Cellular and humoral immune response to the fourth Pfizer-BioNTech COVID-19 vaccine dose in individuals aged 60 years and older.

With the emergence of the severe acute respiratory syndrome 2 (SARS-CoV-2) B.1.1.529/BA.1 (Omicron) variant in early 2022, Israel began vaccinating individuals 6o years of age or older with a fourth BNT162b2 vaccine. While the decision was based on little experimental data, longer follow-up showed clinical effectiveness of the fourth dose with reduction in the number of severely affected individuals. However, the immune response to fourth vaccine dose in this age group was not yet characterized, and little is known about the immunogenicity of repeated vaccine dosing in this age group. We therefore aimed to evaluate the humoral and cellular immune response pre- and 3-week post- the fourth vaccine dose in patients age 60 years or older. For this purpose, blood samples were collected from donors age 60 years or older, all received their 3rd vaccine dose 5 months prior. Serum samples were evaluated for the presence of anti-Spike protein (anti-S) antibodies (N = 133), and peripheral blood mononuclear cells (PBMCs) were evaluated by flow cytometry for their ability to respond to the SARS-CoV-2 wild type Spike-glycoprotein peptide mix, Membrane-glycoprotein (M) peptide mix and to the mutated Spike-regions of the Omicron variant (N = 34). Three weeks after the fourth vaccine dose, 24 out of 34 donors (70.5%) showed significant increase in the number of cells responding to the wild type S-peptide mix. Of note, out of 34 donors, 11 donors (32.3%) had pre-boost anti-M T-cell response, none of which had history of confirmed COVID-19, suggesting possible asymptomatic exposure. Interestingly, in M non-responding individuals, no statistically significant increase in the cellular response was observed following stimulation with omicron S-mutated regions. While there are limited data regarding the longevity of the observed response, our results are in accordance with the described clinical efficacy, provide mechanistic evidence to support it and argue against vaccine-induced or age-related immunosenescence.

Immunogenicity of Pfizer-BioNTech COVID-19 vaccine in patients with inborn errors of immunity.

BACKGROUND: In mid-December 2020, Israel started a nationwide mass vaccination campaign against coronavirus disease 2019 (COVID-19). In the first few weeks, medical personnel, elderly citizens, and patients with chronic diseases were prioritized. As such, patients with primary and secondary immunodeficiencies were encouraged to receive the vaccine. Although the efficacy of RNA-based COVID-19 vaccines has been demonstrated in the general population, little is known about their efficacy and safety in patients with inborn errors of immunity (IEI). OBJECTIVE: Our aim was to evaluate the humoral and cellular immune response to COVID-19 vaccine in a cohort of patients with IEI. METHODS: A total of 26 adult patients were enrolled, and plasma and peripheral blood mononuclear cells were collected from them 2 weeks following the second dose of Pfizer-BioNTech COVID-19 vaccine. Humoral response was evaluated by testing anti-SARS-CoV-2 spike (S) receptor-binding domain and antinucleocapsid antibody titers and evaluating neutralizing ability by inhibition of receptor-binding domain-angiotensin-converting enzyme 2 binding. Cellular immune response was evaluated by using ELISpot, estimating IL-2 and IFN-γ secretion in response to pooled SARS-CoV-2 S- or M-peptides. RESULTS: Our cohort included 18 patients with a predominantly antibody deficiency, 2 with combined immunodeficiency, 3 with immune dysregulation, and 3 with other genetically defined diagnoses. Twenty-two of them were receiving immunoglobulin replacement therapy. Of the 26 patients, 18 developed specific antibody response, and 19 showed S-peptide-specific T-cell response. None of the patients reported significant adverse events. CONCLUSION: Vaccinating patients with IEI is safe, and most patients were able to develop vaccine-specific antibody response, S-protein-specific cellular response, or both.

Prevalence of COVID-19 and seroprevalence to SARS-CoV-2 in a rheumatologic patient population from a tertiary referral clinic in Israel.

BACKGROUND: It is unclear if the prevalence of COVID-19 in rheumatologic patients is similar to that of the general population. There are no reports of seroprevalence of SARS-CoV-2 in these patients. AIMS: To investigate prevalence of COVID-19 cases and seroprevalence among rheumatologic patients and the risk factors for infection. METHODS: A cross-sectional study in a rheumatologic population. An online questionnaire was sent on 31 April 2020. Blood samples from 20% sample of patients were drawn for SARS-CoV-2 antibodies. Patients were divided based on autoimmune (AI) diagnosis. Prevalence of COVID-19 by nasopharyngeal swab and by serology (seroprevalence) was compared to national data. Risk factors for infection of SARS-CoV-2 were assessed. RESULTS: The study group included 1204 patients, 74.5% had an AI diagnosis. The prevalence of COVID-19 was 0.16% in the rheumatologic patient population and 0.22% in the AI group, which was not different from prevalence in Israel on 4 May 2020 (0.18%, P = 0.912 and P = 0.759 respectively). Serologic tests were performed in 242 patients, of which five were found positive pointing to a seroprevalence of 2.07%. Exposure to a known COVID-19 patient was the only significant risk factor for being positive by swab or by serology. AI diagnosis, immunosuppression, corticosteroid, hydroxychloroquine did not influence the risk. CONCLUSIONS: The prevalence of COVID-19 in a population of rheumatologic patients was similar to that of the general population. Mild/asymptomatic cases may be prevalent according to serologic tests. The major risk factor for infection is exposure to a known case of COVID-19, and immunosuppression did not play a role in the risk of infection.