ABSTRACT
BackgroundKidney transplant recipients (KTR) have a diminished response to SARS-CoV-2 vaccination in comparison to immunocompetent individuals. Deeper understanding of the antibody response in KTRs following third-dose vaccination would enable identification of those who remain unprotected against Omicron and require additional treatment strategies. MethodsWe profiled antibody responses in KTRs pre- and at one and three months post-third-dose SARS-CoV2 mRNA-based vaccine. Anti-spike and anti-RBD IgG levels were determined by ELISA. Neutralization against wild-type, Beta, Delta and Omicron (BA.1) variants was determined using a SARS-CoV-2 spike pseudotyped lentivirus assay. Results44 KTRs were analysed at 1 and 3 months (n=26) post-third-dose. At one month, the proportion of participants with a robust antibody response had increased significantly from baseline, but Omicron-specific neutralizing antibodies were detected in just 45% of KTRs. Median binding antibody levels declined at 3 months, but the proportion of KTRs with a robust antibody response was unchanged. 38.5% KTRs maintained Omicron-specific neutralization at 3 months. No clinical variables were significantly associated with detectable Omicron neutralizing antibodies, but anti-RBD titres appeared to identify those with Omicron-specific neutralizing capacity. ConclusionOver 50% of KTRs lack an Omicron-specific neutralization response 1 month following a third mRNA-vaccine dose. Among responders, binding and neutralizing antibody responses were well preserved at 3 months. Anti-RBD antibody titres may be a useful identifier of patients with detectable Omicron neutralizing antibody response. Trial registrationClinical Trials Ontario: ID 3604 FundingFunded by the St. Michaels Hospital Foundation (CMM, DAY) and the Public Health Agency of Canada, through the COVID-19 Immunity Task Force (MAH, MJO, AL).
ABSTRACT
PTX-COVID19-B mRNA vaccine encodes for SARS-CoV-2 Spike protein G614 variant and lacks the proline-proline (986-987 position) mutation present in other COVID-19 vaccines. This Phase 1 observer-blinded, randomized, placebo-controlled, ascending dose study evaluated the safety, tolerability, and immunogenicity of two doses of PTX-COVID19-B vaccine in healthy seronegative adults. Participants received two intramuscular doses, 4 weeks apart, of 16-g, 40-g, or 100-g PTX-COVID19-B. Adverse events were generally mild to moderate, self-resolving, and transient. The most common solicited local and systemic adverse event was pain at the injection site and headache, respectively. After the first immunization, all participants seroconverted, producing high titers of anti-receptor-binding-domain, anti-Spike, and neutralizing antibodies, including neutralizing antibodies against the ancestral viral strain and the Alpha, Beta, and Delta variants of concern, in a dose-dependent way, further increasing over 10-20 times after the second dose. All tested doses of PTX-COVID19-B were safe, well-tolerated, and provided a strong immunogenicity response. The 40-g dose showed fewer adverse reactions than the 100-g dose, supporting further investigation of the 40-g dose. Clinical Trial RegistrationClinicalTrials.gov identifier: NCT04765436 (https://clinicaltrials.gov/ct2/show/NCT04765436)
ABSTRACT
BackgroundLimited information is available on the impact of immunosuppressants on COVID-19 vaccination in patients with immune-mediated inflammatory diseases (IMID). MethodsThis observational cohort study examined the immunogenicity of SARS-CoV-2 mRNA vaccines in adult patients with inflammatory bowel disease, rheumatoid arthritis, ankylosing spondylitis, or psoriatic disease, with or without maintenance immunosuppressive therapies. Antibody and T cell responses to SARS-COV-2, including neutralization against SARS-CoV-2 variants were determined before and after 1 and 2 vaccine doses. ResultsWe prospectively followed 150 subjects, 26 healthy controls, 9 IMID patients on no treatment, 44 on anti-TNF, 16 on anti-TNF with methotrexate/azathioprine (MTX/AZA), 10 on anti-IL-23, 28 on anti-IL-12/23, 9 on anti-IL-17, and 8 on MTX/AZA. Antibody and T cell responses to SARS-CoV-2 were detected in all participants, increasing from dose 1 to dose 2 and declining 3 months later, with greater attrition in IMID patients compared to healthy controls. Antibody levels and neutralization efficacy against variants of concern were substantially lower in anti-TNF treated patients than in healthy controls and were undetectable against Omicron by 3 months after dose 2. ConclusionsOur findings support the need for a third dose of mRNA vaccine and for continued monitoring of immunity in these patient groups. FundingFunded by a donation from Juan and Stefania Speck and by Canadian Institutes of Health (CIHR) /COVID-Immunity Task Force (CITF) grants VR-1 172711 and VS1-175545 (T.H.W. and A.C.G); CIHR FDN-143250 (T.H.W.), GA2-177716 (V.C., A.C.G., T.W.), GA1-177703 (A.C.G.) and the CIHR rapid response network to SARS-CoV-2 variants, CoVaRR-Net (to A.C.G.).
