Durability of ChAdOx1 nCoV-19 (AZD1222) vaccine and hybrid humoral immunity against variants including omicron BA.1 and BA.4 6 months after vaccination (COV005): a post-hoc analysis of a randomised, phase 1b-2a trial

BACKGROUND

COVID-19 vaccine rollout is lagging in Africa, where there has been a high rate of SARS-CoV-2 infection. We aimed to evaluate the effect of SARS-CoV-2 infection before vaccination with the ChAdOx-nCoV19 (AZD1222) vaccine on antibody responses through to 180 days.

METHODS

We did an unmasked post-hoc immunogenicity analysis after the first and second doses of AZD1222 in a randomised, placebo-controlled, phase 1b-2a study done in seven locations in South Africa. AZD1222 recipients who were HIV-uninfected, were stratified into baseline seropositive or seronegative groups using the serum anti-nucleocapsid (anti-N) immunoglobulin G (IgG) electroluminescence immunoassay to establish SARS-CoV-2 infection before the first dose of AZD1222. Binding IgG to spike (anti-S) and receptor binding domain (anti-RBD) were measured before the first dose (day 0), second dose (day 28), day 42, and day 180. Neutralising antibody (NAb) against SARS-CoV-2 variants D614G, beta, delta, gamma, and A.VOI.V2, and omicron BA1 and BA.4 variants, were measured by pseudovirus assay (day 28, day 42, and day 180). This trial is registered with ClinicalTrials.gov, NCT04444674, and the Pan African Clinicals Trials Registry, PACTR202006922165132.

FINDINGS

Of 185 individuals who were randomly assigned to AZD1222, we included 91 individuals who were baseline seropositive and 58 who were baseline seronegative, in the final analysis. In the seropositive group, there was little change of anti-S IgG (and anti-RBD IgG) or neutralising antibody (NAb) titres at day 42 compared with at day 28. Anti-S (and anti-RBD) IgG geometric mean concentrations (GMCs) were higher throughout in the seropositive compared with the seronegative group, including at day 180 (GMCs 517·8 [95% CI 411·3-651·9] vs 82·1 [55·2-122·3] BAU/mL). Also D614G NAb geometric mean titres (GMTs) were higher in the seropositive group than the seronegative group, as was the percentage with titres of at least 185 (80% putative risk reduction threshold [PRRT] against wild-type-alpha COVID-19), including at day 180 (92·0% [74·0-99·0] vs 18·2% [2·3-51·8). Similar findings were observed for beta, A.VOI.V2, and gamma. For delta, BA.1, and BA.4, NAb GMTs and the proportion with titres above the PRRT were substantially higher in the seropositive compared with seronegative group at day 28 and day 42, but no longer differed between the groups by day 180.

INTERPRETATION

A single dose of AZD1222 in the general African population, where COVID-19 vaccine coverage is low and SARS-CoV-2 seropositivity is 90%, could enhance the magnitude and quality of antibody responses to SARS-CoV-2.

FUNDING

The Bill & Melinda Gates Foundation, the South African Medical Research Council, the UK Research and Innovation, the UK National Institute for Health Research, and the South African Medical Research Council.

TRANSLATION

For the Zulu translation of the abstract see Supplementary Materials section.

Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B.1.351 Variant

BACKGROUND

Assessment of the safety and efficacy of vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different populations is essential, as is investigation of the efficacy of the vaccines 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 multicenter, double-blind, randomized, controlled trial to assess the safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) in people not infected with the human immunodeficiency virus (HIV) in South Africa. Participants 18 to less than 65 years of age were assigned in a 1:1 ratio to receive two doses of vaccine containing 5×1010 viral particles or placebo (0.9% sodium chloride solution) 21 to 35 days apart. Serum samples obtained from 25 participants after the second dose were tested by pseudovirus and live-virus neutralization assays against the original D614G virus and the B.1.351 variant. The primary end points were safety and efficacy of the vaccine against laboratory-confirmed symptomatic coronavirus 2019 illness (Covid-19) more than 14 days after the second dose.

RESULTS

Between June 24 and November 9, 2020, we enrolled 2026 HIV-negative adults (median age, 30 years); 1010 and 1011 participants received at least one dose of placebo or vaccine, respectively. Both the pseudovirus and the live-virus neutralization assays showed greater resistance to the B.1.351 variant in serum samples obtained from vaccine recipients than in samples from placebo recipients. In the primary end-point analysis, mild-to-moderate Covid-19 developed in 23 of 717 placebo recipients (3.2%) and in 19 of 750 vaccine recipients (2.5%), for an efficacy of 21.9% (95% confidence interval [CI], -49.9 to 59.8). Among the 42 participants with Covid-19, 39 cases (95.1% of 41 with sequencing data) were caused by the B.1.351 variant; vaccine efficacy against this variant, analyzed as a secondary end point, was 10.4% (95% CI, -76.8 to 54.8). The incidence of serious adverse events was balanced between the vaccine and placebo groups.

