What Is a Coronavirus Vaccine?

A coronavirus vaccine is a theoretical treatment that would prepare a person's immune system for a select strain of coronavirus, thereby reducing their risk of infection.
At the time of writing this article, there are no vaccines for the notable human coronavirus strains SARS-CoV-1, MERS, or SARS-CoV-2. 

How would we develop a human coronavirus vaccine?

A vaccine works by providing an immune system with material it can use to set up an effective response against a specific pathogen much faster than usual, preventing invading particles from developing into an infection. 
In the past, vaccines were based on pathogens grown in animals, or in eggs, before being harvested and weakened to prevent them from growing into an infection. These dead or injured disease particles could then be injected into a host, often with added ingredients to help kick the immune system into action.
This process can be slow and potentially risky. Developing a vaccine today requires researchers to identify which components will be recognisable enough to an immune system to trigger it into activating without generating serious side-effects or giving rise to debilitating symptoms.
To ensure a high level of efficacy and safety, researchers now tend to start by studying the genome and chemical characteristics of the pathogen.
Recombinant vaccines, for instance, involve isolating sections of the genome that encode a single piece of the pathogen and combining it with a cell culture to produce sufficient material for a vaccine. 
An RNA vaccine is an even more recent technology. It involves inserting a similar section of genome in the form of RNA directly into a target's body, using their own cells to produce a piece of the pathogen for the immune system to recognise. 
If no significant problems are spotted in pre-clinical trials, this vaccine can then be tested on human volunteers for safety, and then again in a larger group to see if it's effective.
The whole process can take years and a large amount of resources, with no guarantee that it will succeed in managing an outbreak in a population.

Why don't we have a coronavirus vaccine yet?

While there are vaccines for several types of coronavirus that typically infect livestock, such as porcine respiratory CoV, a vaccine for the more notorious strains that impact humans is yet to be developed.
Research into a vaccine to prevent infections by the coronavirus SARS-CoV-1 commenced soon after the 2003 outbreak of severe acute respiratory syndrome (SARS). In spite of repeated attempts over the years to develop a preventative treatment, no potential vaccine has been found to be both safe and effective in preliminary clinical trials.

Today, it still isn't clear why the preliminary vaccines produced such serious health concerns in animals, or what the effects might potentially be in humans.
With the strains responsible for SARS and MERS no longer a global threat and costs for testing so high, interest in (and funding for) coronavirus vaccines quickly subsided after the 2003 outbreak.

When will there be a vaccine for SARS-CoV-2?

Since the global spread of the novel coronavirus, SARS-CoV-2, interest in finding a coronavirus vaccine has once again spiked. Dozens of labs around the world are in the early stages of developing potential vaccines.
While genetic sequencing for the first SARS coronavirus took months to complete, the most recent coronavirus genome was released by Chinese researchers just days after the World Health Organisation officially declared the appearance of the new virus.
This has led some research labs to attempt to develop recombinant vaccines based on sequences of the virus's receptors. While the concept sounds simple, each stage of testing can still take many months, while producing enough vaccines would potentially add even more time.

Other research bodies are investigating the possibility of developing an RNA vaccine, a procedure that could be faster to develop but slower to roll out in large numbers. 
A safe method for introducing the genes into our cells would also be required. Regulatory bodies such as the FDA are also yet to give the all clear to a single vaccine based on this principle.
With so many questions remaining on SARS-CoV-2 vaccine safety, methods of manufacture, and delivery, it's impossible to say when we might begin to manage the COVID-19 pandemic with a vaccine program. Animal trials are underway for some, with potential early human testing by mid year.
Still, unprecedented science moving at an unprecedented pace still takes time.

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