T-Cells May Be Sufficient to Provide Protection from COVID-19, Finds New Study

Data released from a prospective cohort study in key workers in the UK demonstrates that SARS-CoV-2 reactive T cells may be sufficient to give protection from COVID-19 and that serology alone may underestimate those at lower risk of clinical SARS-CoV-2 infection.

The data showing SARS-CoV-2 reactive T cells are associated with protection from COVID-19 and can be both detected and measured came from a study which investigated both antibody (serology) and T cell responses in a cohort of police, fire and healthcare workers using Oxford Immunotec’s (Oxford, UK) T-SPOT technology. In the study, T cell tests were conducted at enrolment in almost 3,000 participants using the company’s standardized research use only T-SPOT Discovery SARS-CoV-2 assay. These individuals were then followed up for subsequent development of symptomatic, PCR confirmed SARS-CoV-2 infection. None of the participants with a high T cell response developed symptomatic SARS-CoV-2 infection in the follow-up period, whereas amongst those with low T cell responses there were 20 confirmed infections. Further follow-up is planned allowing for updated analyses as case numbers rise which may help yield additional insights into disease risk.

These, and additional results from the data, suggest that serology alone may underestimate the working age population at lower risk of clinical SARS-CoV-2 infection. Moreover, individual level risk stratification may be possible using T cell assays. Additionally, the numbers of individuals with high levels of SARS-CoV-2 responsive T cells declines with increasing age, specifically in the absence of antibodies (serology), and this may explain higher illness incidence and severity in this group. The T-SPOT Discovery SARS-CoV-2 test detected PCR confirmed SARS-CoV-2 infections that were not positive in antibody (serology) testing.

“We conducted a prospective cohort study in almost three thousand volunteers working in hospitals, and in the fire and police services in England,” said Dr. David Wyllie, Consultant Microbiologist at Public Health England and the lead author of the study. “Four months into the study, 20 participants with lower T cell responses had developed COVID-19, compared with none among individuals with higher T cell responses. This suggests individuals with higher numbers of T-cells recognizing SARS-CoV-2 may have some level of protection from COVID-19, although more research is required to confirm this.”

“Our T-SPOT technology platform is the only globally regulated ELISPOT platform currently available and we are pleased that we may be able to use it to support efforts to combat COVID-19,” said Oxford Immunotec CEO, Dr Peter Wrighton-Smith.

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