SARS-CoV-2 infection is at herd immunity in the majority segment of the population of Qatar

Al-Thani, Mohamed H; Farag, Elmoubasher; Bertollini, Roberto; Al Romaihi, Hamad Eid; Abdeen, Sami; Abdelkarim, Ashraf; Daraan, Faisal; Ismail, Ahmed; Mostafa, Nahid; Sahl, Mohamed; Suliman, Jinan; Tayar, Elias; Kasem, Hasan Ali; Agsalog, Meynard J A; Akkarathodiyil, Bassam K; Alkhalaf, Ayat A; Alakshar, Mohamed Morhaf M H; Al-Qahtani, Abdulsalam Ali A H; Al-Shedifat, Monther H A; Ansari, Anas; Ataalla, Ahmad Ali; Chougule, Sandeep; Gopinathan, Abhilash K K V; Poolakundan, Feroz J; Ranbhise, Sanjay U; Saefan, Saed M A; Thaivalappil, Mohamed M; Thoyalil, Abubacker S; Umar, Inayath M; Al Kanaani, Zaina; Al Khal, Abdullatif; Al Kuwari, Einas; Butt, Adeel A; Coyle, Peter; Jeremijenko, Andrew; Kaleeckal, Anvar Hassan; Latif, Ali Nizar; Shaik, Riyazuddin Mohammad; Abdul Rahim, Hanan F; Yassine, Hadi M; Nasrallah, Gheyath K; Al Kuwari, Mohamed Ghaith; Chaghoury, Odette; Chemaitelly, Hiam; Abu-Raddad, Laith J

BACKGROUND: Qatar experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic that disproportionately affected the craft and manual worker (CMW) population who comprise 60% of the total population. This study aimed to assess ever and/or current infection prevalence in this population. METHODS: A cross-sectional population-based survey was conducted during July 26-September 09, 2020 to assess both anti-SARS-CoV-2 positivity through serological testing and current infection positivity through polymerase chain reaction (PCR) testing. Associations with antibody and PCR positivity were identified through regression analyses. RESULTS: Study included 2,641 participants, 69.3% of whom were <40 years of age. Anti-SARS-CoV-2 positivity was 55.3% (95% CI: 53.3-57.3%) and was significantly associated with nationality, geographic location, educational attainment, occupation, and previous infection diagnosis. PCR positivity was 11.3% (95% CI: 9.9-12.8%) and was significantly associated with nationality, geographic location, occupation, contact with an infected person, and reporting two or more symptoms. Infection positivity (antibody and/or PCR positive) was 60.6% (95% CI: 58.6-62.5%). The proportion of antibody-positive CMWs that had a prior SARS-CoV-2 diagnosis was 9.3% (95% CI: 7.9-11.0%). Only seven infections were ever severe and one was ever critical—an infection severity rate of 0.5% (95% CI: 0.2-1.0%). CONCLUSIONS: Six in every 10 CMWs have been infected, suggestive of reaching the herd immunity threshold. Infection severity was low with only one in every 200 infections progressing to be severe or critical. Only one in every 10 infections had been previously diagnosed suggestive of mostly asymptomatic or mild infections.