At the beginning of the COVID-19 pandemic, countries around the world found themselves in a race against time. Measures like travel and border restrictions, stay-at-home orders, and business closures were enacted to slow down the spread of the virus. Stringent measures such as social distancing and requiring citizens to wear masks added another layer of precaution to the global quarantine.
Today, scientists lead the world towards another goal: the race towards finding a COVID-19 vaccine. There are now 100+ coronavirus vaccine efforts according to the World Health Organization (WHO). Which ones show the most potential? What kind of timeline are we looking at?
Learn more about the top 5 most promising vaccine candidates in the global push to flatten the curve.
Adenovirus Vaccine
How it Works:
Adenoviruses cause mild infections like the common cold and exist in the wild in humans. These viruses are being genetically engineered to produce viral antigens that have been found in SARS-CoV-2, specifically the infamous spiked protein that the COVID-19 virus uses to enter human cells.
When put into a vaccine, these genetically-engineered adenoviruses will protect the human body against COVID-19 by triggering an immune response.
Should it be successful, the adenovirus vector vaccine will be the first of its kind. No such vaccine for other diseases has been created, even though scientists have also started to conduct clinical trials using this platform for Ebola, influenza, HIV, and malaria.
Potential Drawbacks:
Live viruses, those found in vaccines carry a risk for immunocompromised individuals.
RNA Vaccine
How it Works:
Traditional vaccines work by placing antigens derived from the virus or inactivated versions of the virus, into the body. On the other hand, RNA vaccines involve injecting mRNA into cells themselves. Instead of introducing the virus from the outside, RNA vaccines directly produce the viral proteins inside the human body.
The “m” in mRNA means “messenger,” which is an apt term for its basic function – the molecule mRNA takes instructions from DNA to the ribosomes, aka the protein factories of the cell. These will then produce the required viral proteins against diseases like COVID-19.
A major advantage of mRNA vaccines is that scientists no longer have to produce viral proteins in the laboratory. Instead, the body itself will produce the protein after receiving the molecular instructions from the mRNA.
In the case of COVID-19, scientists will take the RNA sequence from the virus genome of SARS-CoV-2. Injected into the body, it will then stimulate an immune response designed to stop the disease. Other advantages of this platform is the faster production process and cheaper costs, which gives them the massive potential to be scalable and easier to distribute during a worldwide pandemic.
Potential Drawbacks:
mRNA vaccines have never been used before, so there’s a huge risk of failure. Biotech startup Moderna has also observed Grade 3 reactions such as high fever, nausea, and pain among its trial volunteers. These factors may decrease the general enthusiasm for an RNA vaccine.
Inactivated Pathogens
How it Works:
Inactivating a virus, then injecting someone with it, is one of the most traditional approaches to creating a vaccine. The virus is weakened sufficiently or killed before the injection so that it doesn’t cause any serious infections. Once injected into the body, the presence of the inactivated virus triggers the human immune system to produce antibodies.
Inactivated viruses have been successfully used in the global fight against polio, and against other diseases like influenza. Scientists are now trying to use the same method to create an inactivated viral COVID antivaccine.
Potential Drawbacks:
The traditional approach is one of the slowest in terms of scalability since it requires growing a large number of viruses for use in the vaccine. It may not be ready in time to further slow down the pandemic and can be hard to make available on a global scale.
DNA Vaccine
How it Works
The technique used to engineer DNA vaccines involves injecting a plasmid, aka, a fragment of circular DNA, into human cells. In terms of SARS-CoV-2, this process will introduce the DNA codes for its viral proteins into the cell. The cell will then express those viral proteins and prime the immune system to fight off an attack from SARS-CoV-2.
Potential Drawbacks
Similar to the mRNA vaccine, DNA vaccines are a whole new territory. No such vaccines have been successfully developed and used in humans yet.
Viral Proteins
How it Works
The use of viral proteins is another traditional method for creating new vaccines. In this method, scientists get the genes that represent proteins from the pathogen – the notorious spike protein in the case of SARS-CoV-2. Those genes and proteins are then spliced into different viruses. One of the advantages of this method is that it can be mass-produced, which is a necessary component when dealing with a global pandemic.
Potential Drawbacks
Growing large amounts of viral proteins directly take time. When you need millions of doses as you do in a worldwide pandemic, the time crunch is a serious challenge.
Who’s in the COVID-19 Vaccine Race?
Many entities have thrown their hat into the ring, but the following are leading the efforts:
- Oxford University’s Jenner Institute
- Merck
- Johnson & Johnson via Janssen
- AstraZeneca
- Moderna
- BioNTEch
- CureVac
- Sinovac
- Inovio
- Sanofi Pasteur
These are some of the names to watch in the fight against the pandemic. Some of these companies are already massive conglomerates, but a few are start-ups which are starting to make a name for themselves in the industry.
Beyond COVID-19
While these vaccine candidates are focused on the COVID-19 pandemic, the technology and methods behind them have implications in the future. If the mRNA and DNA vaccines prove successful, for instance, they can pave the way for new vaccines that target other diseases. The adenovirus vaccine is another new technology that’s being tested for other diseases like Ebola and malaria. Beyond SARS-CoV-2, the success of these top five candidates and others that are yet to come can prove world-changing.
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