SARS-CoV-2 Infection Is at Herd Immunity in the Majority Segment of the Population of Qatar
Authors: Al-Thani Mohamed H , Farag Elmoubasher , Bertollini Roberto , Al Romaihi Hamad Eid , Abdeen Sami , Abdelkarim Ashraf , Daraan Faisal , Elhaj Ismail Ahmed Ibrahim Hashim , 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 ,   Craft and Manual Workers Seroprevalence Study Group, Aerattel Shafeer T , Ansari Firoj , Babu Bennet J , Bakari Ali O , Basheer Fazil K , Cherikkal Muhammed J , Chonari Muhammed R , Darwish Ahmad S , Cruz Arvin Dela , Dela Cruz Verlili Z , Del Carmen Mark W , Deomampo Richie P , Gopi Sanu , Hortaleza Delfin J R O , Joseph Robin , Kadar Veerankutty , Kalathil Abdul Kareem A , Kandi Bigil C , Kaniyankandi Mohammed M T , Karimparukuzhiyil Kamarudheen , Kurane Deelip G , Kurungott Manu , Lumibao Jommel R C , Mahmoud Walid , Malik Reyaz A , Maxino Jan A , Moosakutty Nabeel T , Nawabjahn Hameed N , Orio Ryan E , Osman Mohamed F , Ottappilakkool Muhammad H , Pattakunninmel Vijayakumar , Peedika Nissar P , Puthiyaveettil Suhail T , Raghavan Ajith , Ramachandran Renjee , Sainudheen Adil S , Sassendran Kannan , Soosai John M M , Sseri Harris P , Vallapil Deepu , Venzuela Patrick J S , Abdoon Rana A M , Ahmed Hind S M , Mahmoud Ayah M A , Gismelkhalig Omnia O E , Shihata Farid , Ali Khaled M , Alsallama Fraih A A F 
Published: May 2021

Abstract

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 to 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
The study included 2641 participants, 69.3% of whom were &lt;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 2 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 who had a prior SARS-CoV-2 diagnosis was 9.3% (95% CI, 7.9%–11.0%). Only seven infections were ever severe, and only 1 was ever critical—an infection severity rate of 0.5% (95% CI, 0.2%–1.0%).

Conclusions
Six in every 10 CMWs in Qatar have been infected, suggestive of reaching the herd immunity threshold. Infection severity was low, with only 1 in every 200 infections progressing to be severe or critical. Only 1 in every 10 infections had been previously diagnosed, which is suggestive of mostly asymptomatic or mild infections.