Defective T-cell response to COVID-19 vaccination in acute myeloid leukaemia and myelodysplastic syndromes.

Limited data exist on COVID-19 vaccination efficacy in patients with acute myeloid leukemia and myelodysplasia with excess blasts (AML/MDS-EB2). We report results from a prospective study, PACE (Patients with AML and COVID-19 Epidemiology). 93 patients provided samples post-vaccine 2 or 3 (PV2, PV3). Antibodies against SARS-COV-2 spike antigen were detectable in all samples. Neutralization of the omicron variant was poorer than ancestral variants but improved PV3. In contrast, adequate T-cell reactivity to SARS-COV-2 spike protein was seen in only 16/47 (34%) patients PV2 and 23/52 (44%) PV3. Using regression models, disease response (not in CR/Cri), and increasing age predicted poor T cell response.

Mutations in SARS-CoV-2 spike protein impair epitope-specific CD4+ T cell recognition.

CD4+ T cells are essential for protection against viruses, including SARS-CoV-2. The sensitivity of CD4+ T cells to mutations in SARS-CoV-2 variants of concern (VOCs) is poorly understood. Here, we isolated 159 SARS-CoV-2-specific CD4+ T cell clones from healthcare workers previously infected with wild-type SARS-CoV-2 (D614G) and defined 21 epitopes in spike, membrane and nucleoprotein. Lack of CD4+ T cell cross-reactivity between SARS-CoV-2 and endemic beta-coronaviruses suggested these responses arose from naïve rather than pre-existing cross-reactive coronavirus-specific T cells. Of the 17 epitopes located in the spike protein, 10 were mutated in VOCs and CD4+ T cell clone recognition of 7 of them was impaired, including 3 of the 4 epitopes mutated in omicron. Our results indicated that broad targeting of epitopes by CD4+ T cells likely limits evasion by current VOCs. However, continued genomic surveillance is vital to identify new mutations able to evade CD4+ T cell immunity.

Vaccine subtype and dose interval determine immunogenicity of primary series COVID-19 vaccines in older people.

Age is the strongest determinant of COVID-19 mortality, and over 2 billion people have received primary series vaccination with BNT162b2 (mRNA) or ChAdOx1 (adenoviral vector). However, the profile of sustained vaccine immunogenicity in older people is unknown. Here, we determine spike-specific humoral and cellular immunity to 8 months following BNT162b2 or ChAdOx1 in 245 people aged 80-98 years. Vaccines are strongly immunogenic, with antibodies retained in every donor, while titers fall to 23%-26% from peak. Peak immunity develops rapidly with standard interval BNT162b2, although antibody titers are enhanced 3.7-fold with extended interval. Neutralization of ancestral variants is superior following BNT162b2, while neutralization of Omicron is broadly negative. Conversely, cellular responses are stronger following ChAdOx1 and are retained to 33%-60% of peak with all vaccines. BNT162b2 and ChAdOx1 elicit strong, but differential, sustained immunogenicity in older people. These data provide a baseline to assess optimal booster regimen in this vulnerable age group.

Differential immunogenicity of BNT162b2 or ChAdOx1 vaccines after extended-interval homologous dual vaccination in older people.

BACKGROUND: Several SARS-CoV-2 vaccines have shown clinical efficacy against Covid-19 infection but there remains uncertainty about the immune responses elicited by different regimens. This is a particularly important question for older people who are at increased clinical risk following infection and in whom immune senescence may limit vaccine responses. The BNT162b2 mRNA and ChAdOx1 adenovirus vaccines were the first two vaccines deployed in the UK programme using an 8-12 week 'extended interval'. OBJECTIVES: We undertook analysis of the spike-specific antibody and cellular immune response in 131 participants aged 80+ years after the second dose of 'extended interval' dual vaccination with either BNT162b2 mRNA (n = 54) or ChAdOx1 (n = 77) adenovirus vaccine. Blood samples were taken 2-3 weeks after second vaccine and were paired with samples taken at 5-weeks after first vaccine which have been reported previously. Antibody responses were measured using the Elecsys® electrochemiluminescence immunoassay assay and cellular responses were assessed by IFN-γ ELISpot. RESULTS: Antibody responses against spike protein became detectable in all donors following dual vaccination with either vaccine. 4 donors had evidence of previous natural infection which is known to boost vaccine responses. Within the 53 infection-naïve donors the median antibody titre was 4030 U/ml (IQR 1892-8530) following BNT162b2 dual vaccination and 1405 (IQR 469.5-2543) in the 74 patients after the ChAdOx1 vaccine (p = < 0.0001). Spike-specific T cell responses were observed in 30% and 49% of mRNA and ChAdOx1 recipients respectively and median responses were 1.4-times higher in ChAdOx1 vaccinees at 14 vs 20 spots/million respectively (p = 0.022). CONCLUSION: Dual vaccination with BNT162b2 or ChAdOx1 induces strong humoral immunity in older people following an extended interval protocol. Antibody responses are 2.9-times higher following the mRNA regimen whilst cellular responses are 1.4-times higher with the adenovirus-based vaccine. Differential patterns of immunogenicity are therefore elicited from the two vaccine platforms. It will be of interest to assess the relative stability of immune responses after these homologous vaccine regimens in order to assess the potential need for vaccine boosting. Furthermore, these findings indicate that heterologous vaccine platforms may offer the opportunity to further optimize vaccine responses.

