How the Novavax Covid-19 Vaccine Works

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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 expects to release 100 million doses for use in the United States by 2021.


Sources: National Center for Information on Biotechnology; Nature Reviews Immunology; Science; Maria Elena Bottazzi, Baylor College of Medicine.

Tracking the coronavirus

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