. CONCLUSIONS: Most seroconversions were asymptomatic, emphasizing need for regular universal testing. Seropositivity was three-fold that observed at baseline. Cumulative infections increased nationally by a similar rate, suggesting HCW infections reflect community not nosocomial transmission.