Bivalent and Monovalent SARS-CoV-2 Variant Vaccine Boosters Improve coverage of the known Antigenic Landscape: Results of the COVID-19 Variant Immunologic Landscape (COVAIL) Trial (preprint)

Vaccine protection against COVID-19 wanes over time and has been impacted by the emergence of new variants with increasing escape of neutralization. The COVID-19 Variant Immunologic Landscape (COVAIL) randomized clinical trial (clinicaltrials.gov NCT 05289037) compares the breadth, magnitude and durability of antibody responses induced by a second COVID-19 vaccine boost with mRNA (Moderna mRNA-1273 and Pfizer-BioNTech BNT162b2), or adjuvanted recombinant protein (Sanofi CoV2 preS DTM-AS03) monovalent or bivalent vaccine candidates targeting ancestral and variant SARS-CoV-2 spike antigens (Beta, Delta and Omicron BA.1). We found that boosting with a variant strain is not associated with loss in neutralization against the ancestral strain. However, while variant vaccines compared to the prototype/wildtype vaccines demonstrated higher neutralizing activity against Omicron BA.1 and BA.4/5 subvariants for up to 3 months after vaccination, neutralizing activity was lower for more recent Omicron subvariants. Our study, incorporating both antigenic distances and serologic landscapes, can provide a framework for objectively guiding decisions for future vaccine updates.

Reactogenicity, Safety, and Serological and Cellular Immunogenicity of a Booster Dose of SARS-CoV-2 mRNA Prototype, Variant, and Bivalent Vaccines (preprint)

Waning immunity after two SARS-CoV-2 mRNA vaccinations and the emergence of variants precipitated the need for booster doses. We evaluated safety and serological and cellular immunogenicity through 6 months after a third mRNA vaccination in adults who received the mRNA-1273 primary series in the Phase 1 trial approximately 9 to 10 months earlier. The booster vaccine formulations included 100 mcg of mRNA-1273, 50 mcg of mRNA-1273.351 that encodes Beta variant spike protein, and bivalent vaccine of 25 mcg each of mRNA-1273 and mRNA-1273.351. A third dose of mRNA vaccine appeared safe with acceptable reactogenicity. Vaccination induced rapid increases in binding and neutralizing antibody titers to D614G, Beta, Delta and Omicron variants that persisted through 6 months post-boost, particularly after administration of Beta-containing vaccines. Spike-specific CD4 + and CD8 + T cells increased to levels similar to those following the second dose. Boost vaccination induced broad and durable humoral and T cell responses. ClinicalTrials.gov numbers NCT04283461 (mRNA-1273 Phase 1) and NCT04785144 (mRNA-1273.351 Phase 1)

Reported Cases of Multisystem Inflammatory Syndrome in Children Aged 12 to 20 Years in the United States Who Received COVID-19 Vaccine, December 2020 through August 2021 (preprint)