Extended interval BNT162b2 vaccination enhances peak antibody generation.

The BNT162b2 vaccine is highly effective against COVID-19 infection and was delivered with a 3-week time interval in registration studies1. However, many countries extended this interval to accelerate population coverage with a single vaccine. It is not known how immune responses are influenced by delaying the second dose. We provide the assessment of immune responses in the first 14 weeks after standard or extended-interval BNT162b2 vaccination and show that delaying the second dose strongly boosts the peak antibody response by 3.5-fold in older people. This enhanced antibody response may offer a longer period of clinical protection and delay the need for booster vaccination. In contrast, peak cellular-specific responses were the strongest in those vaccinated on a standard 3-week vaccine interval. As such, the timing of the second dose has a marked influence on the kinetics and magnitude of the adaptive immune response after mRNA vaccination in older people.

SARS-CoV-2 vaccine responses following CD20-depletion treatment in patients with haematological and rheumatological disease: a West Midlands Research Consortium study.

B-cell-depleting agents are among the most commonly used drugs to treat haemato-oncological and autoimmune diseases. They rapidly induce a state of peripheral B-cell aplasia with the potential to interfere with nascent vaccine responses, particularly to novel antigens. We have examined the relationship between B-cell reconstitution and SARS-CoV-2 vaccine responses in two cohorts of patients previously exposed to B-cell-depleting agents: a cohort of patients treated for haematological B-cell malignancy and another treated for rheumatological disease. B-cell depletion severely impairs vaccine responsiveness in the first 6 months after administration: SARS-CoV-2 antibody seroprevalence was 42.2% and 33.3% in the haemato-oncological patients and rheumatology patients, respectively and 22.7% in patients vaccinated while actively receiving anti-lymphoma chemotherapy. After the first 6 months, vaccine responsiveness significantly improved during early B-cell reconstitution; however, the kinetics of reconstitution was significantly faster in haemato-oncology patients. The AstraZeneca ChAdOx1 nCoV-19 vaccine and the Pfizer BioNTech 162b vaccine induced equivalent vaccine responses; however, shorter intervals between vaccine doses (<1 m) improved the magnitude of the antibody response in haeamto-oncology patients. In a subgroup of haemato-oncology patients, with historic exposure to B-cell-depleting agents (>36 m previously), vaccine non-responsiveness was independent of peripheral B-cell reconstitution. The findings have important implications for primary vaccination and booster vaccination strategies in individuals clinically vulnerable to SARS-CoV-2.

mRNA vaccination in people over 80 years of age induces strong humoral immune responses against SARS-CoV-2 with cross neutralization of P.1 Brazilian variant.

Age is the major risk factor for mortality after SARS-CoV-2 infection and older people have received priority consideration for COVID-19 vaccination. However, vaccine responses are often suboptimal in this age group and few people over the age of 80 years were included in vaccine registration trials. We determined the serological and cellular response to spike protein in 100 people aged 80-96 years at 2 weeks after the second vaccination with the Pfizer BNT162b2 mRNA vaccine. Antibody responses were seen in every donor with high titers in 98%. Spike-specific cellular immune responses were detectable in only 63% and correlated with humoral response. Previous SARS-CoV-2 infection substantially increased antibody responses after one vaccine and antibody and cellular responses remained 28-fold and 3-fold higher, respectively, after dual vaccination. Post-vaccine sera mediated strong neutralization of live Victoria infection and although neutralization titers were reduced 14-fold against the P.1 variant first discovered in Brazil they remained largely effective. These data demonstrate that the mRNA vaccine platform delivers strong humoral immunity in people up to 96 years of age and retains broad efficacy against the P.1 variant of concern.

Immunogenicity of single vaccination with BNT162b2 or ChAdOx1 nCoV-19 at 5-6 weeks post vaccine in participants aged 80 years or older: an exploratory analysis.

