Scientists around the world are racing against time to develop a vaccine for the novel coronavirus that has killed more than 100,000 people and infected more than 1.7 million worldwide.
In some of the worst affected countries such as China and Italy, the infections and deaths have levelled off in recent days, but experts warn the risk of a new wave of outbreaks is imminent without a vaccine.
But the expedited development of a vaccine remains a lengthy process, often taking years, with many scientific hurdles despite serious and coordinated international efforts by laboratories, private companies and governments.
Experts say a vaccine for the new coronavirus, SARS-CoV-2, could take at least a year to a year and a half to be proven safe, effective and made widely available.
To date, the World Health Organization (WHO), says three vaccine candidates are in the clinical testing phase, meaning they are able to be tested on humans, while 67 potential vaccines are in preclinical phase.
This is where the world stands on a vaccine for the new coronavirus:
A vaccine works by presenting certain molecules, also known as antigens of the pathogen (the virus), to the human body’s immune system, Dr Sara Kayat explained in an Al Jazeera Doctor’s Note.
These antigens are traditionally in a weakened or inactive form, so they cannot actually cause the illness. However, our immune system is able to recognise the antigen as an unwanted foreign invader, and thus forms antibodies that reject the pathogen if it tries to infect you in the future.
Many potential vaccines being developed, including one of the three which the WHO says is in the clinical testing phase, use this more traditional approach.
Newer science is also being employed to create vaccines from a copied genetic code from the virus, which is made in a laboratory. At least two potential vaccines made this way are currently being tested on humans. However, no vaccine that has been made in this novel fashion has been approved to date for any sickness.
Scientists have a bit of a head start in creating a vaccine for the virus that causes COVID-19, according to Dr Kayat.
Because of genome sequencing of the new coronavirus provided by scientists in China, scientists know it shares 79 percent of the same genetic material as SARS, and 50 percent of the same material as MERS. This allows developers to use groundwork already created in research for vaccines for those viruses.
Vaccine testing typically begins with animal testing, although at least one coronavirus vaccine developer has skipped this step and moved straight to human testing, and others have done parallel human and animal testing.
The human testing is usually composed of three phases.