SARS CoV-2 infections in healthcare workers with a pre-existing T-cell response: a prospective cohort study

Abstract

Objective T-cell responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are observed in unexposed individuals. We evaluated the impact of this pre-existing cellular response on incident SARS CoV-2 infections. Methods Follow up study of 38 seronegative health care workers (HCWs) with previous evaluation of CD8+ and CD4+ T-cell response after stimulation with SARS-CoV-2 structural proteins. Infection was considered in presence of a positive reverse transcription (RT)-PCR test and/or confirmed seroconversion. Results Twenty of the 38 HCWs included (53%) had a previous specific CD8+ T cell response to peptides encompassing the spike (S) protein in 13 (34%), the membrane (M, 17, 45%), or/and the nucleocapsid (N, 3, 8%). During a follow up of 189 days (interquartile range, IQR, 172 to 195), 11 (29%) HCWs had a RT-PCR positive test (n=9) or seroconverted (n=2). Median duration of symptoms was 2 days (IQR, 0-7), and time to negative RT-PCR was 9 days (IQR, 4-10). Notably, six incident infections (55%) occurred in HCWs with pre-existing T-cell response (30% of those with cellular response), who showed a significant lower duration of symptoms (three were asymptomatic). Three of the six HCWs having previous T-cell response continued testing seronegative. All the infected patient developed a robust T-cell response to different structural SARS-CoV-2 proteins, especially to protein S (91%). Conclusion Pre-existing T-cell response does not seems to reduce incident SARS-CoV-2 infections, but it may contribute to asymptomatic or mild disease, rapid viral clearance and differences in seroconversion.

T‐cell response after first dose of BNT162b2 SARS‐CoV‐2 vaccine among healthcare workers with previous infection or cross‐reactive immunity

“…Fifty HCWs evaluated 3 months before vaccination (median, 103 days; IQR, 90–112) in a cross‐sectional study about humoral and T‐cell response to SARS‐CoV‐2 10 underwent blood analysis at least 17 days after the first dose of BNT162b2 vaccine. Characteristics of enrolled individuals are shown in Table 1 .…”

SARS-CoV-2 Omicron: Light at the End of the Long Pandemic Tunnel or Another False Dawn for Immunodeficient Patients?

“…19 In contrast, there is increasing evidence that cellular immune responses play a crucial role in both the outcome of COVID-19 and long-term protection after infection or vaccination. [20][21][22] A low avidity or delayed T-cell response is associated with severe outcomes in COVID-19. 20 An efficient early T-cell response can protect against SARS-CoV-2 and even abort the infection before quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) tests become positive.…”

Common Variable Immunodeficiency Disorders, T-Cell Responses to SARS-CoV-2 Vaccines, and the Risk of Chronic COVID-19

“…28 Recent studies suggest that an effective early T-cell response is correlated with milder disease. [31][32][33] In contrast, long-term protection is linked to the generation of a robust memory T-cell response. 34,35 In many patients with mild COVID-19, antibody responses were muted, but these individuals generated an effective cellular response.…”