Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Dec 16;18(12):e1003879.
doi: 10.1371/journal.pmed.1003879. eCollection 2021 Dec.

Introduction and expansion of the SARS-CoV-2 B.1.1.7 variant and reinfections in Qatar: A nationally representative cohort study

Laith J Abu-Raddad  1   2   3 , Hiam Chemaitelly  1   2 , Houssein H Ayoub  4 , Peter Coyle  5   6   7 , Joel A Malek  8   9 , Ayeda A Ahmed  8 , Yasmin A Mohamoud  8 , Shameem Younuskunju  8 , Patrick Tang  10 , Zaina Al Kanaani  5 , Einas Al Kuwari  5 , Adeel A Butt  3   5 , Andrew Jeremijenko  5 , Anvar Hassan Kaleeckal  5 , Ali Nizar Latif  5 , Riyazuddin Mohammad Shaik  5 , Hanan F Abdul Rahim  11 , Gheyath K Nasrallah  6   12 , Hadi M Yassine  6   12 , Mohamed Ghaith Al Kuwari  13 , Hamad Eid Al Romaihi  14 , Mohamed H Al-Thani  14 , Abdullatif Al Khal  5 , Roberto Bertollini  14
Affiliations

Introduction and expansion of the SARS-CoV-2 B.1.1.7 variant and reinfections in Qatar: A nationally representative cohort study

Laith J Abu-Raddad et al. PLoS Med. .

Abstract

Background: The epidemiology of the SARS-CoV-2 B.1.1.7 (or Alpha) variant is insufficiently understood. This study's objective was to describe the introduction and expansion of this variant in Qatar and to estimate the efficacy of natural infection against reinfection with this variant.

Methods and findings: Reinfections with the B.1.1.7 variant and variants of unknown status were investigated in a national cohort of 158,608 individuals with prior PCR-confirmed infections and a national cohort of 42,848 antibody-positive individuals. Infections with B.1.1.7 and variants of unknown status were also investigated in a national comparator cohort of 132,701 antibody-negative individuals. B.1.1.7 was first identified in Qatar on 25 December 2020. Sudden, large B.1.1.7 epidemic expansion was observed starting on 18 January 2021, triggering the onset of epidemic's second wave, 7 months after the first wave. B.1.1.7 was about 60% more infectious than the original (wild-type) circulating variants. Among persons with a prior PCR-confirmed infection, the efficacy of natural infection against reinfection was estimated to be 97.5% (95% CI: 95.7% to 98.6%) for B.1.1.7 and 92.2% (95% CI: 90.6% to 93.5%) for variants of unknown status. Among antibody-positive persons, the efficacy of natural infection against reinfection was estimated to be 97.0% (95% CI: 92.5% to 98.7%) for B.1.1.7 and 94.2% (95% CI: 91.8% to 96.0%) for variants of unknown status. A main limitation of this study is assessment of reinfections based on documented PCR-confirmed reinfections, but other reinfections could have occurred and gone undocumented.

Conclusions: In this study, we observed that introduction of B.1.1.7 into a naïve population can create a major epidemic wave, but natural immunity in those previously infected was strongly associated with limited incidence of reinfection by B.1.1.7 or other variants.

PubMed Disclaimer

Conflict of interest statement

I have read the journal’s policy and the authors of this manuscript have the following competing interests: A.A.B. has received institutional grant funding from Gilead Sciences unrelated to the work presented in this paper, otherwise, the authors declare no competing interests.

Figures

Fig 1
Fig 1. SARS-CoV-2 B.1.1.7 variant expansion in Qatar.
(A) Time series of the number of new B.1.1.7 cases. (B) Percentage of new B.1.1.7 variant cases among all PCR-confirmed cases.
Fig 2
Fig 2. Estimated effective reproduction number (Rt) for SARS-CoV-2 infection.
(A) All circulating variants. (B) Only B.1.1.7. Rt was calculated using the Robert Koch Institute method [37].
Fig 3
Fig 3. Flow chart of SARS-CoV-2 reinfections with B.1.1.7 and variants of unknown status in the national cohort of individuals with prior PCR-confirmed infections.
Fig 4
Fig 4. Flow chart of SARS-CoV-2 reinfections with B.1.1.7 and variants of unknown status in the national cohort of antibody-positive individuals and the national cohort of antibody-negative individuals.
(A) Antibody-positive individuals. (B) Antibody-negative individuals.
See this image and copyright information in PMC

References

    1. Abu-Raddad LJ, Chemaitelly H, Ayoub HH, Al Kanaani Z, Al Khal A, Al Kuwari E, et al.. Characterizing the Qatar advanced-phase SARS-CoV-2 epidemic. Sci Rep. 2021;11(1):6233. doi: 10.1038/s41598-021-85428-7 - DOI - PMC - PubMed
    1. Ayoub HH, Chemaitelly H, Seedat S, Makhoul M, Al Kanaani Z, Al Khal A, et al.. Mathematical modeling of the SARS-CoV-2 epidemic in Qatar and its impact on the national response to COVID-19. J Glob Health. 2021;11:05005. doi: 10.7189/jogh.11.05005 - DOI - PMC - PubMed
    1. Al Kuwari HM, Abdul Rahim HF, Abu-Raddad LJ, Abou-Samra AB, Al Kanaani Z, Al Khal A, et al.. Epidemiological investigation of the first 5685 cases of SARS-CoV-2 infection in Qatar, 28 February–18 April 2020. BMJ Open. 2020;10(10):e040428. doi: 10.1136/bmjopen-2020-040428 - DOI - PMC - PubMed
    1. Bsat R, Chemaitelly H, Coyle P, Tang P, Hasan MR, Al Kanaani Z, et al.. Characterizing the effective reproduction number during the COVID-19 epidemic: insights from Qatar’s experience. medRxiv. 2021. Oct 7. doi: 10.1101/2021.10.07.21264599 - DOI - PMC - PubMed
    1. Polack FP, Thomas SJ, Kitchin N, Absalon J, Gurtman A, Lockhart S, et al.. Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. N Engl J Med. 2020;383(27):2603–15. doi: 10.1056/NEJMoa2034577 - DOI - PMC - PubMed

Publication types

MeSH terms

Supplementary concepts