Cambridge, Mass.-based Moderna’s study, published in The New England Journal of Medicine, showed that a two-dose vaccination schedule of the mRNA-1273 vaccine candidate led to a “robust immune response and protection” against SARS-CoV-2 infection in the upper and lower airways in non-human primates.
Additionally, there was no evidence of vaccine-associated enhanced respiratory disease (VAERD) in the primates, according to a news release.
The study assessed immunogenicity and protective efficacy after a two-dose vaccination schedule of 10 µg or 100 µg doses of mRNA-1273 or control given four weeks apart. Then, four weeks after the second vaccination, animals were challenged with high doses of SARS-CoV-2 through intranasal and intratracheal routes.
Moderna said the immune response observed in the non-human study was consistent with the recently touted Phase 1 human study, with the company having previously reported positive results in May for Phase 1. Yesterday, the company announced the launch of Phase 3 of the human study.
Vaccination reportedly led to a significant increase in the primates’ T cell responses, primarily Th1 CD4 T cells, while a further increase in neutralizing antibody titers was observed at the higher dose in the non-human primates. Two doses of mRNA-1273 also provided protection against lung inflammation at both dose levels and both groups demonstrated protection against viral replication in the lungs, while the higher dose protected against viral replication in the nose of the animals, too.
Notably, none of the eight animals in the high-dose group showed detectable viral replication in the nose, compared to six out of eight in the placebo group on day two.
“This important preclinical study shows that mRNA-1273 protected against a high dose SARS-CoV-2 infection in non-human primates and prevented pulmonary disease in all animals, further supporting the clinical advancement of mRNA-1273,” Moderna president Dr. Stephen Hoge said in the news release. “We believe this is the first demonstration of control of viral replication within two days of challenge in both the nose and lungs in non-human primates by a vaccine against COVID-19.
“Given the similarity between the protective immune response generated by mRNA-1273 in this study and the immune response seen in humans in the recently published Phase 1 clinical data for the vaccine, we remain cautiously optimistic that mRNA-1273 will be able to prevent COVID-19 disease and may also slow the spread of SARS-CoV-2 by shortening the duration of shedding.”