Covid-19 vaccine shows early promise

Signs of promise for a Covid-19 candidate vaccine have been reported by biotechnology company Moderna.

The company announced positive interim clinical data for its mRNA-1273 candidate vaccine against Covid-19 on Monday (18 May).

Data from the Phase 1 study led by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), show that neutralising antibodies were found in eight participants of the trial. The data, however is admittedly small, with the trial including a total of 45 patients across three arms of the study. 

Specifically, the trial shows that eight patients taking the vaccine at low-middle dosses, developed neutralising antibodies in similar levels to patients who had recovered from Covid-19.

“At this time, neutralising antibody data are available only for the first four participants in each of the 25 µg and 100 µg dose level cohorts. Consistent with the binding antibody data, mRNA-1273 vaccination elicited neutralising antibodies in all eight of these participants, as measured by plaque reduction neutralisation (PRNT) assays against live SARS-CoV-2. The levels of neutralising antibodies at day 43 were at or above levels generally seen in convalescent sera,” the company said in a statement.

The study also showed that Moderna’s mRNA-1273 vaccine had a safety profile that was similar to other vaccine clinical studies conducted by the company. The most notable safety event from the study comes from three patients being given a higher dose of the candidate vaccine (250 µg), who then went on to develop grade three systemic symptoms, following a second dose. Grade three events are classed as serious and can require medical intervention. No serious events requiring hospital interventions have been reported.

Moderna is now basing its Phase 2 study of the candidate vaccine to study two dose levels of 50 µg and 100 µg, and will amend its Phase 1 study to include a 50 µg dose across three age groups. The company has stated it expects to start Phase 3 of the trial in July and is also scaling up its manufacturing capacity for the vaccine.

The candidate vaccine was also been tested in mice, preventing viral replication of Covid-19 in the lungs of the animals, the company stated.

“These interim Phase 1 data, while early, demonstrate that vaccination with mRNA-1273 elicits an immune response of the magnitude caused by natural infection starting with a dose as low as 25 µg,” said Tal Zaks, chief medical officer at Moderna. “When combined with the success in preventing viral replication in the lungs of a pre-clinical challenge model at a dose that elicited similar levels of neutralising antibodies, these data substantiate our belief that mRNA-1273 has the potential to prevent Covid-19 disease and advance our ability to select a dose for pivotal trials.”

“With today’s positive interim Phase 1 data and the positive data in the mouse challenge model, the Moderna team continues to focus on moving as fast as safely possible to start our pivotal Phase 3 study in July and, if successful, file a BLA,” said Stéphane Bancel, chief executive pfficer at Moderna. “We are investing to scale up manufacturing so we can maximise the number of doses we can produce to help protect as many people as we can from SARS-CoV-2.”