This is a summary, written by members of the CITF Secretariat, of:

Tania Watts, Lessons learned from monitoring T cell responses to SARS-CoV-2 infection and vaccination, presented at the CITF Scientific Meeting, Vancouver, Canada. March 8-10, 2023.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study that presented results at the CITF Scientific Meeting in Vancouver found that T cells are an important part of the immune response, working along with antibodies to respond effectively to SARS-CoV-2 infection. Immune responses after COVID-19 vaccination were also assessed in individuals with immune-mediated inflammatory diseases (IMID), revealing that the third vaccine dose reduced waning of immunity. The study was led by Dr. Tania Watts (University of Toronto).

Key findings:

  • The most predominant cytokineSmall proteins important in cell signaling and affect the immune systemSmall proteins important in cell signaling and affect the immune system in the SARS-CoV-2 response in patients with mild disease was IL-2, produced by T cells. This persisted for up to nine months after symptoms began. In hospitalized patients, the predominant cytokine was TNF (tumor necrosis factor) produced by T cells.
  • The SARS-CoV-2 spike-specific response was dominated by a strong CD4 and a weak CD8 response.
  • The third vaccine dose reduced waning immunity and was critical for neutralizing variants of concern in IMID patients being treated with anti-TNF.
  • The fourth vaccine dose maintained antibody and neutralization responses up to three months after vaccination and increased T cell IL-4 production in the anti-TNF/combination treatment group.

Altogether, researchers showed that T cells play a critical role in the immune response against SARS-CoV-2. Results also support additional vaccine boosting in IMID patients due to rapid waning of immunity.