SARS-CoV-2 Vaccine Responses in Individuals with Antibody Deficiency: Findings from the COV-AD Study

BACKGROUND

Vaccination prevents severe morbidity and mortality from COVID-19 in the general population. The immunogenicity and efficacy of SARS-CoV-2 vaccines in patients with antibody deficiency is poorly understood.

OBJECTIVES

COVID-19 in patients with antibody deficiency (COV-AD) is a multi-site UK study that aims to determine the immune response to SARS-CoV-2 infection and vaccination in patients with primary or secondary antibody deficiency, a population that suffers from severe and recurrent infection and does not respond well to vaccination.

METHODS

Individuals on immunoglobulin replacement therapy or with an IgG less than 4 g/L receiving antibiotic prophylaxis were recruited from April 2021. Serological and cellular responses were determined using ELISA, live-virus neutralisation and interferon gamma release assays. SARS-CoV-2 infection and clearance were determined by PCR from serial nasopharyngeal swabs.

RESULTS

A total of 5.6% (n = 320) of the cohort reported prior SARS-CoV-2 infection, but only 0.3% remained PCR positive on study entry. Seropositivity, following two doses of SARS-CoV-2 vaccination, was 54.8% (n = 168) compared with 100% of healthy controls (n = 205). The magnitude of the antibody response and its neutralising capacity were both significantly reduced compared to controls. Participants vaccinated with the Pfizer/BioNTech vaccine were more likely to be seropositive (65.7% vs. 48.0%, p = 0.03) and have higher antibody levels compared with the AstraZeneca vaccine (IgGAM ratio 3.73 vs. 2.39, p = 0.0003). T cell responses post vaccination was demonstrable in 46.2% of participants and were associated with better antibody responses but there was no difference between the two vaccines. Eleven vaccine-breakthrough infections have occurred to date, 10 of them in recipients of the AstraZeneca vaccine.

CONCLUSION

SARS-CoV-2 vaccines demonstrate reduced immunogenicity in patients with antibody deficiency with evidence of vaccine breakthrough infection.

Increased Seroprevalence and Improved Antibody Responses Following Third Primary SARS-CoV-2 Immunisation: An Update From the COV-AD Study

Background

Patients with primary and secondary antibody deficiency are vulnerable to COVID-19 and demonstrate diminished responses following two-dose SARS-CoV-2 vaccine schedules. Third primary vaccinations have been deployed to enhance their humoral and cellular immunity.

Objectives

To determine the immunogenicity of the third primary SARS-CoV-2 immunisation in a heterogeneous cohort of patients with antibody deficiency.

Methods

Participants enrolled in the COV-AD study were sampled before and after their third vaccine dose. Serological and cellular responses were determined using ELISA, live-virus neutralisation and ELISPOT assays.

Results

Following a two-dose schedule, 100% of healthy controls mounted a serological response to SARS-CoV-2 vaccination, however, 38.6% of individuals with antibody deficiency remained seronegative. A third primary SARS-CoV-2 vaccine significantly increased anti-spike glycoprotein antibody seroprevalence from 61.4% to 76.0%, the magnitude of the antibody response, its neutralising capacity and induced seroconversion in individuals who were seronegative after two vaccine doses. Vaccine-induced serological responses were broadly cross-reactive against the SARS-CoV-2 B.1.1.529 variant of concern, however, seroprevalence and antibody levels remained significantly lower than healthy controls. No differences in serological responses were observed between individuals who received AstraZeneca ChAdOx1 nCoV-19 and Pfizer BioNTech 162b2 during their initial two-dose vaccine schedule. SARS-CoV-2 infection-naive participants who had received a heterologous vaccine as a third dose were significantly more likely to have a detectable T cell response following their third vaccine dose (61.5% vs 11.1%).

Conclusion

These data support the widespread use of third primary immunisations to enhance humoral immunity against SARS-CoV-2 in individuals with antibody deficiency.

Prevention and treatment of venous thromboembolism in hospital and the community: a research programme including the ExACT RCT

Background

Deep-vein thrombosis and pulmonary embolism, collectively known as venous thromboembolism when clots are formed in the venous circulation, are common disorders that are often unprovoked (i.e. there is no obvious reason for the clot occurring). Some people, after having an unprovoked clot, are at a high risk of developing another, or at risk of developing a secondary clot, most importantly in the lungs. Furthermore, in the long term, some patients will develop circulation problems known as post-thrombotic syndrome. The aim of this programme was to improve the understanding of both the prevention and the treatment of thrombosis in people at the highest risk of recurrence.

