HomeScienceWe have another highly effective COVID vaccine, based on different tech

We have another highly effective COVID vaccine, based on different tech

Image of a man receiving an injection.
Enlarge / A participant gets his second dose of the Novavax vaccine during the clinical trial.

Today, a company called Novavax announced that it had completed a large efficacy trial of its COVID-19 vaccine, and the news was good. The vaccine is highly effective, it blocked severe disease entirely, and it appeared to work against some of the more recently evolved virus variants. The company says it can produce 150 million doses per month by the end of the year, and the vaccine is stable when stored in a normal freezer, so it could play a big part in the effort to administer vaccines outside of industrialized nations.

Different tech

So far, US citizens have had the choice of RNA-based vaccines, like the offerings from Moderna and Pfizer/BioNTech, or a vaccine based on a harmless virus engineered to carry the coronavirus spike protein, as used in the Johnson & Johnson vaccine. (The AstraZeneca and Sputnik vaccines are similar to J&J’s.) Outside the US, many countries have used vaccines based on an inactivated coronavirus, although these have turned out not to be very effective.

The Novavax vaccine uses an entirely different technology. Vaccine production starts by identifying a key gene from the pathogen of interest—the SARS-CoV-2 spike protein, in this case—and inserting it into a virus that infects plant cells. Plant cells can easily be grown in culture, and they process any proteins they make in the same way that human cells do. (This processing can involve chemically linking sugars or cleaving off superfluous parts of the protein.) The activity ensures that the purified protein will be chemically identical to the spike protein found on the surface of the SARS-CoV-2 virus itself.

The company’s description of the vaccine development from here on out is a bit vague, but it appears that the vaccine builds a large complex of proteins that includes multiple copies of the spike protein. So rather than being made up of individual dispersed copies of the spike protein, the vaccine consists of a smaller number of large complexes that have multiple copies of the spike. These complexes can be described as nanoparticles and are similar in scale to an actual virus, hypothetically enhancing the immune system’s response.

In addition, the company mixes in a molecule called an “adjuvant.” This chemical is unrelated to the protein that creates the immune response, but it seems to heighten the response regardless. In this case, the adjuvant is a sugar-containing molecule isolated from plants; it’s a relative of an adjuvant that is already used as a food additive (it helps give root beer a foamy head when poured).

Like some other vaccines, Novavax’s offering, NVX-CoV2373, is administered in two doses separated by a few weeks. Unlike the RNA vaccines, it can be stored in regular freezers, allowing it to be used in locations with no robust public health infrastructure. And because it relies on a very different technology, it shouldn’t be in direct competition with other vaccines for most of its raw ingredients.

Promising results

The numbers released by Novavax today look very similar to the efficacy of other two-dose vaccines. The company’s clinical trial enrolled nearly 30,000 people in the US and Mexico, with twice as many participating in the experimental group as in the control. There were 77 confirmed SARS-CoV-2 infections, with 63 of those occurring in the placebo group, which translates to a 90 percent efficacy.

All 14 cases in the vaccine group were mild, while the placebo group saw 10 moderate and four severe cases. The vaccine blocked all severe infections, although some will undoubtedly occur when the vaccine is in broader use.

The trial included the period when the Alpha variant (formerly B.1.1.7) became the predominant form of the virus in the US. While the analysis involved a smaller number of cases, it appears that NVX-CoV2373 is also highly effective against this and other variants.

Side effects were generally similar to other vaccines, with headaches, fatigue, and pain at the injection site being common.

This all suggests that Novavax will have little trouble gaining an Emergency Use Authorization when it applies for one from the Food and Drug Administration. The company indicates it will do so in the next quarter, at which point it will be able to manufacture 100 million doses a month. That number is expected to rise to 150 million per month before the year is out.

The US currently has an excess of vaccine supply and has started to send doses to other countries, in some cases directly and in others via an international program set up to increase global vaccination levels. As such, the availability of an additional vaccine is unlikely to change the dynamics of vaccinations in the US. But the availability of the volumes promised by Novavax could make a massive difference to international efforts, especially given the ability of NVX-CoV2373 to be shipped in standard freezers.

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