Publication

Title: Safety and efficacy of the ChAdOx1 nCoV-19 (AZD1222) Covid-19 vaccine against the B.1.351 variant in South Africa
Authors: Madhi SA, Baillie VL, Cutland CL, Voysey M, KoenAL, Fairlie L, Padayachee SD, Dheda K, Barnabas SL, Bhorat QE, Briner C, Kwatra G, Ahmed K, Aley P, Bhikha S, Bhiman JN, Bhorat AE, du plessis J, Esmail A, Groenewald M, Horne E, Hwa S-H, Jose A, Lambe T, Laubscher M, Malahleha M, Masenya M, Masilela M, McKenzie S, Molapo K, Moultrie A, Oelofse S, Pate Fl, Pillay S, Rhead S, Rodel H, Rossouw L, Taoushanis C, Tegally H, Thombrayil A, van Eck S, Wibmer C, Durham NM, Kelly EJ, Villafana T, Gilbert S, Pollard AJ, de Oliveira T, Moore PL, Sigal A, Izu A, NGS-SA, Wits VIDA COVID vaccine trial group .
Journal: medRxiv,https://doi.org/10.1101/2021.02.10.21251247: (2021)

Abstract

<Background Assessing safety and efficacy of Covid-19 vaccines in different populations is essential, as is investigation of efficacy against emerging SARS-CoV-2 variants of concern including the B.1.351 (501Y.V2) variant first identified in South Africa.

Methods We conducted a randomized multicentre, double blinded controlled trial on safety and efficacy of ChAdOx1-nCoV19 in HIV-uninfected people in South Africa. Participants age 18 to <65 years randomized (1:1) to two doses of vaccine containing 5x1010 viral particles or placebo (0.9%NaCl) 21-35 days apart. Post 2nd-dose serum samples (n=25) were tested by pseudotyped (PSVNA) and live virus (LVNA) neutralization assays against the D614G and B.1.351 variants. Primary endpoints were safety and vaccine efficacy (VE) >14 days following second dose against laboratory confirmed symptomatic Covid-19.

Results 2026 HIV-uninfected adults were enrolled between June 24th and Nov 9th, 2020; 1010 and 1011 received at least one dose of placebo or vaccine, respectively. Median age was 31 years. The B.1.351 variant showed increased resistance to vaccinee sera using the PSVNA and LVNA. In the primary endpoint analysis, 23/717 (3.2%) placebo and 19/750 (2.5%) vaccine recipients developed mild-moderate Covid-19; VE 21.9% (95%Confidence Interval: -49.9; 59.8). Of the primary endpoint cases, 39/42 (92.9%) were the B.1.351 variant; against which VE was 10.4% (95%CI: -76.8; 54.8) analyzed as a secondary objective. The incidence of serious adverse events was balanced between the vaccine and placebo groups.

Conclusions A two-dose regimen of ChAdOx1-nCoV19 did not show protection against mild-moderate Covid-19 due to B.1.351 variant, however, VE against severe Covid-19 is undetermined. (Funded by The Bill & Melinda Gates Foundation and South African Medical Research Council; ClinicalTrails.gov number, NCT04444674).

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Citation: Madhi SA, Baillie VL, Cutland CL, Voysey M, KoenAL, Fairlie L, Padayachee SD, Dheda K, Barnabas SL, Bhorat QE, Briner C, Kwatra G, Ahmed K, Aley P, Bhikha S, Bhiman JN, Bhorat AE, du plessis J, Esmail A, Groenewald M, Horne E, Hwa S-H, Jose A, Lambe T, Laubscher M, Malahleha M, Masenya M, Masilela M, McKenzie S, Molapo K, Moultrie A, Oelofse S, Pate Fl, Pillay S, Rhead S, Rodel H, Rossouw L, Taoushanis C, Tegally H, Thombrayil A, van Eck S, Wibmer C, Durham NM, Kelly EJ, Villafana T, Gilbert S, Pollard AJ, de Oliveira T, Moore PL, Sigal A, Izu A, NGS-SA, Wits VIDA COVID vaccine trial group . Safety and efficacy of the ChAdOx1 nCoV-19 (AZD1222) Covid-19 vaccine against the B.1.351 variant in South Africa medRxiv,https://doi.org/10.1101/2021.02.10.21251247: (2021).

Media Coverage of this Publication:


South African scientists on pandemic’s frontline - Financial Times - 2021-02-15

South Africa’s pause of its rollout of the Oxford/AstraZeneca vaccine in response to concern about a local coronavirus variant sparked global debate —and shone a spotlight on how the country’s science has become vital to understanding where the pandemic may go next.



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