Objectives

To clarify if it is possible to identify those people at the highest risk of having a recurrent venous thromboembolism, and if it is possible to prevent this happening by giving anticoagulation treatment for longer. To clarify if it is possible to identify those people at the highest risk of developing post-thrombotic syndrome. To document the current knowledge level about prevention and treatment of venous thromboembolism. To find what the barriers are to implementing measures to prevent venous thromboembolism. To find the most cost-effective means of treating venous thromboembolism.

Design

Mixed methods, comprising a randomised controlled trial, qualitative studies, cost-effectiveness analyses and questionnaire studies, including patient preferences.

Setting

UK general practices and hospitals, predominantly from the Midlands and Shropshire.

Participants

Adults attending participating anticoagulation clinics with a diagnosis of first unprovoked deep-vein thrombosis or pulmonary embolism, and health-care professionals, patients and other stakeholders who were involved in the prevention and treatment of venous thromboembolism.

Intervention

Extended treatment with oral anticoagulation therapy (2 years) versus standard care (treatment with oral anticoagulation therapy for at least 3 months).

Results

Work package 1 demonstrated that extended anticoagulation for up to 2 years was clinically effective and cost-effective in reducing the incidence of recurrent venous thromboembolism, with a small increase in the risk of bleeding. There was no difference in post-thrombotic syndrome incidence or severity, or quality of life, between those undergoing the extended treatment and those receiving the standard care. Work package 2 identified five common themes with regard to the prevention of hospital-acquired thrombosis: communication, knowledge, role of primary care, education and training, and barriers to patient adherence. Work package 3 suggested that extended anticoagulation with novel oral anticoagulants was cost-effective only at the £20,000-per-quality-adjusted life-year level for a recurrence rate of between 17.5% and 22.5%, depending on drug acquisition costs, while identifying a strong patient preference for extended anticoagulation based on a fear of recurrent venous thromboembolism.

Limitations

The major limitation was the failure to reach the planned recruitment target for work package 1.

Conclusions

Extended anticoagulation with warfarin for a first unprovoked venous thromboembolism is clinically effective and cost-effective and is strongly preferred by patients to the alternative of not having treatment. There are significant barriers to the implementation of preventative measures for hospital-acquired thrombosis. Further research is required on identifying patients in whom it is safe to discontinue anticoagulation, and at what time point following a first unprovoked venous thromboembolism this should be done.

Trial registration

Current Controlled Trials ISRCTN73819751 and EudraCT 2101-022119-20.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 8, No. 5. See the NIHR Journals Library website for further project information.

A randomised controlled trial of extended anticoagulation treatment versus standard treatment for the prevention of recurrent venous thromboembolism (VTE) and post-thrombotic syndrome in patients being treated for a first episode of unprovoked VTE (the ExACT study)

Venous thromboembolism (VTE) is prevalent and impactful, with a risk of death, morbidity and recurrence. Post-thrombotic syndrome (PTS) is a common consequence and associated with impaired quality of life (QoL). The ExACT study was a non-blinded, prospective, multicentred randomised controlled trial comparing extended versus limited duration anticoagulation following a first unprovoked VTE (proximal deep vein thrombosis or pulmonary embolism). Adults were eligible if they had completed ≥3 months anticoagulation (remaining anticoagulated). The primary outcome was time to first recurrent VTE from randomisation. The secondary outcomes included PTS severity, bleeding, QoL and D-dimers. Two-hundred and eighty-one patients were recruited, randomised and followed up for 24 months (mean age 63, male:female 2:1). There was a significant reduction in recurrent VTE for patients receiving extended anticoagulation [2·75 vs. 13·54 events/100 patient years, adjusted hazard ratio (aHR) 0·20 (95% confidence interval (CI): 0·09 to 0·46, P < 0·001)] with a non-significant increase in major bleeding [3·54 vs. 1·18 events/100 patient years, aHR 2·99 (95% CI: 0·81-11·05, P = 0·10)]. Outcomes of PTS and QoL were no different between groups. D-dimer results (on anticoagulation) did not predict VTE recurrence. In conclusion, extended anticoagulation reduced VTE recurrence but did not reduce PTS or improve QoL and was associated with a non-significant increase in bleeding. Results also suggest very limited clinical utility of D-dimer testing on anticoagulated patients.