Common Variable Immunodeficiency Disorders as a Model for Assessing COVID-19 Vaccine Responses in Immunocompromised Patients

Soluble wild-type ACE2 molecules inhibit newer SARS-CoV-2 variants and are a potential antiviral strategy to mitigate disease severity in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease of 2019 (COVID-19), has caused havoc around the world. While several COVID-19 vaccines and drugs have been authorized for use, these antiviral drugs remain beyond the reach of most low- and middle-income countries. Rapid viral evolution is reducing the efficacy of vaccines and monoclonal antibodies and contributing to the deaths of some fully vaccinated persons. Others with normal immunity may have chosen not to be vaccinated and remain at risk if they contract the infection. Vaccines may not protect some immunodeficient patients from SARS-CoV-2, who are also at increased risk of chronic COVID-19 infection, a dangerous stalemate between the virus and a suboptimal immune response. Intra-host viral evolution could rapidly lead to the selection and dominance of vaccine and monoclonal antibody-resistant clades of SARS-CoV-2. There is thus an urgent need to develop new treatments for COVID-19. The NZACE2-Pātari project, comprising modified soluble angiotensin-converting enzyme 2 (ACE2) molecules, seeks to intercept and block SARS-CoV-2 infection of the respiratory mucosa. In vitro data presented here show that soluble wild-type ACE2 molecules retain the ability to effectively block the Spike (S) glycoprotein of SARS-CoV-2 variants including the ancestral Wuhan, delta (B.1.617.2) and omicron (B.1.1.529) strains. This therapeutic strategy may prove effective if implemented early during the nasal phase of the infection and may act synergistically with other antiviral drugs such as Paxlovid to further mitigate disease severity.

Durable immunity to SARS-CoV-2 in both lower and upper airways achieved with a gorilla adenovirus (GRAd) S-2P vaccine in non-human primates

SARS-CoV-2 continues to pose a global threat, and current vaccines, while effective against severe illness, fall short in preventing transmission. To address this challenge, there's a need for vaccines that induce mucosal immunity and can rapidly control the virus. In this study, we demonstrate that a single immunization with a novel gorilla adenovirus-based vaccine (GRAd) carrying the pre-fusion stabilized Spike protein (S-2P) in non-human primates provided protective immunity for over one year against the BA.5 variant of SARS-CoV-2. A prime-boost regimen using GRAd followed by adjuvanted S-2P (GRAd+S-2P) accelerated viral clearance in both the lower and upper airways. GRAd delivered via aerosol (GRAd(AE)+S-2P) modestly improved protection compared to its matched intramuscular regimen, but showed dramatically superior boosting by mRNA and, importantly, total virus clearance in the upper airway by day 4 post infection. GrAd vaccination regimens elicited robust and durable systemic and mucosal antibody responses to multiple SARS-CoV-2 variants, but only GRAd(AE)+S-2P generated long-lasting T cell responses in the lung. This research underscores the flexibility of the GRAd vaccine platform to provide durable immunity against SARS-CoV-2 in both the lower and upper airways.

SARS-CoV-2 Omicron: Light at the End of the Long Pandemic Tunnel or Another False Dawn for Immunodeficient Patients?

COVID-19 has had a disastrous impact on the world. Apart from at least 6 million deaths, countless COVID-19 survivors are suffering long-term physical and psychiatric morbidity. Hundreds of millions have been plunged into poverty caused by economic misery, particularly in developing nations. Early in the pandemic, it became apparent certain groups of individuals such as the elderly and those with comorbidities were more likely to suffer severe disease. In addition, patients with some forms of immunodeficiency, including those with T-cell and innate immune defects, were at risk of poor outcomes. Patients with immunodeficiencies are also disadvantaged as they may not respond optimally to COVID-19 vaccines and often have pre-existing lung damage. SARS-CoV-2 Omicron (B.1.529) and its subvariants (BA.1, BA.2, etc) have emerged recently and are dominating COVID-19 infections globally. Omicron is associated with a reduced risk of hospitalization and appears to have a lower case fatality rate compared with previous SARS-CoV-2 variants. Omicron has offered hope the pandemic may finally be coming to an end, particularly for vaccinated, healthy individuals. The situation is less clear for individuals with vulnerabilities, particularly immunodeficient patients. This perspective offers insight into potential implications of the SARS-CoV-2 Omicron variant for patients with immunodeficiencies.

