Moderna’s coronavirus vaccine hits first objectives

The first data is in from Moderna’s mRNA-based coronavirus vaccine, and it’s good news – the shot stimulated COVID-19 antibodies in healthy volunteers.

There’s still a long way to go before it can be said that the mRNA-1273 vaccine is effective, but the results mean that the phase 1 trial has achieved its objectives, allowing Moderna to move ahead with a phase 3 programme that it now expects to start in July.

The results are the first human data in the global effort to develop a vaccine against SARS-CoV-2, the virus that causes COVID-19 and has now killed more than 315,000 people worldwide. There are at least eight vaccines already in trials, and more than 100 others in preclinical development around the world.

mRNA-1273 also provided full protection against viral replication in the lungs in a preclinical mouse challenge model, according to Cambridge, Massachusetts-based Moderna.

Shares in the US biotech spiked around 23% after the data emerged from the study, which was led by scientists at the US National Institute of Allergy and Infectious Diseases (NIAID).

The first readout of data comes after two injections of the two lower doses of the vaccine – 25mcg and 100mcg – and one injection of the higher 250mcg arm in the ongoing study.

There were 15 patients in each dose group, and all had an antibody response to the vaccine by day 15 after a single dose. Even at the lowest dose, two weeks after vaccination antibody levels were at the same sort of level as is seen in people who have recovered from COVID-19.

The key finding however was in a group of eight patients who had been tested for the presence of neutralising antibodies – in other words they could bind to and inactivate the virus in the lab.

All eight – four apiece in the 25 mcg and 100mcg dose groups – were found to have neutralising antibodies to COVID-19. Moderna reckons it now has enough evidence to support taking both those doses forward into phase 3.

If the July timeline is met, the move from discovery to phase 3 trials will have taken just a few months, which is lightning speed for a vaccine programme and raises the hope that a candidate could be available for use next year.

Moderna also said its vaccine was well-tolerated by the volunteers, although there were some cases of grade 3 (moderate) toxicity in the 250mcg group. It is removing that dose from the studies, and adding a 50mcg group to its phase 1 trial.

“This interim phase 1 data, while early, demonstrates that vaccination with mRNA-1273 elicits an immune response of the magnitude caused by natural infection, starting with a dose as low as 25mcg,” said Tal Zaks, Moderna’s chief medical officer.

“When combined with the success in preventing viral replication in the lungs of a preclinical challenge model at a dose that elicited similar levels of neutralising antibodies, this data substantiates our belief that mRNA-1273 has the potential to prevent COVID-19 disease,” he added.

mRNA vaccines harness the body’s cellular machinery to make viral proteins that then act as antigens, stimulating an immune response. So far, no vaccines based on mRNA have been approved anywhere in the world, although there are plenty in clinical development.

The mRNA-1273 vaccine stimulates the body to make antibodies against a stabilised form of the spike (S) protein found on SARS-CoV-2, which is used by the virus to anchor onto host cells.

Other groups developing mRNA vaccines for the SARS-CoV-2 include Pfizer/BioNTech, which started their trial in Germany in April and the US earlier in May, and Imperial College London in the UK which is due to start trials of its candidate in June.