Today, news broke that one of about a dozen vaccine candidates for COVID-19 passed Phase I trials in human beings. And the results, according to the vaccine manufacturer Moderna, were rather optimistic. As with any such announcements, we should probably remain cautious and not overstate any potential news. But it is somewhat good news nonetheless.

Messenger RNA Vaccine

The new vaccine candidate, produced by Moderna in partnership with the National Institutes of Health, is a messenger RNA vaccine. In Phase I trials starting earlier this year, the vaccine was tested on 45 people. This first set of test participants for Moderna’s trial COVID-19 vaccine was broken into three groups. Each group received a different dose of the vaccine. All groups received both an initial shot and a booster shot a month later.

A new messenger RNA vaccine produced by Moderna is entering Phase II trials for COVID-19. Messenger RNA provides a new approach to vaccination — signalling the immune system directly to produce specific antibodies. Such vaccines show promise for dealing with typically difficult to vaccinate illnesses such as flu and some forms of cancer. Image source: PHG.

Moderna is producing and testing a messenger RNA vaccine to target the virus for SARS-CoV-2 in a new approach. A particular immunization process that provides a kind of RNA that tells immune cells what specific kinds of antibodies to build. Such messenger RNA vaccines have advantages in that they are often faster and cheaper to produce than other kinds of vaccines and can directly communicate to the immune system a given infection-fighting need. Messenger RNA vaccination has shown promise in tackling some of the most difficult to vaccinate illnesses such as flu and even some forms of cancer.

Good Results in Phase I Trial — Moving to Phase II

In Moderna’s Phase I COVID-19 trial, results included expressed coronavirus antibodies in all test participants, the presence of neutralizing antibodies in laboratory cell tests, and only minor side effects. All test participants showed immunogenicity — the ability to produce antibodies capable of fighting COVID-19. This is a key step in vaccine viability. Further, 8 test subjects were more closely examined in a laboratory environment. Each of these subjects were found to possess antibodies capable of preventing COVID-19 infection. These neutralizing antibodies bind to the virus, disabling its ability to attack human cells. Finally, the company reported that the vaccine produced no serious side effects. Minor side effects included — redness at the injection site, headache, fever and flu-like symptoms. None lasted for more than a day.

Though Moderna’s vaccine produced promising results in the laboratory, it is not yet known if the vaccine is capable of producing immunity in real world environments. To this end, the FDA has granted Moderna approval to move on to Phase II trials. Moderna plans to test an additional 600 participants during Phase II — of which about 300 are older than 55 — to help determine the vaccine’s practical viability. In Phase II trials, vaccine developers typically test thousands. But given the fact that COVID-19 is so lethal — killing thousands of people each day worldwide — Moderna’s Phase II trial is being accelerated based on critical need for a life-saving vaccine.

It is expected that Phase III trials will begin in July if the vaccine continues to show viability following Phase II. Phase III is the final phase before a vaccine is approved for general public use. Phase III typically involves many thousands of participants.

Some Questions Raised About Moderna’s Announcement

Though Moderna’s announcement may provide a greatly desired spark of hope for an eventual, if somewhat longer term, resolution to the present pandemic, questions about the announcement have been raised by some in the medical reporting community. STAT — an American health oriented news site run by John W. Henry who owns the Boston Globe — recently reported some of these concerns. Primarily, so far, it appears that Moderna has, as yet, not provided enough data for a full peer review of its vaccine by the public community of experts. STAT also raised the question of whether the other 37 participants in the study produced binding antibodies (Moderna has not yet clarified this point — only stating that 8 participants showed binding antibodies). Another issue is time-frame for vaccine durability. STAT notes that study participants produced antibodies two weeks after vaccination. So, as yet, we have no information regarding the issue of how long Moderna’s vaccine results in a protective antibody response. All the issues raised by STAT are worth considering and provide good reason to remain cautious about early COVID-19 vaccine announcements.

Public Availability Still Many Months Away

Regardless of whether or not Moderna’s particular vaccine candidate proves valid, the time-frame for the public availability of any vaccine, even in the best case, would be the end of 2020. Dr. Anthony Fauci stated that it would take 12-18 months to develop a vaccine and have it widely available on the market in the best case scenario. Moderna representatives have estimates that follow similar timelines — stating that market availability is likely to take until January through June of 2021.

And this is if things go well. If both Phase II and Phase III trials are a success and the laboratory demonstrated viability that Moderna claims is validated in a real-world environment.

If things do go well, it’s possible that Phase III trials could be conducted in a manner that targets highest risk populations so as to have some impact on preventing infection and reducing loss of life due to COVID-19. There is historical precedent for limited vaccine use in this manner — as occurred during the 1957 H2N2 flu pandemic. At that time limited vaccine doses were targeted for greatest effect during late 1957. But this could only happen in the presence of effective testing to determine hot spot regions and communities. So the broader Phase III trials could start to target those populations in a meaningful way if such a practice were determined to be safe, humane, and effective by health experts.

Nevertheless, such a capability is still months away in the best case and a broader publicly available vaccine is unlikely before year end at the earliest. So let’s not get too far ahead of ourselves. That said, it is nice to be able to share a bit of qualified good news in this difficult time.

(UPDATED to include new information from STAT and to further apply journalistic standards.)