ABSTRACT
Prioritizing Ontarios long-term care home (LTCH) residents for vaccination against severe acute respiratory syndrome coronavirus 2 has drastically reduced their disease burden; however, recent LTCH outbreaks of variants of concern (VOCs) have raised questions regarding their immune responses. In 198 residents, mRNA vaccine dose 1 elicited partial spike and receptor binding domain antibody responses, while the second elicited a response at least equivalent to convalescent individuals in most residents. Residents administered mRNA-1273 (Moderna) mounted stronger total and neutralizing antibody responses than those administered BNT162b2 (Pfizer-BioNTech). Two to four weeks after dose 2, residents (n = 119, median age 88) produced 4.8-6.3-fold fewer neutralizing antibodies than staff (n = 78; median age 47) against wild-type (with D614G) pseudotyped lentivirus, and residents administered BNT162b2 produced 3.89-fold fewer neutralizing antibodies than those who received mRNA-1273. These effects were exacerbated upon serum challenge with pseudotyped VOC spike, with up to 7.94-fold reductions in B.1.351 (Beta) neutralization. Cumulatively, weaker vaccine stimulation, age/comorbidities, and the VOC produced an [~]130-fold reduction in apparent neutralization titers in LTCH residents and 37.9% of BNT162b2-vaccinated residents had undetectable neutralizing antibodies to B.1.351. Continued immune response surveillance and additional vaccine doses may be required in this population with known vulnerabilities.
ABSTRACT
Safe and effective vaccines are needed to end the COVID-19 pandemic caused by SARS-CoV-2. Here we report the preclinical development of a lipid nanoparticle (LNP) formulated SARS-CoV-2 mRNA vaccine, PTX-COVID19-B. PTX-COVID19-B was chosen among three candidates after the initial mouse vaccination results showed that it elicited the strongest neutralizing antibody response against SARS-CoV-2. Further tests in mice and hamsters indicated that PTX-COVID19-B induced robust humoral and cellular immune responses and completely protected the vaccinated animals from SARS-CoV-2 infection in the lung. Studies in hamsters also showed that PTX-COVID19-B protected the upper respiratory tract from SARS-CoV-2 infection. Mouse immune sera elicited by PTX-COVID19-B vaccination were able to neutralize SARS-CoV-2 variants of concern (VOCs), including the B.1.1.7, B.1.351 and P.1 lineages. No adverse effects were induced by PTX-COVID19-B in both mice and hamsters. These preclinical results indicate that PTX-COVID19-B is safe and effective. Based on these results, PTX-COVID19-B was authorized by Health Canada to enter clinical trials in December 2020 with a phase 1 clinical trial ongoing (ClinicalTrials.gov number: NCT04765436). One Sentence SummaryPTX-COVID19-B is a SARS-CoV-2 mRNA vaccine that is highly immunogenic, safe, and effective in preventing SARS-CoV-2 infection in mice and hamsters and is currently being evaluated in human clinical trials.
