How the Novavax Covid-19 Vaccine Works
Maryland-based company Novavax has developed a protein-based coronavirus vaccine called NVX-CoV2373. The vaccine produced remarkably high levels of antibodies in early clinical trials. The vaccine entered a Phase 3 clinical trial in the UK in September and another in the US in late December. These studies will show whether the vaccine is safe and effective.
Coronavirus proteins
The SARS-CoV-2 virus is loaded with proteins that it uses to enter human cells. These so-called spike proteins are a tempting target for potential vaccines and treatments.
The Novavax vaccine teaches the immune system to make antibodies against the spike protein.
Growing spike proteins
To make their vaccine, the Novavax researchers started with a modified spike gene. They inserted the gene into another virus called a baculovirus and made it infect insect cells. The infected cells produced spike proteins, which spontaneously joined together to form spikes, as is the case on the surface of the coronavirus.
Three spines
Proteins combine
Three spines
Proteins combine
Three spines
Proteins combine
Three spines
Proteins combine
Three spines
Proteins combine
Three spines
Proteins combine
A similar method of growing and harvesting viral proteins is already being used to make approved vaccines against diseases such as influenza and HPV.
Build nanoparticles
The researchers harvested the spike proteins from the insect cells and assembled them into nanoparticles. While the nanoparticles mimicked the molecular structure of the coronavirus, they failed to replicate or cause Covid-19.
Nanoparticles
occupied with
spikes
Nanoparticles
occupied with
spikes
Nanoparticles
occupied with
spikes
Presentation of the tip
The vaccine is injected into the muscles of the arm. Each injection contains many spike nanoparticles as well as a compound extracted from the soap bark tree. The compound attracts immune cells to the injection site and causes them to respond more strongly to the nanoparticles.
Immunity primer
connection
Immunity primer
connection
Discover the intruder
Immune cells, so-called antigen-presenting cells, hit the vaccine nanoparticles and ingest them.
Present
Spike protein
Fragments
Present
Spike protein
Fragments
Present
Spike protein
Fragments
An antigen presenting cell ruptures the spike proteins and shows some of their fragments on its surface. A so-called helper T cell can detect the fragments. When a fragment fits into one of its surface proteins, the T cell is activated. Now it can recruit other immune cells to respond to the vaccine.
Make antibodies
Another type of immune cell called a B cell can also encounter the vaccine nanoparticles. B cells have surface proteins in a variety of shapes, and some may be the correct shape to attach to a spike protein. When a B-cell becomes stuck, it can pull in the vaccine particle and present spike protein fragments on its surface.
When a helper T cell activated against the spike protein binds to one of these fragments, it activates the B cell. Now the B cell is multiplying and releasing antibodies that have the same shape as their surface proteins.
Matching
Surface proteins
Matching
Surface proteins
Matching
Surface proteins
Matching
Surface proteins
Matching
Surface proteins
Matching
Surface proteins
Matching
surface
Proteins
Matching
surface
Proteins
Matching
surface
Proteins
Matching
Surface proteins
Matching
Surface proteins
Matching
Surface proteins
Stop the coronavirus
When vaccinated people are later exposed to the coronavirus, their antibodies can bind to the spike proteins. The coronavirus cannot enter cells and the infection is blocked.
Kill infected cells
The Novavax vaccine can also provide another type of protection by destroying infected cells. When a coronavirus enters, infected cells place fragments of its spike protein on their surface. Antigen presenting cells can activate a type of immune cell called a killer T cell. It can detect and destroy cells infected with coronaviruses before they can produce new viruses.
Present a
Spike protein
fragment
Beginning
to kill them
infected cell
Present a
Spike protein
fragment
Beginning
to kill them
infected cell
Present a
Spike protein
fragment
Beginning
to kill them
infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Present a
Spike protein
fragment
I'm starting to kill
the infected cell
Memory of the virus
Novavax's vaccine would be easier to distribute and store than Pfizer-BioNTech and Moderna's vaccines. While these vaccines must be kept frozen, NVX-CoV2373 can be stable in the refrigerator for up to three months. However, should the vaccine prove effective, scientists will not know exactly how long it will protect.
Second dose
21 days later
Second dose
21 days later
Second dose
21 days later
When it works like protein-based vaccines against other diseases, it can make a group of special cells called memory B cells and memory T cells. These cells store information about the coronavirus for years or even decades, enabling a quick counterattack in response to a new infection.
Vaccination schedule
January 2020 Novavax begins work on a coronavirus vaccine.
A screen showing protein structures in a Novavax laboratory in Maryland.Andrew Caballero-Reynolds / Agence France-Presse
Can Novavax starts clinical trials for its vaccine.
July The US government is giving Novavax $ 1.6 billion to support clinical trials and manufacturing of the vaccine.
August Novavax started a phase 2 study with 2,900 people in South Africa.
Preparing an injection in Johannesburg, South Africa.Joao Silva / The New York Times
September Novavax is starting a phase 3 study with up to 15,000 volunteers in the UK. The study is expected to deliver results in early 2021.
December 28th Novavax is starting a phase 3 study with 30,000 people in the United States. The trial had been delayed due to problems making the doses required for the study.
2021 If the clinical trials are successful, Novavax is expected to ship 100 million doses for use in the United States in 2021.
Sources: National Center for Information on Biotechnology; Nature Reviews Immunology; Science; Maria Elena Bottazzi, Baylor College of Medicine.
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