BackgroundMultisystem inflammatory syndrome in children (MIS-C) is a hyperinflammatory condition associated with antecedent SARS-CoV-2 infection. In the United States, reporting of MIS-C after vaccination is required under COVID-19 vaccine emergency use authorizations. This case series describes persons aged 12-20 years with MIS-C following COVID-19 vaccination reported to passive surveillance systems or through clinician outreach to CDC. MethodsWe investigated potential cases of MIS-C after COVID-19 vaccination reported to CDCs health department-based national MIS-C surveillance, the Vaccine Adverse Event Reporting System (VAERS, co-administered by CDC and the U.S. FDA), and CDCs Clinical Immunization Safety Assessment Project (CISA) from December 14, 2020, to August 31, 2021. We describe cases meeting the CDC MIS-C case definition. Any positive SARS-CoV-2 serology test satisfied the case criteria although anti-nucleocapsid antibody indicates SARS-CoV-2 infection, while anti-spike protein antibody indicates either infection or COVID-19 vaccination. FindingsWe identified 21 persons with MIS-C after COVID-19 vaccination. Of these 21 persons, median age was 16 years (range, 12-20 years); 13 (62%) were male. All were hospitalized; 12 (57%) had intensive care unit admission, and all were discharged home. Fifteen (71%) of the 21 had laboratory evidence of past or recent SARS-CoV-2 infection, and six (29%) did not. Through August 2021, 21,335,331 persons aged 12-20 years had received [≥]1 dose of COVID-19 vaccine, making the overall reporting rate for MIS-C following vaccination 1{middle dot}0 case per million persons receiving [≥]1 vaccine dose in this age group. The reporting rate for those without evidence of SARS-CoV-2 infection was 0{middle dot}3 cases per million vaccinated persons. InterpretationIn our case series, we describe a small number of persons with MIS-C who had received [≥]1 COVID-19 vaccine dose before illness onset. Continued reporting of potential cases and surveillance for MIS-C illnesses after COVID-19 vaccination is warranted. FundingThis work was supported by the Centers for Disease Control and Prevention Clinical Immunization Safety Assessment (CISA] Project contracts 200-2012-50430-0005 to Vanderbilt University Medical Center and 200-2012-53661 to Cincinnati Childrens Hospital Medical Center. Research in context panelO_ST_ABSEvidence before this studyC_ST_ABSMultisystem inflammatory syndrome in children (MIS-C), also known as paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS), is an uncommon, but serious, complication described after SARS-CoV-2 infection that is characterized by a generalized hyperinflammatory response. A review of the literature using PubMed identified reports of six persons aged 12-20 years who developed MIS-C following COVID-19 vaccination. Search terms used to identify these reports were: "multisystem inflammatory syndrome in children", "MIS-C", "MISC", "multisystem inflammatory syndrome in adults", "MIS-A", "MISA", "paediatric inflammatory multisystem syndrome", and "PIMS-TS" each with any COVID-19 vaccine type. There were no exclusion criteria (i.e., all ages and languages). Added value of this studyWe conducted integrated surveillance for MIS-C after COVID-19 vaccination using two passive surveillance systems, CDCs MIS-C national surveillance and the Vaccine Adverse Event Reporting System (VAERS), and clinician or health department outreach to CDC, including through Clinical Immunization Safety Assessment (CISA) Project consultations. We investigated reports of potential MIS-C occurring from December 14, 2020, to August 31, 2021, in persons aged 12-20 years any time after receipt of COVID-19 vaccine to identify those that met the CDC MIS-C case definition. Any positive serology test was accepted as meeting the CDC MIS-C case definition, although anti- nucleocapsid antibody is indicative of SARS-CoV-2 infection, while anti-spike protein antibody may be induced either by SARS-CoV-2 infection or by COVID-19 vaccination. We investigated 47 reports and identified 21 persons with MIS-C after receipt of COVID-19 vaccine. Of the 21 persons with MIS-C, median age was 16 years (range 12-20 years), and 13 (62%) were male. Fifteen (71%) had laboratory evidence of past or recent SARS-CoV-2 infection (positive SARS-CoV-2 nucleic acid amplification test [NAAT], viral antigen, or serology test before or during MIS-C illness evaluation), and 5 (33%) of those 15 had illness onset after their second vaccine dose. Six (29%) of 21 persons had no laboratory evidence of past or recent SARS-CoV-2 infection, and five of those six (83%) had onset of MIS-C after the second vaccine dose. Implications of all the available evidenceDuring the first nine months of the COVID-19 vaccination program in the United States, >21 million persons aged 12 to 20 years received [≥]1 dose of COVID-19 vaccine as of August 31, 2021. This case series describes MIS-C in 21 persons following vaccine receipt during this time period; the majority of persons reported also had evidence of SARS-CoV-2 infection. The surveillance has limitations, but our findings suggest that MIS-C as identified in this report following COVID-19 vaccination is rare. In evaluating persons with a clinical presentation consistent with MIS-C after COVID-19 vaccination it is important to consider alternative diagnoses, and anti-nucleocapsid antibody testing may be helpful. Continued surveillance for MIS-C illness after COVID-19 vaccination is warranted, especially as pediatric COVID-19 vaccination expands. Providers are encouraged to report potential MIS-C cases after COVID-19 vaccination to VAERS.

Safety and Immunogenicity of a Third Dose of SARS-CoV-2 mRNA Vaccine — An Interim Analysis (preprint)

Waning immunity after two SARS-CoV-2 mRNA vaccinations and the emergence of variants precipitated the need for a third dose of vaccine. We evaluated early safety and immunogenicity after a third mRNA vaccination in adults who received the mRNA-1273 primary series in the Phase 1 trial approximately 9 to 10 months earlier. The booster vaccine formulations included 100 mcg of mRNA-1273, 50 mcg of mRNA-1273.351 that encodes Beta variant spike protein, and bivalent vaccine of 25 mcg each of mRNA-1273 and mRNA-1273.351. A third dose of mRNA vaccine appeared safe with acceptable reactogenicity. Vaccination induced rapid increases in binding and neutralizing antibody titers to D614G, Beta, and Delta variants that were similar or greater than peak responses after the second dose. Spike-specific CD4+ and CD8+ T cells increased to similar levels as after the second dose. A third mRNA vaccination was well tolerated and generated robust humoral and T cell responses. ClinicalTrials.gov numbers NCT04283461 (mRNA-1273 Phase 1) and NCT04785144 (mRNA-1273.351 Phase 1)