Adaptive immune responses to SARS-CoV-2 in recovered severe COVID-19 patients

Abstract

ObjectivesThere is an imperative need to determine the durability of adaptive immunity to SARS-CoV-2. We enumerated SARS-CoV-2-reactive CD4+ and CD8+ T cells targeting S1 and M proteins and measured RBD-specific serum IgG over a period of 2-6 months after symptoms onset in a cohort of subjects who had recovered from severe clinical forms of COVID-19.MethodsWe recruited 58 patients (38 males and 20 females; median age, 62.5 years), who had been hospitalized with bilateral pneumonia, 60% with one or more comorbidities. IgG antibodies binding to SARS-CoV-2 RBD were measured by ELISA. SARS-CoV-2-reactive CD69+-expressing-IFNγ-producing-CD4+ and CD8+ T cells were enumerated in heparinized whole blood by flow cytometry for ICS.ResultsDetectable SARS-CoV-2-S1/M-reactive CD69+-IFN-γ CD4+ and CD8+ T cells were displayed in 17 (29.3%) and 6 (10.3%) subjects respectively, at a median of 84 days after onset of symptoms (range, 58-191 days). Concurrent comorbidities increased the risk (OR, 3.15; 95% CI, 1.03-9.61; P=0.04) of undetectable T-cell responses in models adjusted for age, sex and hospitalization ward. Twenty-one out of the 35 patients (60%) had detectable RBD-specific serum IgGs at a median of 118 days (range, 60 to 145 days) after symptoms onset. SARS-CoV-2 RBD-specific IgG serum levels were found to drop significantly over time.ConclusionA relatively limited number of subjects who developed severe forms of COVID-19 had detectable SARS-CoV-2-S1/M IFNγ CD4+ and CD8+ T cells at midterm after clinical diagnosis. Our data also indicated that serum levels of RBD-specific IgGs decline over time, becoming undetectable in some patients.

Association of trace element status in COVID-19 patients with disease severity

“…The different interaction between the virus and the individual’s immune system results in a much different clinical picture in patients with COVID-19. Although adaptive immune responses are essential for the neutralization of SARS-CoV-2, innate immune cells, particularly NK cells, T lymphocytes and macrophages, innate, may also play a role in disease progression [6] , [7] , [8] . Several minerals and trace elements (e.g., magnesium, iron, zinc, copper, selenium) are essential for an adequate immune response [9] and have anti-inflammatory and antioxidant properties that may be of great importance for the competent response of patients to COVID-19 [10] , [11] , [12] .…”

The prevalence of adaptive immunity to COVID-19 and reinfection after recovery – a comprehensive systematic review and meta-analysis

“…Data from 26 studies (8, 9, 11, 12, 16, 17, 29, 47, 49-53, 56, 57, 60, 63, 64, 67, 69, 71, 75, 78, 81, 82, 84), with 3092 participants were available for evaluation of the prevalence of detectable IgG after recovery. The pooled prevalence of detectable IgG after recovery was 89.0% (95%CI 72.8 – 99.0, I 2 =89.7%, p<0.01, 8 studies) within 1 month, 92.6% (95%CI 86.9 – 96.9, I 2 =57.7%, p<0.01, 4 studies) at >1 - <3 months, 91.4% (95%CI 84.5-96.3, I 2 =84.3%, p<0.01, 9 studies) at 3-<6 months and 90.4% (95%CI 72.2-99.9, I 2 =89.0%, p<0.01, 5 studies) beyond 6 months (Fig 3 and Supplementary Figs.…”