Abu-Raddad LJ, Chemaitelly H, Ayoub HH, et al. - In order to ascertain the consequences of the introduction of a novel SARS-CoV-2 variant emerged in the United Kingdom, B.1.1.7 (known also as Alpha), into a new national population, researchers herein examined the introduction and expansion of this variant in Qatar as well as determined efficacy of natural infection against reinfection with this variant.

• Two national retrospective cohort studies (a national cohort of 159,003 individuals with prior PCR-confirmed infections and a national cohort of 43,127 antibody-positive individuals), mathematical modeling, and other statistical analyses, were used to determine the epidemiology of B.1.1.7 and to answer the study’s research questions.

• Shortly after introduction of this variant, a sudden, large, and rapidly growing epidemic wave of B.1.1.7 cases began in Qatar.

• As per findings, B.1.1.7 was nearly 60% more infectious than the original wild-type circulating variants.

• The natural infection with B.1.1.7 had efficacy against reinfection at 97.5% (95% CI: 95.7% to 98.6%) among those with a prior PCR-confirmed infection and at 97.0% (95% CI: 92.5% to 98.7%) among those with a prior antibody-positive result.

• Overall, this study indicate that introduction of B.1.1.7 into a naïve population can lead to a major epidemic wave, however, there was strong correlation of natural immunity in those previously infected with limited incidence of reinfection by B.1.1.7 or other variants.