An Overview of the Novavax COVID-19 Vaccine

Novavax is a Maryland-based biotech company that has taken a traditional approach to developing a vaccine against COVID-19.

The company began a Phase 3 trial of its vaccine candidate, NVX-CoV2373, in the United Kingdom in September 2020. This was followed by a second Phase 3 trial in the United States and Mexico in December 2020. These two late-stage trials enrolled a total of almost 50,000 people.

This put Novavax behind its competitors, but early results showed promise. The company announced the vaccine was 90% effective overall in the PREVENT-19 Phase 3 trial. And it was 100% effective against moderate and severe disease.

On August 19, 2022, the Food and Drug Administration (FDA) authorized the Novavax COVID-19 Vaccine, Adjuvanted for emergency use in individuals ages 12 and older. It is the first protein-based COVID-19 vaccine authorized in the U.S.

How It Works

The Novavax vaccine uses a custom-made spike protein that mimics the natural spike protein in the SARS-CoV-2 virus. Novavax has for years worked on developing its recombinant nanoparticle technology, and created the first COVID-19 vaccine using this method in the spring of 2020.

By summer 2020, early clinical trials showed that the vaccine appeared to be safe, and more advanced trials entered the planning stage in the United States and other countries.

The two-dose vaccine works by introducing a protein that prompts an antibody response, which blocks the ability of future coronavirus to bind to human cells and prevents infection. The protein is combined with Novavax’s Matrix-M adjuvant, which is important in enhancing the immune response elicited by the protein antigen.

How Effective Is It?

Early vaccine trial results published by Novavax revealed a strong antibody response to the vaccine in animals. By August 2020, early human trials showed strong antibody responses with no serious adverse events and few side effects.

Novavax announced on June 14, 2021, that the vaccine was 90.4% effective in a preliminary analysis of data from its Phase 3 trial in the U.S. and Mexico. It was also 100% effective against moderate and severe disease. The trial was conducted when the Alpha variant B.1.1.7 was the predominant strain in the U.S.

The company also announced that the vaccine was 60% effective in a Phase 2b clinical trial in South Africa and included protection from the Beta variant B.1.351. A later study comparing three doses of the Novavax vaccine and three doses of an mRNA vaccine found that they produced similar immune responses against the Omicron variants BA.1 and BA.4/BA.5.

In Novavax's trial, participants were not directly exposed to the virus, but instead researchers used a natural infection approach. This method was also used for the three COVID-19 vaccines that received approval or emergency use authorization (EUA) from the FDA.

When Will It Be Available?

Novavax's vaccine candidate generated a lot of interest because early animal study data showed that it was highly effective at preventing replication of the coronavirus in nasal passages. It was an important development for COVID vaccines since it suggested that it may help reduce both infection and transmission rates.

Novavax's vaccine also relies on an established delivery method and can be stored at standard refrigerator temperatures. The available mRNA vaccines have to be frozen for longer-term storage, so the Novavax vaccine may be a better option in settings with limited freezer capacity.

However, Novavax was behind its competitors when it came to clinical trials. Now that Novavax has received emergency use authorization from the FDA, it is now available and is being given to people in the U.S.

The U.S. secured 3.2 million doses of Novavax’s COVID-19 vaccine in July 2022, and later ordered an additional 1.5 million doses in February 2023.

Throughout the development of their vaccine, Novavax has faced challenges and experienced significant delays due to manufacturing issues. Science magazine reported that the company had sold some of its manufacturing facilities and had to rely on more contractors to manufacture many of its vaccines. There were also delays in receiving authorization, as the FDA needed to review changes made to Novavax's manufacturing process.

In December 2021, Novavax began development of a vaccine targeting the Omicron variant. They began a Phase 3 clinical trial in May 2022 to study their vaccine candidates targeting the BA.1 and BA.5 Omicron subvariants. This trial is expected to complete in July 2023.

Who Can Get the Novavax Vaccine?

The Novavax COVID-19 vaccine is available for everyone 12 years and older. It is given as a two-dose primary series, three to eight weeks apart.

The Novavax vaccine is also authorized as a first booster dose, but only for people who cannot or choose not to receive an mRNA vaccine. This dose is given at least 6 months after completing a primary series of any vaccine. 

Novavax had announced on June 14, 2021, that it completed enrollment of 2,248 adolescents in its Phase 3 trial in adolescents ages 12 to 17. In February 2022, the company reported that the vaccine demonstrated 82% clinical efficacy against the Delta variant and planned to seek FDA authorization for this age group. Then on August 19, 2022, the FDA authorized the Novavax vaccine for individuals ages 12 years and older. Novavax also expects to initiate additional studies in younger children.

Side Effects and Adverse Events

Adults who took part in Novavax's Phase 3 trials were asked to record any local or systemic reactions after each dose of the vaccine.

The most commonly reported side effects were:

• Injection site pain, swelling, and redness
• Fatigue
• Muscle pain
• Headache
• Joint pain
• Nausea/vomiting
• Fever
• Chills

Injection site pain lasted less than three days and fatigue, headaches, or muscle pain lasted less than two days in the Phase 3 trials.

Although rare, hypersensitivity reactions, lymphadenopathy-related reactions, myocarditis, and pericarditis were also reported in some people who received the Novavax vaccine.

Funding and Development

Novavax has been awarded more than $2 billion globally for its efforts to develop a COVID-19 vaccine, with $1.6 billion from the U.S. government alone. The U.S. funds were given as a part of Operation Warp Speed and from the Biomedical Advanced Research and Development Authority (BARDA). BARDA is a program of the Department of Health and Human Services. This program and Operation Warp Speed sought to speed up how quickly vaccines to fight COVID-19 can be developed and approved for use.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.