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

Abstract

Background Monitoring the adaptive immune responses during the natural course of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection provides useful information for the development of vaccination strategies against this virus and its emerging variants. We thus profiled the serum anti-SARS-CoV-2 antibody levels and specific memory B- and T-cell responses in convalescent coronavirus disease-2019 (COVID-19) patients. Methods Altogether 119 samples from 88 convalescent donors who experienced mild to critical disease were tested for the presence of elevated anti-spike and anti-receptor binding domain antibody levels over a period of eight months. In addition, level of SARS-CoV-2 neutralizing antibodies, specific memory B- and T-cell responses were tested in a subset of samples. Findings Anti-SARS-CoV-2 antibodies were present in 85% of the samples collected within 4 weeks after onset of symptoms in COVID-19 patients. Levels of specific IgM/IgA antibodies declined after 1 month while levels of specific IgG antibodies and plasma neutralizing activities remained relatively stable up to 6 months after diagnosis. Anti-SARS-CoV-2 IgG antibodies were still present, though at a significantly lower level, in 80% of the samples collected at 6-8 months after symptom onset. SARS-CoV-2-specific memory B- and T-cell responses developed with time and were persistent in all patients followed up till 6-8 months. Conclusions Our data suggest that protective adaptive immunity following natural infection of SARS-CoV-2 might persist for at least 6-8 months, regardless of disease severity. Development of medium or long-term protective immunity through vaccination might thus be possible. Funding EU-ATAC consortium, the Italian Ministry of Health and SciLife/KAW.

kinetics of anti-SARS-CoV-2 antibodies over time. Results of 10 month follow up in over 300 seropositive Health Care Workers

“…Most of the cohorts with up to 5-6 months follow-up have showed high percentages in persistence of seropositivity (80% or higher). 11) , 12) , 13) , 14) , 15) , 16) However, the majority of them have also reported a relevant decrease in antibody titers over time, with one of them estimating a 2-fold decrease of IgG antibodies time of 158 days. 15 In our cohort, the model estimated a mean time to loss antibodies of 375 days from baseline.…”

Disparities in the Evolution of the COVID-19 Pandemic between Spanish Provinces

“…These provinces do not correspond to any CI 14 cluster, but there are differences in the seroprevalence values in November for each CI 14 club: clubs 1 and 2 had on average seroprevalences lower than 6.2%, and clubs 3 and 4 greater than 7.4%; in Madrid figure was 12.5%. IgG antibodies are only part of the anamnestic immune response, and memory cells play a fundamental role in adaptive cellular immunity; development of memory B and T cells is critical for long-term protection [ 75 , 76 ]. Although the serum levels of anti-SARS-CoV-2 IgG antibodies show a decline at months 6–8, virus-specific T and/or memory B cell responses increase with time and are maintained during at least 6–8 months after infection [ 76 , 77 , 78 , 79 ].…”

“…IgG antibodies are only part of the anamnestic immune response, and memory cells play a fundamental role in adaptive cellular immunity; development of memory B and T cells is critical for long-term protection [ 75 , 76 ]. Although the serum levels of anti-SARS-CoV-2 IgG antibodies show a decline at months 6–8, virus-specific T and/or memory B cell responses increase with time and are maintained during at least 6–8 months after infection [ 76 , 77 , 78 , 79 ]. Asymptomatic infected patients generate a weaker immune response [ 80 ], and some COVID-19 patients experience a decline in B cell responses over a timescale of 3 months [ 81 , 82 , 83 ], so T cell responses may be more sensitive indicators for SARS-CoV-2 infection prevalence than seropositivity [ 84 ].…”

Passive Immunity Should and Will Work for COVID-19 for Some Patients

“…Whether for enzyme immunoassay-detected antibody (or similar) or neutralizing antibody, the total specific antibody level peaks after 3-10 weeks [30,[51][52][53][54][55][56][57][58][59][60]. As anticipated, IgM reactivity diminishes over the first few months while IgG reactivity continues to be detected for a much longer interval [54,56,57,59,[61][62][63][64][65][66][67].…”