Seven-month kinetics of SARS-CoV-2 antibodies and protective role of pre-existing antibodies to seasonal human coronaviruses on COVID-19

Abstract

Unraveling long-term kinetics of antibodies to SARS-CoV-2 and the factors influencing its course, like prior antibody levels to human coronaviruses causing common cold (HCoVs), is essential to understand protective immunity and effective surveillance strategies. Antibody levels against six SARS-CoV-2 and four HCoV antigens were quantified by Luminex, and antibody neutralization capacity was assessed by flow cytometry in a cohort of health care workers followed-up for 6 months. Seroprevalence increased over time from 13.5% (month 0) and 15.6% (month 1), to 16.4% (month 6). Levels of antibodies were stable over time, except IgG against nucleocapsid antigen and IgM levels that waned. After the peak response, anti-spike antibody levels increased from ~150 days post-symptom onset in all individuals (73% for IgG), in the absence of any evidence of re-exposure. The neutralizing capacity of antibodies was maintained. Pre-existing antibodies to alpha-HCoV were lower in individuals who subsequently seroconverted for SARS-CoV-2. IgG and IgA to HCoV were significantly higher in asymptomatic than symptomatic seropositive individuals. Thus, pre-existing cross-reactive HCoVs antibodies could have a protective effect against SARS-CoV-2 infection and COVID-19 disease.

Persistence and baseline determinants of seropositivity and reinfection rates in health care workers up to 12.5 months after COVID-19

“…Therefore, there was a minimal overall rate of symptomatic reinfection of 2/173 (1.16%). This rate contrasts with what we found in another HCW cohort that we followed up for 7-month seroprevalence in which no reinfections were detected [19,5]. It could be that primary HCW are more at risk of reinfection than hospital-based HCW, although it should be pointed out that is based on limited sample size.…”

“…The study also provides some evidence that a lack of S antibody response is a risk factor for symptomatic reinfection while positive serology leads to asymptomatic reinfection (Table 1). This is relevant due to the strong correlation (rho=0.9) between antibody levels to S and RBD with neutralizing function that are thought to confer protection [5].…”

“…Diversity in epitope speci city, quality and functional capacity of antibodies will likely affect the e cacy of the immunity mediated. Antibodies elicited after exposure to SARS-CoV-2 have been associated with protective immunity up to 6 months [2][3][4][5], although we do not yet have a correlate of protection, and reinfections occur seemingly at a low frequency. The spike (S) protein on the virus surface is considered the main target of protective antibodies, and the component of the leading vaccines [6] already under implementation.…”

“…The duration of protective antibodies is a critical question as reinfection rates may increase if immunity wanes. Although initial reports indicated a decline in antibodies after 3 months [8], subsequent studies have shown relatively stable antibody levels, mostly IgG, over a period of up to 6 months and beyond [1][2][3][4][5][9][10][11][12][13][14][15][16][17]. As massive global immunization campaigns advance, this knowledge will give clues as to how long COVID-19 vaccine immunity might last and how preexisting SARS-CoV-2 antibodies and other baseline variables could affect vaccine effectiveness.…”

Pre-existing antibodies targeting a linear epitope on SARS-CoV-2 S2 cross-reacted with commensal gut bacteria and shaped vaccine induced immunity

“…Next, Vero cells were added into each well (2×10 4 cells/well) and the plates were incubated at 37°C in a humidified incubator with 5% CO2. 24 (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.…”