The Covid-19 pandemic has triggered an urgent global effort to develop a vaccine. There is, however, consensus among experts that the earliest one could be made available for public deployment is 12 to 18 months from now.
This would certainly be unprecedented.
It took four years to develop a vaccine for mumps and five to get a vaccine for Ebola. No vaccine has ever been developed faster before or since.
The usual development timeline for a vaccine is around 10 to 15 years. In some cases, such as with the HIV virus, efforts to find a vaccine have failed.
BALANCING HOPE WITH REALISM
"Science is science, and we have to be realistic," says Dr Maria Elena Bottazzi, associate dean of the National School of Tropical Medicine at Baylor College, which is working to develop a vaccine.
"To tell people in 12 to 18 months we're going to have a vaccine without having the evidence raises hopes," Dr Bottazzi said.
"The reality is we have never done it before. But today, we may be better positioned than maybe five years ago because we have better technology (and) we have had previous experiences with Sars and Mers, so maybe that also can help us," she added.
The severe acute respiratory syndrome (Sars) emerged in China in 2003 and Middle East respiratory syndrome (Mers) in the Arabian peninsula in 2012. Both are coronaviruses with high fatality rates, but new cases are rare.
"We need to keep high trust that it is possible, but we also don't want to do it too fast in case it damages people and damages the trust that vaccines are the best public health intervention as long as they are done with all the safety protections, and we make sure we evaluate carefully the efficacy of the vaccine," Dr Bottazzi said.
UNPRECEDENTED SCALE, SPEED
At least eight Chinese institutes and companies are reportedly involved in the research and development of a Covid-19 vaccine.
A paper published in Nature gave an overview of the global Covid-19 vaccine research and development landscape as of April 8.
It noted that the global vaccine R&D effort in response to the Covid-19 pandemic is unprecedented in terms of scale and speed, and that a vaccine could be available by early next year.
Q&A on vaccines
Q Why does it take so long to develop a vaccine?
A It normally takes an average of 10 to 15 years to develop a vaccine because doctors and researchers have to ensure that the treatment is safe for a large number of people to use.
Vaccines must go through several phases of development - including pre-clinical studies, animal testing, human clinical trials and quality control - before they can be approved for use.
Other factors include how complex the disease is and how the human immune system reacts to it.
Q Which countries are involved in this effort?
A The quest for a vaccine for the new coronavirus has involved numerous countries around the world, including Singapore, China, the United States, Britain, Germany, France and Australia.
There are 70 coronavirus vaccines in development globally, with three candidates already being tested in human trials, according to the World Health Organisation (WHO).
The furthest along in the clinical process is an experimental vaccine, which is in phase two, developed by Hong Kong-listed CanSino Biologics and the Beijing Institute of Biotechnology.
The other two being tested in humans are treatments developed separately by US biotechnology companies Moderna and Inovio Pharmaceuticals, according to the WHO.
Q Why are private companies, not governments, at the forefront?
A For one thing, private companies are often not subject to the extent of bureaucracy faced by many governments around the world. They are also motivated by the potential for profit.
Being able to come up with any inroads into developing a coronavirus vaccine at this time can ensure coveted government funding for the private firm's costly research and possibly secure exclusive licences to develop and sell the drug further down the road.
Q Are there vaccines for most viral diseases?
A There are still no vaccines for many viral diseases, such as severe acute respiratory syndrome and Middle East respiratory syndrome.
It can take months for scientists to determine just the genome sequence of the virus. By the time human trials can be conducted, outbreaks may already be over, and governments' priorities may have changed.
A lack of recurrence after an outbreak also means less data is available for research, and makes it less worthwhile for firms to continue pursuing a vaccine.
• Additional reporting from Bloomberg
According to the paper's authors, there are 78 confirmed active projects, 73 of which are currently at exploratory or pre-clinical stages.
"The most advanced candidates have recently moved into clinical development, including mRNA-1273 from Moderna, Ad5-nCoV from CanSino Biologicals, INO-4800 from Inovio, LV-SMENP-DC and pathogen-specific aAPC from Shenzhen Geno-Immune Medical Institute," the paper said.
The authors stressed that it will be important to ensure coordination of vaccine manufacturing and supply capability and capacity to meet demand.
PHASE ONE TRIAL
Several vaccine developers have plans for human testing this year. One of them is the Emory Vaccine Centre at the Emory University School of Medicine in Atlanta, Georgia.
Emory University is one of 10 sites that have facilitated testing of vaccines and therapeutics for infectious diseases for decades. It is currently in phase one trials of a vaccine.
Dr Nadine Rouphael, associate professor at the Division of Infectious Diseases at the Emory University School of Medicine, told The Straits Times that in this phase one trial - the first time the vaccine has been given to humans - 45 subjects between 18 and 55 will be enrolled.
"They will receive two doses, separated by four weeks. And really the idea here is to make sure that this vaccine is safe.
"We will also gather information about how their immune system will respond to the vaccine in preparation for future phase two and phase three trials.
"We don't know if the vaccine can protect from infection. But we're checking to make sure it's safe," said Dr Rouphael.
VACCINE DEVELOPMENT IN CHINA
China announced on Tuesday that it has given the go-ahead to two more vaccine makers to carry out early-stage human testing.
They are the Beijing subsidiary of Nasdaq-listed Sinovac Biotech and pharmaceutical company Sinopharm, which is working with the Wuhan Institute of Virology.
Last month, the Chinese authorities approved clinical trials for a vaccine candidate by the People's Liberation Army's Academy of Military Sciences and biotech firm CanSino Bio, the first and only vaccine in the world that moved into the second phase of a human trial last week.
The two new candidates are the first inactivated vaccines to start trial globally.
"It should be said that the production process (for inactivated vaccines) is relatively mature, the quality standards are controllable, the scope of protection is also relatively wide," said Ministry of Science and Technology official Wu Yuanbin at a news conference on Tuesday.
"These will provide some conditions for accelerating the use of vaccines."
At least eight Chinese institutes and companies are said to be involved in the research and development of a vaccine for Covid-19.
The Chinese Centre for Disease Control and Prevention said on Jan 26 that the country had started developing vaccines after the virus was isolated and the seed strains screened.
"We must be aware that the development of a vaccine is a battle that China cannot afford to lose," said a Global Times op-ed last month.
"Future competition between countries will be essentially a competition of technological strength.
"Only by mastering advanced technologies can a country be able to hold its development and national security in its own hands.
"From this aspect, it is not exaggerated to call vaccine R&D a life-and-death battle."
Analysts say the Chinese military has a distinct advantage over the rest in the development of vaccines, given its access to samples and data, and the complete backing of the state.