South Australian researchers have submitted for peer review one of the first publications globally to examine COVID-19 immunity one year after infection.
The research was supported by The Hospital Research Foundation Group; Women’s & Children’s Hospital Foundation; and private and public donations through THRF’s ‘Fund The Fight’ campaign last year.
The study was led by Dr Branka Grubor-Bauk (pictured) and Professor Simon Barry from the University of Adelaide, the Basil Hetzel Institute and Robinson Research Institute; in collaboration with clinicians and researchers from the Royal Adelaide Hospital, SA Pathology, The Queen Elizabeth Hospital, SAHMRI, the Kirby Institute and UNSW, as well as renowned international COVID-19 immunologists from University of California and La Jolla Institute for Immunology (USA).
A non-peer reviewed preprint of the paper has been released, stating our body’s immune system does maintain the memory to COVID-19 (also known as SARS-CoV-2 virus) 12 months later.
“Immunity to SARS-CoV-2 persists for 12 months in mild COVID-19 convalescent patients that retain high Spike-specific antibody titres, virus neutralisation capacity and circulating RBD-specific memory B cells,” the paper says.
“Significantly, T cell immunity remained stable 12 months post-infection. This study offers vital information on the duration of natural COVID-19 immunity and its potential protective effect against SARS-CoV-2 reinfection and clinical disease, with clear implications for the ongoing management of the global pandemic.”
The study analysed the data of 43 South Australian patients with mild COVID-19 12 months after their initial infection. T cells are immune cells within the body which fight off foreign substances.
Elimination of the virus in South Australia presented a globally unique opportunity because recovered patients would not have encountered the virus again. Therefore scientists were able to evaluate the strength and durability of immune memory after COVID-19 in SA patients, reflecting true natural immunity in the absence of potential virus re-exposure.
This was an important factor in the findings: “In the absence of re-exposure to SARS-CoV-2 Spike- and RBD-specific antibodies were present in 90% of COVID-19 recovered patients 12 months after infection,” the paper says.
The paper also acknowledges that many variants of COVID-19 have since emerged and are rapidly spreading across the world.
“As such, there is a growing concern that any new variants could limit the efficacy of neutralising antibodies from primary infection or the efficacy of current Spike-based vaccines.”
The team presents data that shows that although antibodies may decrease, mild COVID-19 disease still results in robust and long-lived T cell immunity that is maintained a year after infection. This finding coupled with the recent analysis which identified more than 1400 T cell targets in SARS-CoV-2, highlights the view that it is unlikely that SARS-CoV-2 variants can escape such breadth of T cell responses.
The paper concludes: “We demonstrate that immunity to SARS-CoV-2 persists for 12 months in mild COVID-19 convalescents, suggesting they retain a comprehensive arsenal of immune weapons (humoral and T cell-mediated) targeting Spike and non-Spike antigens and likely represent the majority of symptomatic patients in the world.”
“This study offers vital information on the duration of natural COVID-19 immunity and its potential protective effect against SARS-CoV-2 reinfection and clinical disease, with clear implications for the ongoing management of the global pandemic.”
Thank you to everyone who supported our Fund The Fight campaign in 2020 to support this study! A full copy of the paper’s non-peer reviewed preprint can be viewed here. We will keep you updated on when the findings are formally accepted.