"It is too early to say that this study means people are protected long term after infection as we don’t yet know, but this kind of study is important and further longitudinal studies will be equally important. These studies are also important as they demonstate antibody assays alone may not be sufficient to measure an individal’s immunity to SARSCovid 19."
“This study is promising for vaccine development and gives a feasible justification for optimism about re-infection being rare.”
Dr Alison Whitelegg on behalf of the Association for Clinical Biochemistry’s Immunology Professional Committee.
"It is, therefore, not necessarily correct to say that this is evidence of T cell “immunity”. Immunity is a functional term that implies resistance to infection, and this has not been directly shown in this study. Determining whether these T cell responses are protective against reinfection would require either an experimental infection study (such studies are under active discussion) or a very large, long term study to assess the frequency of reinfection in people whose T cell responses have been measured. "
Prof Eleanor Riley, Professor of Immunology and Infectious Disease, University of Edinburgh
" If cellular immunity is a good correlate of protection to re-infection, this provides encouraging data for long-term immunity to SARS-Cov-2 and the development of effective vaccines – however this study cannot tell us whether people are protected from re-infection, so we still need more data first. "
Prof Brendan Wren, Professor of Microbial Pathogenesis, London School of Hygiene & Tropical Medicine
"Overall, the work provides a welcome dose of optimism that SARS-CoV2 infection (and immunisation?) can induce a robust and sustained protective immune response, although this does not yet prove immunity to further infections which will require longer term surveillance and larger cohorts.”
Prof Paul Morgan, Director of the Systems Immunity Research Institute, Cardiff University.
"These results provide reassurance that, although the titre of antibody to SARS-CoV-2 can fall below detectable levels within a few months of infection, a degree of immunity to the virus may be maintained. However, the critical question remains: do these persistent T cells provide efficient protection against re-infection? It will also be important to follow the antibody and T cell immunity in people who develop the syndrome of Long Covid – the persistent and sometimes debilitating condition that follows acute SARS-CoV-2 infection in a still uncertain proportion of people. Finally, the data in this paper reinforce the need for care in interpreting the results of serological (antibody) tests: it is still unclear how well either the antibody titre or the T cell frequency correlate with actual protection against reinfection.”
Prof Charles Bangham FRS FMedSci, Chair of Immunology, Imperial College London.
www.sciencemediacentre.org/expert-reaction-to-preprint-looking-at-cellular-responses-six-months-after-sars-cov-2-infection-in-a-group-of-non-hospitalised-individuals/