COVID-19 Alpha Variant (B.1.1.7): Humoral, memory B and T cells in COVID-19 pediatric convalescents.

BACKGROUND: Studies of anti-SARS-CoV-2 humoral and adaptive response in COVID-19 non-vaccinated pediatric convalescents are controversial and further evidence from the pediatric population are needed. OBJECTIVES: To elucidate SARS-CoV-2 humoral and memory B- and T-cells responses in pediatric convalescents as compared with the adult. METHODS: Blood samples were obtained from 80 non-vaccinated, IgG-positive, COVID-19 convalescents (age 8.0-61.0 years), 4.0 months from onset. Frequency of responders and magnitudes of SARS-COV-2 IgG, memory B-cells (MBC) and IFNg- and IL2-secreting memory T-cells (MTC) in response to immuno-dominant peptide pools in pediatric, young adults and middle-aged adults with onset age 8-18 years (N = 20), 19-39 years (N = 30) and 40-61 years (N = 30), respectively, were analyzed. SARS-CoV-2 IgG were detected by ELISA (Euroimmun, Germany). MBC, IFNg-, IL2- and IFNg+IL2-secreting MTC (IFNg-MTC, IL2-MTC and IFNg+IL2-MTC) were detected using FluoroSpot (Mabtech, Sweden). RESULTS: MBC level was lower in pediatric as compared with the middle-aged adults (median 12.75 interquartile range [IQR] 4.27-33.7 and 32.0 IQR 6.0-124.2, respectively, p = .003). MBC level in young adults was lower than in middle-aged adults (median 18.5 IQR 1.7-43.8 and 32.0 IQR 6.0-124.2, respectively, p = .006). The level of IL2-MTC was lower in the pediatric group as compared with middle aged-adults (median 2.1 IQR 0-16.9 and 28.6 IQR 11-49.6, respectively, p < .03) and in young adults lower than in middle-aged adults (median 1.45 IQR 0-18.6 and 28.6 IQR 11-49.6, respectively, p = .02). In addition, the level of IFNg-MTC was lower in pediatric as compared with young adults (median 4.25 IQR 0.0-15.0 and 20.9 IQR 0-75.2, respectively, p = .05). The level of IgG was comparable between pediatric and both young and middle-aged adult groups (4.82 ± 2.95, 3.70 ± 2.65 and 4.9 ± 2.94, respectively, p > .34). CONCLUSION: Non-vaccinated COVID-19 pediatric convalescents have lower adaptive immune responses than adults sustaining the recommendation for vaccination of the pediatric population.

SARS-CoV-2 memory B and T cell profiles in mild COVID-19 convalescent patients.

OBJECTIVES: Antiviral adaptive immunity involves memory B cells (MBC) and memory T cells (MTC). The dynamics of MBC and MTC in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) convalescents warrant further investigation. METHODS: In this cross-sectional and longitudinal study, blood-derived MBC and MTC responses were evaluated in 68 anti-spike IgG-positive mild coronavirus disease 2019 (COVID-19) convalescents at visit 1, between 1 and 7 months (median 4.1 months) after disease onset. SARS-CoV-2 anti-spike IgG was determined by ELISA, MBC by SARS-CoV-2-specific receptor binding domain (RBD) ELISpot, and interferon gamma (IFN-γ)-, interleukin 2 (IL2)-, and IFN-γ+IL2-secreting MTC by IFN-γ and IL2 SARS-CoV-2 FluoroSpot. For 24 patients sampled at the first visit, the IgG, MBC, and MTC analyses were also performed 3 months later at the second visit. RESULTS: Seventy-two percent of convalescents were both MBC- and MTC-positive, 18% were MBC-positive and MTC-negative, and 10% were MTC-positive and MBC-negative. The peak MBC response level was detected at 3 months after COVID-19 onset and persisted up to 7 months post infection. Significant MTC levels were detected 1 month after onset in response to S1, S2_N, and SNMO peptide pools. The frequency and magnitude of the MTC response to SNMO was higher than those to S1 and S2_N. Longitudinal analysis demonstrated that even when specific humoral immunity declined, the cellular immunity persisted. CONCLUSIONS: The study findings demonstrate the durability of adaptive cellular immunity at least for 7 months after SARS-CoV-2 infection, suggesting long-lasting protection.

Humoral immune response in multiple sclerosis patients following PfizerBNT162b2 COVID19 vaccination: Up to 6 months cross-sectional study.

Appropriate immune response following COVID-19 vaccination is important in the context of disease-modifying treatments (DMTs). In a prospective cross-sectional study, we determined SARS-COV-2 IgG response up to 6 months following PfizerBNT162b2 vaccination in 414 multiple sclerosis (MS) patients and 89 healthy subjects. Protective response was demonstrated in untreated MS patients (N = 76, 100%), treated with Cladribine (N = 48, 100%), Dimethyl fumarate (N = 35, 100%), Natalizumab (N = 32, 100%), and Teriflunomide (N = 39, 100%), similarly to healthy subjects (N = 89, 97.8%). Response was decreased in Fingolimod (N = 42, 9.5%), Ocrelizumab (N = 114, 22.8%) and Alemtuzumab (N = 22, 86.4%) treated patients. IgG response can help tailor adequate vaccine guidelines for MS patients under various DMTs.