New Vaccine Trial: Is it a Game Changer?

Last updated May 29th 2020, 7:19:53pm

It’s hard to miss the Moderna vaccine trial news. On May 18, when it was announced, the stock market climbed almost 4%. It’s not hard to see why: a vaccine for COVID-19 would be a complete game changer. It’s not the only way out of this, but it’s certainly the most straightforward.

But let’s dig into the news: is it really a game-changer?

We can start by putting this in context. There are an extremely large number of COVID-19 vaccines under development; we have a full review in our Vaccine Explainer here. All vaccines work in roughly the same way -- they induce your body to develop antibodies to the virus, so when you encounter it in the wild, you are ready.

The two more traditional ways to do this -- used in most of the vaccines we have -- involve either (a) introducing a weakened or killed form of the virus to your body which induces a response without making you sick or (b) introducing the viral antigen directly to your body, which prompts antibody formation. In option (b), the key is that the antigen part of the virus alone doesn’t make you sick.

These are both tried and true methods for vaccine development, but they are also fairly slow. There are a lot of safety hurdles with the weakened vaccine method, and the direct antigen method requires manufacturing antigens.

There are also newer approaches which aim to induce your body to produce antigens directly, by introducing the viral DNA into your cells. This is hard to do (your cells do not want to let stuff in, for good reason), but there are approaches which rely on using genetically modified viruses to introduce the DNA, or those which rely on non-viral delivery of the DNA.

This last group - called nucleic acid vaccines - are the newest and most untested. There are no vaccines in use which have been developed using this method. However: they have enormous promise. They have the potential to be manufactured very fast and have more limited safety issues than killed or weakened virus vaccines.

The Moderna vaccine is in this group. It uses an “mRNA” delivery approach to bring SARS-CoV-2 viral DNA into cells, in the hopes they will manufacture viral antigens. Then, the idea is that the body will respond by making antibodies.

The big news is results from the Phase I trial of the vaccine. Phase I is the very first of, typically, 3 phases of viral development. It is an initial, typically very small, test of efficacy and safety and dosage. In this particular test, healthy, young volunteers were carefully selected and given the vaccine. They were monitored for development of antibodies to the SARS-CoV-2 virus. If they developed antibodies, then these antibodies were tested against virus infected cells in the lab to see if they stopped viral growth.

The trial has been successful, at least so far. The company produced data from the first 8 patients in the trial (they are processing more patients now). In these 8 patiens, the drug induced antibody formation. And, when the antibodies were taken out from their body, they were able to successfully inhibit virus in the lab.

The results so far also showed that the vaccinated people produced similar antibody levels to what has been observed with patients recovering from COVID-19, with patients in the higher dose group actually producing antibodies at a significantly higher level than seen in COVID19 survivors. There were limited side effects (including redness at the injection site, slight fevers) and they appeared only at the highest doses of the drug; the company is therefore focusing on lower doses going forward, which seem to have similar efficacy and are more efficient (you can treat more people with the same amount of vaccine).

There are more people enrolled in this particular Phase I trial, so we are likely to see more results from this over the next few weeks. Meanwhile, Moderna has moved onto the next phase.

This is all really good, promising news. It’s exciting! We are excited.

There is, however, a long way to go.

  • Phase II trials: Larger samples, with the intention of showing actual protection against the virus in the world. The evidence so far shows that the antibodies people produce can kill virus in the lab. This isn’t the same as preventing infection. It is related, and what we have seen is a really good sign. But we need to see performance in the world.
  • Phase III trials: Large-scale randomized trials to show efficacy in a wide range of populations.
  • Manufacturing. Even once we have a vaccine, we need to make lots of it. Then we need people to get it. This is a massive logistical undertaking.

In normal times, getting through these steps would take years. Everything in COVID-19, though, is very very very sped up. But there is still a long way to go. Still, progress is progress.