ChAdOx1 nCoV-19 Vaccine and B.1.351 Variant of Concern, NCHEALTHEQ Submission to FDA
Updated: Jul 20, 2021
We previously reported that vaccines developed from adenovirus isolate Y25-derived vectors, such as ChAdOx1, were not optimal for global distribution and immunization against COVID-19. Our commentary was submitted to FDA (CBER) December 7, 2020, and based on the analysis presented in Nature concerning existing anti-vector immunity among a significant (9%) portion of a Gambian cohort compared with Anglo/White cohorts. Notably, ChAdOx1 is utilized in AZD1222 and related CTs by AstraZeneca PLC (AZN).
ChAdOx1 is a replication-deficient simian adenoviral vector derived from isolate Y25. This vector was chosen because of relatively low seroprevalence of human antibodies against Y25. However, existing anti-vector (Y25-derived) immunity among the Gambian cohort (9%),reported by van Doremalen et al. in Nature, may result in decreased efficacy of AZD1222 and poses serious ethical considerations about development intended for global distribution, with documented lower efficacy for a specific ethnic population. Moreover, the incidence of exceptionally rare thrombotic events is statistically overrepresented by ChAdOx1 derivatives, reported among 11 patients in Germany and Austria (Greinacher et al., 2021). It is important to note that severe adverse events are extremely rare, and vaccines distributed under Emergency Use Authorization in the United States have an exceptionally low incidence of adverse reactions, indicating EUA distributed vaccines are very safe.
What's Newly Learned
Recently, Madhi et al. (2021) reported in New England Journal of Medicine that 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.".
NCHEALTHEQ Advocates for Equity in Efficacy, Access, and Distribution
"It has been documented that Gambians have pre-existing anti-vector immunity for adenoviral isolate Y25 (van Doremalen et al., 2020, Nature). It has also been demonstrated that immunogenicity is a product of infectivity of the Y25 adenoviral vector preparation (Dicks et al., 2012, PLoS One). ChAdOx1 is an adenoviral vector derived from Y25 (van Doremalen et al., 2020, Nature), currently in trial use for the SARS-CoV-2 vaccine AZD1222 by AstraZeneca. The aforementioned study in Nature demonstrated 9% pre-existing anti-vector immunity among the Gambian population (ibid.). Consequently, any SARS-CoV-2 vaccine based on Y25 adenoviral isolates, specifically, the vaccine described as AZD1222, may not be ideally suited to elicit optimum immunogenic responses to SARS-CoV-2 in Gambians, and potentially other persons of African ancestry. We recommend that further studies be conducted to assess the ethical implications of any Y25-derived SARS-CoV-2 vaccine designed for distribution among global populations to mitigate further disparities in outcomes among ethnic minorities due to SARS-CoV-2 2019 infection, causing COVID-19."
A Renewed Call for Vaccine Equity by NCHEALTHEQ
North Carolina Health Equity Project, Inc. is particularly encouraged by the work of scientists and researchers including Madhi et al. for continued research and investigation into Y25-derived vectors including ChAdOx1.
We advocate for COVID-19 vaccines that are equitable in efficacy, access, and distribution.
We explicitly endorse the current vaccines distributed under Emergency Use Authorization in the United States.
We encourage further investigation into ChAdOx1 derivative vaccines and appropriateness for global distribution, to ensure health equity for all people.
Read more about variant classification from CDC at SARS-CoV-2 Variant Classifications and Definitions (cdc.gov).
Read the full article from Madhi et al. at Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B.1.351 Variant | NEJM.
Read more about ChAdOx1 at Nature, ChAdOx1 nCoV-19 vaccine prevents SARS-CoV-2 pneumonia in rhesus macaques | Nature.
Read North Carolina Health Equity Project, Inc.'s full statement on ChAdOx1-derived vaccines for global distribution, please see the Federal Register or visit Regulations.gov (https://www.regulations.gov/comment/FDA-2020-D-1137-0076).
 ChAdOx1 nCoV-19 vaccine prevents SARS-CoV-2 pneumonia in rhesus macaques | Nature Nature 2020; 586:578–582
 Thrombotic Thrombocytopenia after ChAdOx1 nCov-19 Vaccination | NEJM N Engl J Med 2021; 384:2092-2101
 Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B.1.351 Variant | NEJM N Engl J Med 2021; 384:1885-1898
This article has been independently reviewed for accuracy by our Scientific Advisory Board and is intended for academic or research audiences.
Part of health disparities news and research reporting by North Carolina Health Equity Project, Inc. The views expressed by the authors of any cited publication(s) or external link(s) do not necessarily reflect the views of North Carolina Health Equity Project, Inc., nor are any affiliations or endorsements implied.
The Mission and Vision of North Carolina Health Equity Project, Inc.
North Carolina Health Equity Project, Inc., NCHEALTHEQ™, develops adaptive, intelligent, next-generation technologies to improve health outcomes for all people, especially those in marginalized communities. We leverage the power of cross-disciplinary innovation and disruptive technologies including AI/ML, “accelerating research and saving lives.” Learn more at https://www.nchealtheq.org/.
Corporate and Governmental Affairs
North Carolina Health Equity Project, Inc.