Humoral response to mRNA vaccines against SARS-CoV-2 in patients with humoral immunodeficiency disease

OBJECTIVES

Although mRNA-based vaccines against SARS-CoV-2 induce a robust immune response and prevent infections and hospitalizations, there are limited data on the antibody response in individuals with humoral immunodeficiency. The aim of this study was to evaluate the humoral immune response after two vaccine doses with BNT162b2 or mRNA-1273 in patients with humoral immunodeficiency disease.

METHODS

This cross-sectional study assessed 39 individuals with hypogammaglobulinemia under immunoglobulin replacement therapy. IgG anti-SARS-CoV-2 spike protein antibodies (anti-S) were measured 4 weeks to 4 months after two doses of an mRNA vaccine against SARS-CoV-2. The proportion of patients, who developed a humoral immune response to the spike protein were evaluated and compared to 19 healthy controls.

RESULTS

After vaccination with two vaccine doses, 26/39 patients (66.7%) with humoral immunodeficiency disease and all healthy controls developed anti-S. In subjects with baseline IgG <3 g/l, only 1/5 (20%) showed a humoral immune response. 10 out of 26 with CVID (38.5%) and 7/9 under immunosuppressive drugs (77.8%) developed no immune response (13 subjects with no response) compared to 0/19 in healthy controls. Subgroup analysis in patients without immunosuppressive drugs revealed lower anti-S in patients with moderate to severe humoral immunodeficiency disease: baseline IgG <3 g/l: 12.0 AU/ml (95%CI 12.0-125.0), baseline IgG 3-5 g/l: 99.9 AU/ml (95%CI 14.4-400.0), baseline IgG >5 g/l: 151.5 AU/ml (95%CI 109.0-400.0), healthy controls 250.0 AU/ml (95%CI 209.0-358.0), p = 0.007.

CONCLUSION

In most patients with mild to moderate humoral immunodeficiency we found only slightly lower anti-S antibodies compared with healthy controls after two vaccine doses with BNT162b2 and mRNA-1273. However, in patients with a decreased baseline IgG below 3 g/l and/or under immunosuppressive drugs, we found severely impaired humoral immune responses.

Severe COVID-19 is a T cell immune dysregulatory disorder triggered by SARS-CoV-2

INTRODUCTION

COVID-19 has had a calamitous impact on the global community. Apart from at least 6M deaths, hundreds of millions have been infected and a much greater number have been plunged into poverty. Vaccines have been effective but financial and logistical challenges have hampered their rapid global deployment. Vaccine disparities have allowed the emergence of new SARS-CoV-2 variants including delta and omicron, perpetuating the pandemic.

AREAS COVERED

The immunological response to SARS-CoV-2 has been the subject of intense study and is now better understood. Many of the clinical manifestations of severe disease are a consequence of immune dysregulation triggered by the virus. This may explain the lack of efficacy of antiviral treatments such as convalescent plasma infusions, given later in the disease.

EXPERT OPINION

T cells play a crucial role in both the outcome of COVID-19 as well as the protective response to vaccines. Vaccines do not prevent infection but reduce the risk of a chaotic and destructive cellular immune response to the virus. Severe COVID-19 should be considered a virus-induced secondary immune dysregulatory disorder of cellular immunity, with broad host susceptibility. This perspective of COVID-19 will lead to better diagnostic tests, vaccines and therapeutic strategies in the future.