Efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2 lineages circulating in Brazil
Clemens SAC., Folegatti PM., Emary KRW., Weckx LY., Ratcliff J., Bibi S., De Almeida Mendes AV., Milan EP., Pittella A., Schwarzbold AV., Sprinz E., Aley PK., Bonsall D., Fraser C., Fuskova M., Gilbert SC., Jenkin D., Kelly S., Kerridge S., Lambe T., Marchevsky NG., Mujadidi YF., Plested E., Ramasamy MN., Simmonds P., Golubchik T., Voysey M., Pollard AJ., Buck D., Green A., MacIntyre-Cockett G., Piazza P., Todd JA., Trebes A., Thomson L., Tinoco LA., Ferreira KCMA., Almeida C., Angus B., Arns B., Arruda L., De Ávila Kfouri R., da Silva LHA., Moreira MJB., Paiva BVB., Bates L., Bellei N., Boettger B., Lora LB., de Araújo NAB., de Oliveira CDNB., Brown-O’Sullivan C., Luz DC., Mourão JRC., Carvalho CS., Cicconi P., Cruz AG., Cunha D., Da Costa DM., Da Silva Gonzalez IG., de Arruda Trindade P., de Freitas Souza BS., De Jesus Junior SCA., de Moraes Pinto MI., De Mores KP., de Nobrega MM., Sampaio MD., dos Santos JKD., Douglas AD., da Guarda SNF., Farooq MG., Feng S., dos Santos MCF., Franco MM., de Oliveira MG., Spina FG., dos Santos TG., Goyanna AH., Haddad RE., Hill AVS., Hou MM., Junqueira B., Kelling BS., Khozoee B., Kunst RG., Kwok J., Madhavan M., de Carvalho JAM., Mazur O., Minassian AM., Ramos LM., Myasaki CH., Noal HC., de Lima NN., Noristani R., Perez AL., Phillips DJ., Pinheiro P., Pinheiro JMG., Camara MMP.
Several COVID-19 vaccines have shown good efficacy in clinical trials, but there remains uncertainty about the efficacy of vaccines against different variants. Here, we investigate the efficacy of ChAdOx1 nCoV-19 (AZD1222) against symptomatic COVID-19 in a post-hoc exploratory analysis of a Phase 3 randomised trial in Brazil (trial registration ISRCTN89951424). Nose and throat swabs were tested by PCR in symptomatic participants. Sequencing and genotyping of swabs were performed to determine the lineages of SARS-CoV-2 circulating during the study. Protection against any symptomatic COVID-19 caused by the Zeta (P.2) variant was assessed in 153 cases with vaccine efficacy (VE) of 69% (95% CI 55, 78). 49 cases of B.1.1.28 occurred and VE was 73% (46, 86). The Gamma (P.1) variant arose later in the trial and fewer cases (N = 18) were available for analysis. VE was 64% (−2, 87). ChAdOx1 nCoV-19 provided 95% protection (95% CI 61%, 99%) against hospitalisation due to COVID-19. In summary, we report that ChAdOx1 nCoV-19 protects against emerging variants in Brazil despite the presence of the spike protein mutation E484K.