COVID-19 vaccines protect against variants, study suggests

A research group from the Johns Hopkins University Medical School has published a new study suggesting that certain COVID-19 vaccines may protect against variant coronavirus strains.1 These include the variants first identified in the UK and South Africa.

The study analyzed the response of the SARS-CoV-2 virus and three other cold coronaviruses after administration of an mRNA-based COVID-19 vaccine. Blood samples from 30 healthcare workers who had not tested positive for COVID-19 were analyzed before and after receiving the COVID-19 vaccine from Pfizer-BioNTech or Moderna.

The study model focused on the coronavirus surface proteins – spike proteins – that help viruses gain access to and infect host cells. A type of immune cell called helper T cells or CD4 + T cells recognizes these viral proteins on cells infected with coronavirus and promotes cell destruction. The mRNA-based COVID-19 vaccines contain a code that enables healthy cells to produce these spike proteins. This promotes the development of a CD4 + T cell response that is specific for coronavirus spike proteins. The CD4 + T cell response was analyzed using pre- and post-vaccination blood samples to indicate vaccine effectiveness.

As expected by the research group, the vaccinated participants showed a stronger CD4 + T cell response to SARS-CoV-2 after vaccination. But other coronavirus variants were also tested to understand the effectiveness of the COVID-19 vaccine against variants.

Variants of SARS-CoV-2 differ in some components of their spike proteins. When testing the common cold coronaviruses HCoV-NL63, HCoV-229E, and HCoV-OC43, researchers measured the level of immunity provided upon exposure to the variants.

The research group observed a broad T cell response to the SARS-CoV-2 virus and was able to identify 23 different viral proteins that coronavirus-specific T cells target.

Four of these 23 peptides can be modified in variants B.1.1.7 in Great Britain and B.1.351 in South Africa. This suggests that the 19 other peptides (building blocks) among the coronaviruses are constant and attacked by vaccine-induced CD4 + T cells when exposed to the SARS-CoV-2 virus and other emerging variants.

Findings from another study from the Johns Hopkins School of Medicine confirmed the importance of the CD4 + T cell response to SARS-Cov-2 and cold coronaviruses. They tested the T cell response to spike proteins in patients who had recovered from COVID-19 as well as those who were not exposed. In 65% of the participants, memory CD4 + T cells recognized spike proteins from SARS-CoV-2 and at least one other cold coronavirus

The cross-detection observed by CD4 + T cells led the researchers to conclude that mRNA-based COVID-19 vaccines can protect against SARS-CoV-2 variants. The effectiveness of the COVID-19 vaccine against variants needs further research to fully understand the level of protection.

References

B.A. Woldemeskel et al. (2021). SARS-CoV-2 mRNA vaccines induce broad CD4 + T cell responses that recognize SARS-CoV-2 variants and HCoV-NL63. The Journal of Clinical Investigation, Preview in the Press. Doi: 10.1172 / JCI149335.
Dykema, A.G. et al. (2021). Functional characterization of CD4 + T cell receptors that are cross-reactive for SARS-CoV-2 and endemic coronaviruses. The Journal of Clinical Investigation, Preview in the Press. Doi: 10.1172 / JCI146922.
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