Heterologous immunization with Covishield and Pfizer vaccines against SARS-CoV-2 elicits a robust humoral immune response

Ali Toloue Ostadgavahi, Ryan Booth, Gary Sisson, Nichole McMullen, Michelle Warhuus, Peter Robertson, Matthew Miller, Wanda C. Allen, May El Sherif, Robert Brownlie, Darryl Falzarano, Christopher D. Richardson

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Understanding the efficacy and durability of heterologous immunization schedules against SARS-CoV-2 is critical, as supply demands and vaccine choices become significant issues in the global vaccination strategy. Here we characterize the neutralizing antibodies produced in two subjects who received combination immunizations against SARS-CoV-2, first with Covishield (Oxford–AstraZeneca) vaccine, followed 33 days later with a second dose (booster) shot of the Pfizer-BioNTech vaccine. Serum samples were collected 25 days following the primary vaccination and 13 days after the secondary Pfizer vaccination. Both subjects exhibited increased levels of isotype IgG and IgM antibodies directed against the entire spike protein following immunizations. These antibodies also exhibited increased reactivity with the receptor binding domain (RBD) in the spike protein and neutralized the infectivity of replicating vesicular stomatitis virus (VSV) that contains the COVID-19 coronavirus S protein gene in place of its normal G glycoprotein. This VSV pseudovirus also contains the reporter gene for enhanced green fluorescent protein (eGFP). Antibody titers against the spike protein and serum neutralization titers against the reporter virus are reported for the 2 heterologous vaccinated individuals and compared to a positive control derived from a convalescent patient and a negative control from an unexposed individual. The Pfizer-BioNTech vaccine increased antibody binding to the spike protein and RBD, and approached levels found in the convalescent positive control. Neutralizing antibodies against the VSV-S pseudovirus in the 2 subjects also approached levels in the convalescent sera. These results firmly validate the value of the Pfizer-BioNTech vaccine in boosting immunity following initial Covishield inoculation.

Original languageEnglish
Pages (from-to)653-656
Number of pages4
JournalJournal of Infection in Developing Countries
Volume15
Issue number5
DOIs
Publication statusPublished - May 2021

Bibliographical note

Funding Information:
We acknowledge research support from Canadian Institutes of Health Research Operating Grants (CIHR OV5-170349 and CIHR-MOP-117575), a Canadian Institutes of Health Research COVID-19 Rapid Research Funding Opportunity - Vaccines - 2020-05-11 (CIHR-FRN-172770), and Dalhousie Medical Research Fund/Research Nova Scotia Rapid Response and Coalition for COVID-19 Research Awards. Blood collection was performed with patient consent and procedures were performed by the Canadian Center of Vaccinology following review and approval by the Dalhousie University/IWK Health Sciences Centre Human Ethics Approval Committee.

Publisher Copyright:
© 2021 Journal of Infection in Developing Countries. All rights reserved.

ASJC Scopus Subject Areas

  • Parasitology
  • Microbiology
  • Infectious Diseases
  • Virology

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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