Herd Immunity against Severe Acute Respiratory Syndrome Coronavirus 2 Infection in 10 Communities, Qatar

Jeremijenko, Andrew; Chemaitelly, Hiam; Ayoub, Houssein H.; Alishaq, Moza; Abou-Samra, Abdul-Badi; Al Ajmi, Jameela Ali A.A.; Al Ansari, Nasser Ali Asad; Al Kanaani, Zaina; Al Khal, Abdullatif; Al Kuwari, Einas; Al-Mohammed, Ahmed; Al Molawi, Naema Hassan Abdulla; Al Naomi, Huda Mohamad; Butt, Adeel A.; Coyle, Peter; El Kahlout, Reham Awni; Gillani, Imtiaz; Kaleeckal, Anvar Hassan; Masoodi, Naseer Ahmad; Thomas, Anil George; Nafady-Hego, Hanaa; Latif, Ali Nizar; Shaik, Riyazuddin Mohammad; Younes, Nourah B.M.; Rahim, Hanan F. Abdul; Yassine, Hadi M.; Al Kuwari, Mohamed G.; Al Romaihi, Hamad Eid; Al-Thani, Mohamed H.; Bertollini, Roberto; Abu-Raddad, Laith J.

We investigated what proportion of the population acquired severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and whether the herd immunity threshold has been reached in 10 communities in Qatar. The study included 4,970 participants during June 21–September 9, 2020. Antibodies against SARS-CoV-2 were detected by using an electrochemiluminescence immunoassay. Seropositivity ranged from 54.9% (95% CI 50.2%–59.4%) to 83.8% (95% CI 79.1%–87.7%) across communities and showed a pooled mean of 66.1% (95% CI 61.5%–70.6%). A range of other epidemiologic measures indicated that active infection is rare, with limited if any sustainable infection transmission for clusters to occur. Only 5 infections were ever severe and 1 was critical in these young communities; infection severity rate of 0.2% (95% CI 0.1%–0.4%). Specific communities in Qatar have or nearly reached herd immunity for SARS-CoV-2 infection: 65%–70% of the population has been infected.