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expert reaction to Moderna announcement about their phase 1 trial data on their mRNA vaccine (mRNA-1273) candidate against COVID-19

There have been journalists questions abou the anouncment made by Moderna about their phase 1 trial data on their mRNA vaccine (mRNA-1273) candidate against COVID-19.


Prof Robin Shattock, Professor of Mucosal Infection and Immunity, Imperial College London, said:

“These are encouraging signs – while it will be important to scrutinise the actual data, the reported findings are in line with expectations that vaccine candidates should provide levels of neutralising antibodies that are at least equivalent to convalescent subjects.  This is a promising start, but efficacy data will be key followed by an ability to scale in a manner that provides global access should this vaccine be successful.”


Prof Stephen Evans, Professor of Pharmacoepidemiology, London School of Hygiene & Tropical Medicine, said:

Is this good news?

“Well it isn’t bad news and there are a number of good points that suggest optimism that this vaccine may work.  It is early results from a trial in which three doses (25, 100 and 250 micrograms-mcg) were given to each of three age groups.  These results refer to the youngest of the groups and the data are not complete for all dose groups.

Do the results look convincing?

“It is very difficult to be sure of the results from a press release.  It must be noted that this is a Phase 1 study which has an object of showing the vaccine is able to induce an antibody response and that the dose range is appropriate.  It would seem that the phase 2 trial which will follow this phase 1 trial will use two doses 50 and 100mcg with a view to selecting an optimum dose to use in a Phase 3 trial planned to begin in July.  It will not be until the Phase 3 trial is completed that it will be known whether the vaccine actually prevents Covid-19 disease.  This trial measures what is called “immunogenicity” which is the antibody response that is a minimal requirement for the vaccine to work.  It also assesses “reactogenicity” which is studying whether there are immediate reactions to the vaccine like skin rashes.  These are common with almost all vaccines and this vaccine produces them, but not at a rate to cause serious concern.  The trial also checks for the overall absence of significant harms (safety), but given the small numbers this is only a preliminary assessment.

Any caveats or limitations?

“As noted above, the trial is not intended to show efficacy in reducing or preventing Covid-19 disease and it cannot be assumed on the basis of these results that it will do so.  The phase 3 trials will assess this, so it is important not to overstate these results.  Whether the same benefits are seen in older age groups we do not know but that may be because they were recruited at a later stage.”


All our previous output on this subject can be seen at this weblink:


Declared interests

Prof Robin Shattock: “Working on a self-amplifying RNA COVID-19 vaccine, developed by Imperial College and funded by the UK government through different agencies including DHSC and NIHR.”

Prof Stephen Evans: “I am the statistician to the “meta-Data Safety and Monitoring Board” for CEPI [].  I will probably be paid for my attendance at meetings and expenses for travel.  CEPI have provided funding to the Oxford vaccine work.  I am funded (1 day/week) by LSHTM.  They get funding from various companies, including Astra Zeneca and GSK but I am not funded by them, I have no involvement in obtaining funding from them and I am not an investigator or any grants obtained from them.”

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