Pharmaceutical group Moderna’s investigational vaccine mRNA-1273, which is currently in clinical stage, has protected mice from the SARS-CoV-2 infection that causes Covid-19.
The findings, published in the journal Nature, show that the investigational vaccine-induced neutralizing antibodies in mice when given as two intramuscular injections of a 1-microgram (mcg) dose three weeks apart.
Additional experiments found that mice were given two injections of the 1-mcg dose and later challenged with SARS-CoV-2 virus either five or 13 weeks after the second injection was protected from viral replication in the lungs and nose.
Importantly, mice challenged seven weeks after only a single dose of 1 mcg or 10 mcg of mRNA-1273 were also protected against viral replication in the lungs.
According to the researchers, the investigational vaccine also induced robust CD8 T-cell responses in the mice.
It did not induce the type of cellular immune response that has been linked to vaccine-associated enhanced respiratory disease (VAERD), they said.
This rare, allergic-type inflammation was seen in individuals vaccinated with a whole-inactivated respiratory syncytial virus (RSV) vaccine in the 1960s.