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Immunity ; 54(8): 1869-1882.e6, 2021 08 10.
Article in English | MEDLINE | ID: covidwho-1293864


Vaccine-associated enhanced respiratory disease (VAERD) was previously observed in some preclinical models of severe acute respiratory syndrome (SARS) and MERS coronavirus vaccines. We used the SARS coronavirus 2 (SARS-CoV-2) mouse-adapted, passage 10, lethal challenge virus (MA10) mouse model of acute lung injury to evaluate the immune response and potential for immunopathology in animals vaccinated with research-grade mRNA-1273. Whole-inactivated virus or heat-denatured spike protein subunit vaccines with alum designed to elicit low-potency antibodies and Th2-skewed CD4+ T cells resulted in reduced viral titers and weight loss post challenge but more severe pathological changes in the lung compared to saline-immunized animals. In contrast, a protective dose of mRNA-1273 induced favorable humoral and cellular immune responses that protected from viral replication in the upper and lower respiratory tract upon challenge. A subprotective dose of mRNA-1273 reduced viral replication and limited histopathological manifestations compared to animals given saline. Overall, our findings demonstrate an immunological signature associated with antiviral protection without disease enhancement following vaccination with mRNA-1273.

COVID-19 Vaccines/immunology , COVID-19/immunology , COVID-19/prevention & control , Host-Pathogen Interactions/immunology , SARS-CoV-2/immunology , Vaccines, Synthetic/immunology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Biopsy , COVID-19 Vaccines/administration & dosage , Disease Models, Animal , Humans , Immunoglobulin G , Immunohistochemistry , Mice , Outcome Assessment, Health Care , RNA, Messenger , Spike Glycoprotein, Coronavirus/immunology , T-Lymphocyte Subsets/immunology , T-Lymphocyte Subsets/metabolism , Vaccines, Synthetic/administration & dosage
N Engl J Med ; 383(20): 1920-1931, 2020 11 12.
Article in English | MEDLINE | ID: covidwho-971502


BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in late 2019 and spread globally, prompting an international effort to accelerate development of a vaccine. The candidate vaccine mRNA-1273 encodes the stabilized prefusion SARS-CoV-2 spike protein. METHODS: We conducted a phase 1, dose-escalation, open-label trial including 45 healthy adults, 18 to 55 years of age, who received two vaccinations, 28 days apart, with mRNA-1273 in a dose of 25 µg, 100 µg, or 250 µg. There were 15 participants in each dose group. RESULTS: After the first vaccination, antibody responses were higher with higher dose (day 29 enzyme-linked immunosorbent assay anti-S-2P antibody geometric mean titer [GMT], 40,227 in the 25-µg group, 109,209 in the 100-µg group, and 213,526 in the 250-µg group). After the second vaccination, the titers increased (day 57 GMT, 299,751, 782,719, and 1,192,154, respectively). After the second vaccination, serum-neutralizing activity was detected by two methods in all participants evaluated, with values generally similar to those in the upper half of the distribution of a panel of control convalescent serum specimens. Solicited adverse events that occurred in more than half the participants included fatigue, chills, headache, myalgia, and pain at the injection site. Systemic adverse events were more common after the second vaccination, particularly with the highest dose, and three participants (21%) in the 250-µg dose group reported one or more severe adverse events. CONCLUSIONS: The mRNA-1273 vaccine induced anti-SARS-CoV-2 immune responses in all participants, and no trial-limiting safety concerns were identified. These findings support further development of this vaccine. (Funded by the National Institute of Allergy and Infectious Diseases and others; mRNA-1273 number, NCT04283461).

Coronavirus Infections/prevention & control , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , RNA, Messenger/immunology , Spike Glycoprotein, Coronavirus/immunology , Viral Vaccines/therapeutic use , Adult , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Antibody Formation , Betacoronavirus , COVID-19 , COVID-19 Vaccines , Female , Humans , Immunization, Secondary , Male , SARS-CoV-2 , T-Lymphocytes/immunology , Viral Vaccines/adverse effects , Young Adult