What an unprecedented year everyone! All of us are waiting eagerly for the COVID Vaccine to help us fight this notorious virus. When will the vaccine come? How effective will it be? How does it really work? Let me try to answer some of those queries as simply as I can.
 
But first of all, Understand How vaccine development usually works?
The vaccine has to go through the following stages before it gets approved:
PRE-CLINICAL – Animal trial – approx 2 years
PHASE 1- SAFETY trial – approx 2 years
PHASE 2 – Large group trial – 2-3 years
PHASE 3 – Efficacy trial – 5-10 years
APPROVAL- Regulators Approve
PRODUCTION
It can typically take 10 to 15 years to bring a vaccine to market; the fastest-ever—the vaccine for mumps—required four years in the 1960s.
More than 150 coronavirus vaccines are in development across the world—and hopes are high to bring one to market in record time to ease the global crisis.
 
So how does COVID Vaccine work?
Currently, there are three main types of COVID-19 vaccines that are or soon will be undergoing large-scale (Phase 3) clinical trials. Below is a description of how each type of vaccine works. None of these vaccines can give you COVID-19.
1-mRNA vaccines: contain material from the virus that causes COVID-19 that gives our cells instructions for how to make a harmless protein that is unique to the virus. After our cells make copies of the protein, they destroy the genetic material from the vaccine. Our bodies recognize that the protein should not be there and build T-lymphocytes and B-lymphocytes that will remember how to fight the virus that causes COVID-19 if we are infected in the future.
2- Vector vaccines: contain a weakened version of a live virus—a different virus than the one that causes COVID-19—that has genetic material from the virus that causes COVID-19 inserted in it (this is called a viral vector). Once the viral vector is inside our cells, the genetic material gives cells instructions to make a protein that is unique to the virus that causes COVID-19. Using these instructions, our cells make copies of the protein. This prompts our bodies to build T-lymphocytes and B-lymphocytes that will remember how to fight that virus if we are infected in the future.
3- Protein subunit vaccines: include harmless pieces (proteins) of the virus that cause COVID-19 instead of the entire germ. Once vaccinated, our immune system recognizes that the proteins don’t belong in the body and begins making T-lymphocytes and antibodies. If we are ever infected in the future, memory cells will recognize and fight the virus.
 
The other 3 types that have not made to stage 3 trials yet are:
1- Live attenuated virus: A live attenuated virus is constructed by mutating the original virus. The mutation creates a weaker virus that cannot cause significant harm to the body.
2- Inactivated Virus: An inactivated vaccine is produced by disabling a virus through radiation, chemicals, or heat. The inactive virus cannot cause disease because it is not trying to enter cells and replicate.
3- Virus-like Particles: Virus-like particle vaccines closely resemble the coronavirus in structure but contain none of its genetic material. It’s like an empty shell that looks like the coronavirus but isn’t capable of doing damage to the body.
 
So which vaccine are we getting and when?
Though it’s too soon to say which candidates will ultimately be successful, here’s a look at the prospects that have reached phase three and beyond—including a quick primer on how they work and where they stand.
 
1- Pfizer
Name: BNT162b2 – mRNA vaccine
Completed phase 3 trial- Ready to be launched
This vaccine is based on injecting mRNA into human cells. It spurs the production of viral proteins that mimic the coronavirus, training the immune system to recognize its presence. Any successful vaccine based on this technology would be the first mRNA vaccine approved for human use. This vaccine requires two doses taken 21 days apart.
On November 20, Pfizer and BioNTech said they were filing for emergency authorization from the FDA just two days after announcing the conclusion of their phase three trials.
So this might be the first vaccine out, but they have yet to provide underlying data to back the claim, and it’s still unclear if the vaccine produces a durable immune response. The companies also haven’t explained if the vaccine works by reducing disease symptoms or blocking the virus entirely.
Pfizer expects to be able to produce up to 50 million vaccine doses in 2020 and 1.3 billion doses by the end of 2021. Questions have been raised over the vaccine’s storage, which requires ultra-cold freezers set at minus 70 degrees Celsius (minus 94 degrees Fahrenheit).
 
2- University of Oxford
Name: ChAdOx1 nCoV-19 – The Viral vector vaccine
Currently in Phase 3 trial- expected Early 2021
Oxford’s research team has transferred the SARS-CoV-2 spike protein—which helps the coronavirus invade cells—into a weakened version of an adenovirus, which typically causes the common cold. When this adenovirus is injected into humans, the hope is that the spike protein will trigger an immune response. AstraZeneca and Oxford plan to produce a billion doses of vaccine that they’ve agreed to sell at cost.
On November 18, preliminary results from Oxford’s phase two trials, showing that the vaccine produced strong immune responses across all adult age groups, including older adults who are more vulnerable to the disease. Early results also revealed that the vaccine had triggered a strong immune response—including increased antibodies and responses from T cells—with only minor side effects such as fatigue and headache.
The phase three trial now aims to recruit up to 50,000 volunteers in Brazil, the United Kingdom, the United States, and South Africa, Brazil and India.
 
3- Sinovac
Name: CoronaVac – Inactivated virus vaccine
Currently Phase 3 trial, expected Early 2021
 
4- Moderna Therapeutics
Name: mRNA-1273 – mRNA vaccine
Currently, Phase 3, expected in Early 2021
 
5- Bharat Biotech
Name: COVAXIN- Inactivated virus vaccine
Will start Phase 3 trial, expected Middle or late 2021
 
There are half a dozen other companies, currently in their 1st or 2nd phase of trials of vaccine development and we are yet to determine their safety and efficacy.
With what is evident, the preferred COVID vaccine will change and continue to develop in the next 1-2 years. What comes first, might not be the most effective vaccine, but will still reduce the overall infective load.