CONCLUSIONS

A two-dose regimen of the ChAdOx1 nCoV-19 vaccine did not show protection against mild-to-moderate Covid-19 due to the B.1.351 variant. (Funded by the Bill and Melinda Gates Foundation and others; ClinicalTrials.gov number, NCT04444674; Pan African Clinical Trials Registry number, PACTR202006922165132).

Dataset on discarded cigarette packs in Mongolia

This dataset documents the variety of discarded cigarette packs available in Mongolia, specifically in the capital city (Ulaanbaatar) and 2 provinces (Dornod and Bayan Ulgii). Both of these provinces border China and the Russian Federation. Discarded cigarette packs were collected from the ground or from the top of waste bins. Packs were collected over three rounds of data collection (round 1: April 2017, round 2: August/September 2017 and round 3: May/June 2018). 7494 packs were collected in round 1, 5852 packs in round 2 and 6258 packs in round 3. The dataset consists of 25 variables which describe each pack in detail, including information on excise tax stamps, health warnings, tar and nicotine levels, brand name, name of manufacturer, and importer, among others. This data is freely available on the DataFirst data repository (https://www.datafirst.uct.ac.za/dataportal/index.php/catalog/772) after creating a user profile. This data was used for a research article titled "The impact of tax increases on illicit cigarette trade in Mongolia" which was published by Tobacco Control in 2019 (https://tobaccocontrol.bmj.com/content/early/2019/06/18/tobaccocontrol-2018-054904). The paper is co-authored by Ross H, Vellios N, Batmunkh T, Enkhtsogt M and Rossouw L.

Access to human immunodeficiency virus testing services in Cape Town, South Africa: a user perspective

Objective: To compare the availability, affordability and acceptability of two non-governmental organisation (NGO) led human immunodeficiency virus (HIV) testing service (HTS) modalities (mobile and stand-alone) with HTS at a public primary health care facility. Methods: Adult participants who self-referred for HIV testing were enrolled as they exited the HTS modalities. Data collection using an electronic questionnaire took place between November 2014 and February 2015. Logistic regression analysis was used to assess differences in the participants' demographic characteristics and the availability, affordability and acceptability of HTS between modalities. Results: There were 130 participants included in the study. Irrespective of modality, most participants walked to the service provider, had a travel time of <30 min and reported no costs. Participants were less likely to report waiting times of ⩾30 min compared to <15 min at the mobile modality compared to the public facility (aOR < 0.001, 95%CI < 0.001-0.03). Conclusion: Irrespective of modality, HIV testing services were available and affordable in our study. Waiting times were significantly higher at the public facility compared to the NGO modalities. As South Africa moves toward achieving the first UNAIDS target, it is essential not only to make HTS available and affordable, but also to ensure that these services are acceptable, especially to those who have never been tested before.

The influence of baboon predation and time in water on germination and early establishment of Opuntia stricta (Australian pest pear) in the Kruger National Park

The alien invader weed, Opuntia stricta Haw (family Cactaceae), is seriously threatening biodiversity in veld habitats of the Kruger National Park. Basic biological and ecological information on the establishment, growth and reproduction of the species is necessary for the development of effective strategies for its control. The rapid spread of the plant is apparently mainly due to seed dispersal by baboon (Papio ursinus). Sixty percent of seed taken from baboon faeces resulted in seedlings that established. Although palatability criteria for ripe fruit were more favourable than for unripe or medium-ripe fruit, seed from fruit at all three degrees of ripeness germinated equally well, and seedling establishment was similar. Despite their lower acidity, as well as higher total soluble sugar content and pH, cladodes are not subject to herbivory to near the extent that ripe fruit are. Freshly collected seed kept in Sabie River water showed significantly better germination/emergence after seven days submersion (83 ) than at 14 or 28 days (52 and 66 , respectively). Results suggest that seed dispersal of the species by animals, principally baboon, is an important cause of rapidly expanding infestations, and that dissipation in water will intensify the problem. Current findings should contribute toward the development of long-term weed management strategies aimed at con- tainment/eradication of the weed.

The unbooked mother at Tygerberg Hospital. A prospective controlled study

A prospective controlled study was carried out at Tygerberg Hospital to ascertain the difference between booked and unbooked mothers with regard to social and medical aspects and knowledge of the medical system. Thirty unbooked mothers were compared with 77 booked mothers. The general picture that emerged was that the unbooked mother is young, unmarried and unemployed, has a low income and has no permanent relationship with the father of the infant. However, she knows where the antenatal clinic is and that she should and when she should attend. The reasons for not attending were non-specific. There was no difference between the two groups as regards level of education. The obstetric complications in the unbooked group were premature labour, premature rupture of the membranes and intra-uterine death. These did not occur in the control group. It is suggested that an important difference between booked and unbooked patients is personality and attitude towards pregnancy and parenthood.