It's possible that existing vaccines won't be as effective if the Omicron variant is different from the original variant. It's likely that companies will need to update their vaccines if that's the case.
Deborah is a microbiologist who has been studying vaccines for over two decades. She explains how vaccines might need to be updated.
1. Why should vaccines be updated?
It's a question of whether the original vaccine's ability to recognize and fight the new variant of the virus has been compromised.
The spike proteins that coronaviruses use to attach to the ACE-2 receptors on the surface of human cells can be seen in the picture. The instructions in the form of mRNA that direct cells to make a harmless version of the spike is what all the COVID-19 vaccines work on.
The human body is then stimulated to produce antibodies. If a person is exposed to the coronaviruses, these antibodies bind to the coronaviruses's spike protein and interfere with its ability to cause disease.
The Omicron variant has a new pattern of mutations. The changes could affect the ability of the current vaccines to bind to the spike protein. The vaccines could be less effective if that happens.
Moderna and Pfizer have existing vaccines that have a spikeProtein from the original strain of coronaviruses. In a new vaccine, the instructions for the Omicron spike would be written in the mRNA.
A new vaccine would be more effective at binding the Omicron virus and preventing it from infecting cells if the genetic code of the original spike was swapped for the new variant.
People who have already been exposed to the new strain of COVID-19 would need only a single booster dose of a new vaccine to be protected from other strains.
If Omicron emerges as the dominant strain over Delta, those who are unvaccinated would only need to receive a few more doses of the updated vaccine. If Delta and Omicron are both in circulation, people would likely get a combination of the current and updated vaccines.
Changing the sequence of the mRNA will make it match the new variant. The images are courtesy of iStock.
3. Scientists update a vaccine.
To make an updated vaccine, you need two ingredients: the genetic sequence of the spike protein from a new variant of concern and a DNA template that would be used to build the vaccine.
Most organisms have the instructions for making mRNA in their genes. Since the genetic code for the Omicron spike is already published, researchers can now make a template for the spike that will be used to make the new vaccines.
The researchers mix the DNA templates with the synthetic enzymes and the building blocks to make the messenger RNA. A process called transcription is the process of building an mRNA copy of a DNA template.
This process can be used to produce a batches of the vaccine messenger RNA. The instructions are protected until they are safely delivered into cells in your arm.
4. How long before a new vaccine is ready?
It takes three days to create the template for the vaccine. It would take about a week to make enough vaccine for testing in the lab and another six weeks to make enough for pre-clinical tests on human cells.
Within 52 days, scientists could have an updated vaccine ready to plug into the manufacturing process and begin producing doses for a human clinical trial. It would take at least another few weeks to update and test a new vaccine.
While that trial is going on, manufacturers could change their process to make a new vaccine. If the vaccine gets approved, a company could immediately start rolling out the new vaccine.
It's not clear how much clinical data would be required to get FDA approval for an updated COVID-19 vaccine. A new vaccine would have the same ingredients.
The only difference would be a few lines of genetic code. An updated vaccine is basically the same as the already tested vaccines. Clinical testing may not need to be as extensive because of the similarities.
Clinical trials for an updated vaccine would likely need to be done with safety testing and confirmation that the vaccine is equivalent to the original vaccine against the original strains. If these are the only requirements, researchers would only enroll hundreds of people to get the clinical data they need.
It is important to note that if vaccine manufacturers decide to update their vaccines for the Omicron variant, it wouldn't be the first time.
In October 2020 there was a previous variant, B.1.351, that was resistant to the current vaccines. The potential threat was responded to quickly by the creation of an updated vaccine and the testing of the new vaccine.
The variant did not become the dominant variant. If it had, vaccine manufacturers would have been ready to make an updated vaccine.
Companies are ready to meet the challenge if it turns out that Omicron warrants a new vaccine.
The University of Washington has a Professor of Microbiology.
The Conversation's article is a Creative Commons licensed one. The original article can be found here.
