The antibody response in patients who have recovered from coronavirus is not typically strong, and declines sharply one month after hospital discharge, a study suggests. A better understanding of antibody responses against SARS-CoV-2, the virus that causes COVID-19, will provide fundamental information for developing effective treatments and a preventive coronavirus vaccine, experts say.
In the study, researchers monitored SARS-CoV-2-specific antibody responses in 19 non-severe and 7 severe COVID-19 patients for seven weeks from disease onset. They found that most patients generated antibody responses against SARS-CoV-2.
According to the study, although 80.7% of recovered COVID-19 patients had varying levels of antibody neutralisation activity against SARS-CoV-2, only a small portion elicited a potent level of neutralisation activity.
Researchers say this highlights the importance of carefully selecting blood samples from recovered patients using antibody neutralisation assays prior to transfusion into other COVID-19 patients.
The study indicates that three to four weeks after hospital discharge, the neutralising activity of antibodies from recovered patients declined significantly.
The authors from Nanjing University Medical School in China say: “The world is facing an unprecedented challenge with communities and economies affected by the growing pandemic of (COVID-19).”
The authors add: “The development of antibody response to SARS-CoV-2, the virus that causes COVID-19, started to be reported but remained largely elusive.
“Understanding the adaptive responses where the body makes antibodies that specifically bind to the SARS-CoV-2 among COVID-19 patients provides fundamental information for developing [an] effective treatment and preventive vaccine.”
Danny Altmann, professor of immunology at Imperial College London, and British Society for Immunology spokesperson, said: “After the initial publications about SARS-CoV-2 antibody assays and levels, important papers are starting to emerge which look at specificity and durability of the response in more detail.
“Studies like this are a vital part of the ‘work-in-progress’ to make sense of who has immunity and how long for.
“This paper makes a number of points: the gold-standard in assessing the antibody response to a virus is measuring ability to neutralise the entry of virus into cells, although this is not one of the routinely available tests.
He added: “Most convalescent patients show this response, though, importantly, 20 per cent do not. Also, this antibody level declines in most people by the time of their follow-up appointment a month later.
“Once again, evidence shows that the half-life of these antibodies in the blood is not particularly sustained.
“We don’t know to what extent this is bad news unless we know the extent to which the white blood cells that make the antibody (B cells) are up and ready to defend against any repeat attack.”
Abstract
There is an urgent need for effective treatment and preventive vaccine to contain this devastating global pandemic, which requires a comprehensive understanding of humoral responses specific to SARS-CoV-2 during the disease progression and convalescent phase of COVID-19 patients. We continuously monitored the serum IgM and IgG responses specific to four SARS-CoV-2 related antigens, including the nucleoprotein (NP), receptor binding domain (RBD), S1 protein, and ectodomain (ECD) of the spike protein among non-severe and severe COVID-19 patients for seven weeks since disease onset. Most patients generated humoral responses against NP and spike protein-related antigens but with their distinct kinetics profiles. Combined detection of NP and ECD antigens as detecting antigen synergistically improved the sensitivity of the serological assay, compared to that of using NP or RBD as detection antigen. 80.7% of convalescent sera from COVID-19 patients revealed that the varying extents of neutralization activities against SARS-CoV-2. S1-specific and ECD-specific IgA responses were strongly correlated with the neutralization activities in non-severe patients, but not in severe patients. Moreover, the neutralizing activities of the convalescent sera were shown to significantly decline during the period between 21 days to 28 days after hospital discharge, accompanied by a substantial drop in RBD-specific IgA response. Our data provide evidence that are crucial for serological testing, antibody-based intervention, and vaccine design of COVID-19.
Authors
Yuxin Chen, Xin Tong, Yang Li, Bin Gu, Jiawei Yan, Yong Liu, Han Shen, Rui Huang, Chao Wu
[link url="https://www.sciencefocus.com/news/covid-19-immunity-declines-sharply-a-month-after-hospital-discharge/"]Science Focus Magazine material[/link]
[link url="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008796"]PLOS Pathogens abstract[/link]
See also
[link url="https://www.medicalbrief.co.za/wp-admin/post.php?post=113491&action=edit"]Protective immunity to seasonal coronaviruses may be short-lasting[/link]