SARS-COV-2 antibody seroprevalence in the general population of Oman: results from four successive nationwide seroepidemiological surveys

Al-Abri, Seif Salem; Al-Wahaibi, Adel; Al-Kindi, Hanan; Kurup, Padmamohan J; Al-Maqbali, Ali; Al-Mayahi, Zayid; Al-Tobi, Mohammed Hamed; Al-Katheri, Salim Habbash; Albusaidi, Sultan; Al-Sukaiti, Mahmood Humaid; Al Balushi, Ahmed Yar Mohammed; Abdelgadir, Iyad Omer; Al-Shehi, Nawal; Morkos, Essam; Al-Maani, Amal; Al-Rawahi, Bader; Alyaquobi, Fatma; Alqayoudhi, Abdullah; Al-Harthy, Khalid; Al-Khalili, Sulien; Al-Rashdi, Azza; Al-Shukri, Intisar; Al Ghafri, Thamra S; Al-Hashmi, Fatma; Al Jassasi, Saeed Mussalam; Alshaqsi, Nasser; Mitra, Nilanjan; Al Aamry, Humaid Suhail; Shah, Parag; Al Marbouai, Hanan Hassan; Al Araimi, Amany Hamed; Kair, Ismail Mohammed; Al Manji, Asim Mohammed; Almallak, Ahmed Said; Al Alawi, Fatma Khamis; Vaidya, Vidyanand; Muqeetullah, Muhammad; alrashdi, Hanan; Al Jamoudi, Saud Said Nassir; Alshaqsi, Asila; Al Sharji, Abdullah; Al Shukeiri, Hamida; Al-Abri, Badr; Al-Rawahi, Sulaiman; Al-Lamki, Said H; Al-Manji, Abdulla; Al-Jardani, Amina

Objective To assess SARS-COV-2 seroprevalence in Oman and longitudinal changes in antibody levels over time within the first 11 months of the COVID-19 pandemic. Methods This nationwide cross-sectional study was conducted as a four-cycle serosurvey using a multistage stratified sampling method from July–November 2020. A questionnaire was used and included demographics, history of acute respiratory infection and list of symptoms, COVID-19 contact, previous diagnosis or admission, travel history, and risk factors. Results In total, 17,457 participants were surveyed. Thirty percent were female, and 66.3% Omani. There was significant increase in seroprevalence throughout the study cycles, starting from [5.5 (4.8–6.2)] for the first cycle and ending with [22 (19.6–24.6)] for the forth cycle. There was no difference in seroprevalence between genders, but significant differences between age groups. There was a transition of seroprevalence from being higher in non-Omanis in cycle one, [9.1 (7.6–10.9)] to Omanis [3.2 (2.6–3.9)] to being higher in Omanis [24.3 (21.0–27.9)] to non-Omanis [16.8 (14.9–18.9)] in cycle four. There was remarkable variation in seroprevalence of COVID-19 according to governorate. Close contacts of people with COVID-19 had a 96% higher risk of having the disease, (adjusted odds ratio [AOR]=1.96, 95% confidence interval [CI] 1.64–2.34); laborers have 58% higher risk of infection compared to office workers (AOR=1.58, 95% CI; 1.04–2.35). Conclusion The study showed a wide variation of SARS-CoV-2 dissemination between governorates in Oman, with higher seroprevalence estimates in migrants in the first two cycles. Prevalence estimates remain low and are insufficient to provide herd immunity.