Persistence of SARS-CoV-2 specific B- and T-cell responses in convalescent COVID-19 patients 6-8 months after the infection

Abstract

Background: The longevity of the immune response against SARS-CoV-2 is currently debated. We thus profiled the serum anti-SARS-CoV-2 antibody levels and virus specific memory B- and T-cell responses over time in convalescent COVID-19 patients. Methods: A cohort of COVID-19 patients from the Lombardy region in Italy who experienced mild to critical disease and Swedish volunteers with mild symptoms, were tested for the presence of elevated anti-spike and anti-receptor binding domain antibody levels over a period of eight months. In addition, specific memory B- and T-cell responses were tested in selected patient samples. Results: Anti-SARS-CoV-2 antibodies were present in 85% samples collected within 4 weeks after onset of symptoms in COVID-19 patients. Levels of specific IgM or IgA antibodies declined after 1 month while levels of specific IgG antibodies remained stable up to 6 months after diagnosis. Anti-SARS-CoV-2 IgG antibodies were still present, though at a significantly lower level, in 80% samples collected at 6-8 months after symptom onset. SARS-CoV-2-specific memory B- and T-cell responses were developed in vast majority of the patients tested, regardless of disease severity, and remained detectable up to 6-8 months after infection. Conclusions: Although the serum levels of anti-SARS-CoV-2 IgG antibodies started to decline, virus-specific T and/or memory B cell responses increased with time and maintained during the study period (6-8 months after infection).

T cell response to SARS-CoV-2 infection in humans: A systematic review

“…However, this evidence derives from small, observational studies conducted on samples taken from participants at varying time points, and with selection criteria rarely described. The longevity of this T cell immunity and the degree of protection it provides remains unclear, though recent pre-print papers from studies with longer follow-up report durability of virus-specific T cells for as long as 6–8 months following infection [ 83 , 84 ]. Recent epidemiological and animal model evidence hints at the protective function of T cells [ 85 , 86 ], and is supported by identification of detectable virus-specific T cell responses in seronegative COVID-19 convalescents [ 87 – 89 ], and in uninfected individuals with known exposure [ 90 ].…”

Reduced binding and neutralization of infection- and vaccine-induced antibodies to the B.1.351 (South African) SARS-CoV-2 variant

“…The receptor binding motif within the spike protein interacts with the ACE2 receptor and is a major target of antibody-mediated neutralization. Longitudinal and cross-sectional studies have estimated that antibodies to the spike protein can last for at least a year following infection (Anand et al, 2021; Dan et al, 2021; Pradenas et al, 2021; Sherina et al, 2021). The mRNA-1273 vaccine encodes the viral spike protein and elicits a potent neutralizing antibody response to SARS-CoV-2 that is durable for several months (Anderson et al, 2020; Jackson et al, 2020; Widge et al, 2021).…”

“…Recent studies have found that binding and neutralizing antibodies are maintained for at least eight months following SARS-CoV-2 infection (Dan et al, 2021; Pradenas et al, 2021; Sherina et al, 2021). To understand how antibody breadth is impacted during convalescence, we performed a longitudinal analysis of RBD binding and viral neutralization in 30 convalescent COVID-19 individuals across two longitudinally sampled timepoints through 8 months ( Supplementary Table 2 ).…”

SARS-CoV-2 infection: molecular mechanisms of severe outcomes to suggest therapeutics

“…Immune repertoire sequencing suggests the T-cell repertoire to decrease in early infection followed by an expansion in convalescent production phase, while the B-cell repertoire has isotype switching and clonal expansion [ 168 ]. These responses have been shown to last for 6–8 months [ 169 ], with further need for longitudinal follow up to determine the length of adaptive resistance to the virus. This immune repertoire sequencing combined with single-cell RNAseq has been pivotal in the rapid determination of neutralizing antibodies to the SARS-CoV-2 virus [ 170 ], opening the door for the rapid generation of viral neutralizing drugs.…”