BACKGROUND: In several countries, extended interval COVID-19 vaccination regimens are now used to accelerate population coverage, but the relative immunogenicity of different vaccines in older people remains uncertain. In this study we aimed to assess the antibody and cellular responses of older people after a single dose of either the BNT162b2 vaccine (tozinameran; Pfizer-BioNTech) or ChAdOx1 nCoV-19 vaccine (Oxford University-AstraZeneca). METHODS: Participants aged 80 years or older, who did not live in a residential or care home or require assisted living, and had received a single dose of either the BNT162b2 vaccine or ChAdOx1 nCoV-19 vaccine were eligible to participate. Participants were recruited through local primary care networks in the West Midlands, UK. Blood samples and dried blood spots were taken 5-6 weeks after vaccination to assess adaptive immune responses using Elecsys electrochemiluminescence immunoassay and cellular responses by ELISpot. Primary endpoints were percentage response and quantification of adaptive immunity. FINDINGS: Between Dec 29, 2020, and Feb 28, 2021, 165 participants were recruited and included in the analysis. 76 participants had received BNT162b2 (median age 84 years, IQR 82-89; range 80-98) and 89 had received ChAdOx1 nCoV-19 (median age 84 years, 81-87; 80-99). Antibody responses against the spike protein were detectable in 69 (93%) of 74 BNT162b2 vaccine recipients and 77 (87%) of 89 ChAdOx1 nCoV-19 vaccine recipients. Median antibody titres were of 19·3 U/mL (7·4-79·4) in the BNT162b2 vaccine recipients and 19·6 U/mL (6·1-60·0) in the ChAdOx1 nCoV-19 vaccine recipients (p=0·41). Spike protein-specific T-cell responses were observed in nine (12%) of 73 BNT162b2 vaccine recipients and 27 (31%) of 88 ChAdOx1 nCoV-19 vaccine recipients, and median responses were three-times higher in ChAdOx1 nCoV-19 vaccine recipients (24 spots per 1 × 106 peripheral blood mononuclear cells) than BNT162b2 vaccine recipients (eight spots per 1 × 106 peripheral blood mononuclear cells; p<0·0001). Humoral and cellular immune responses against spike protein were correlated in both cohorts. Evidence of previous SARS-CoV-2 infection was seen in eight participants (n=5 BNT162b2 recipients and n=3 ChAdOx1 nCoV-19 recipients), and was associated with 691-times and four-times increase in humoral and cellular immune responses across the whole cohort. INTERPRETATION: Single doses of either BNT162b2 or ChAdOx1 nCoV-19 in older people induces humoral immunity in most participants, and is markedly enhanced by previous infection. Cellular responses were weaker, but showed enhancement after the ChAdOx1 nCoV-19 vaccine at the 5-6 week timepoint. FUNDING: Medical Research Council, National Institute for Health Research, and National Core Studies.

Robust antibody responses in 70-80-year-olds 3 weeks after the first or second doses of Pfizer/BioNTech COVID-19 vaccine, United Kingdom, January to February 2021.

Sera were collected from 185 adults aged ≥ 70 years in London to evaluate the immune response to COVID-19 vaccines. A single dose of Pfizer/BioNtech vaccine resulted in > 94% seropositivity after 3 weeks in naïve individuals using the Roche Spike antibody assay, while two doses produced very high spike antibody levels, significantly higher than convalescent sera from mild-to-moderate PCR-confirmed adult cases. Our findings support the United Kingdom's approach of prioritising the first dose and delaying the second dose of COVID-19 vaccine.

Outcomes of COVID-19 in patients with CLL: a multicenter international experience.

Given advanced age, comorbidities, and immune dysfunction, chronic lymphocytic leukemia (CLL) patients may be at particularly high risk of infection and poor outcomes related to coronavirus disease 2019 (COVID-19). Robust analysis of outcomes for CLL patients, particularly examining effects of baseline characteristics and CLL-directed therapy, is critical to optimally manage CLL patients through this evolving pandemic. CLL patients diagnosed with symptomatic COVID-19 across 43 international centers (n = 198) were included. Hospital admission occurred in 90%. Median age at COVID-19 diagnosis was 70.5 years. Median Cumulative Illness Rating Scale score was 8 (range, 4-32). Thirty-nine percent were treatment naive ("watch and wait"), while 61% had received ≥1 CLL-directed therapy (median, 2; range, 1-8). Ninety patients (45%) were receiving active CLL therapy at COVID-19 diagnosis, most commonly Bruton tyrosine kinase inhibitors (BTKi's; n = 68/90 [76%]). At a median follow-up of 16 days, the overall case fatality rate was 33%, though 25% remain admitted. Watch-and-wait and treated cohorts had similar rates of admission (89% vs 90%), intensive care unit admission (35% vs 36%), intubation (33% vs 25%), and mortality (37% vs 32%). CLL-directed treatment with BTKi's at COVID-19 diagnosis did not impact survival (case fatality rate, 34% vs 35%), though the BTKi was held during the COVID-19 course for most patients. These data suggest that the subgroup of CLL patients admitted with COVID-19, regardless of disease phase or treatment status, are at high risk of death. Future epidemiologic studies are needed to assess severe acute respiratory syndrome coronavirus 2 infection risk, these data should be validated independently, and randomized studies of BTKi's in COVID-19 are needed to provide definitive evidence of benefit.