Coronavirus pandemic: Why does it take so long to develop a vaccine?
Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in the US, said he hopes to have "a couple hundred million doses" by the start of 2021. As of early June, there were more than 120 candidate vaccines for COVID-19, the World Health Organization said.
The world is continuing to fight the deadly coronavirus pandemic and scientists are racing against the clock to find an antidote for COVID-19, but the details and timelines to devlop one keep shifting. The highly-contagious disease has so far infected more than 7 million across the world and killed over 405,000 people, according to a Johns Hopkins University tally.
So let's find out why does it take so long to develop a vaccine.
According to Dr Emily Erbelding -- an infectious disease expert at the National Institute of Allergy and Infectious Diseases (NIAID) in the US -- vaccines have to go through multi-phase trials to make sure they're effective and safe.
Typically, a vaccine takes eight to 10 years to develop, she says.
Here's how the process typically works:
First, a vaccine is usually tested in animals before humans. If the results are promising, a three-phase trial in humans begins.
In Phase 1, the vaccine is given to a small group of people to assess safety and, sometimes, immune system response. If things go well, researchers move on to Phase 2.
The next phase increases the number of participants -- often into the hundreds -- for a randomized trial. More members of at-risk groups are included.
According to the Centers for Disease Control and Prevention: "In Phase II, the clinical study is expanded and vaccine is given to people who have characteristics (such as age and physical health) similar to those for whom the new vaccine is intended." If the results are promising, the trial moves to further stage.
In Phase 3, tests for efficacy and safety with thousands (or tens of thousands) of people are conducted. The substantially larger number of participants in this phase helps researchers learn about possible rare side effects from the vaccine.
WHEN WILL A COVID-19 VACCINE BE AVAILABLE TO PUBLIC?
According to Dr Anthony Fauci, the director of NIAID, the target is sometime in early 2021. He said that vaccines in development around the world are in various stages of testing and added that he's confident one of the vaccine candidates will be proven safe and effective by the first quarter of 2021.
A report in the New York Times last week had said that the Donald Trump administration selected five companies, including Moderna Inc, AstraZeneca Plc and Pfizer Inc, as the most likely candidates to produce the vaccine for the highly-contagious disease.
The other companies are Johnson & Johnson and Merck & Co Inc, according to the report in the Times. The US government is helping these companies ramp up development of their candidate vaccines so that if they're proven to work safely, they can be rolled out quickly.
"By the beginning of 2021, we hope to have a couple of hundred million doses," Fauci said. He said one vaccine candidate, made by the biotech company Moderna in partnership with NIAID, should go into a final stage of trials by mid-summer.
The plan is to manufacture doses of the vaccine before it is clear whether they work, making close to 100 million doses by November or December.
Scientists should have enough data by November or December to determine if the vaccine works, Fauci added.
Another vaccine candidate, made by AstraZeneca, is underway in the UK and will follow a similar schedule. Dr Francis Collins, director of the National Institutes of Health, said: "If all goes well, maybe as many as 100 million doses by early 2021" would be possible.
But as per many doctors, getting an effective vaccine out by January is a "highly ambitious goal", CNN reported. "Everything will have to go incredibly perfectly if that's going to happen," said Dr Larry Corey, an expert in virology, immunology and vaccine development.
"No vaccine is going to be put forward unless it's been checked out very thoroughly, both in terms of 'Is it safe?' and 'Does it protect you?'" said Collins.
Scientists are trying to find safe ways of speeding up the typical processes. Dozens of research teams from around the world are working to develop or test coronavirus vaccines.
According to the World Health Organization, as of early June, there were more than 120 candidate vaccines. Some are farther along in their trials than others. As of June 4, 10 vaccine candidates were in human trials -- four in the US, five in China, and one in the UK, the UN agency said.
But scientists do say that there is no guarntee that there will an effective COVID-19 vaccine.
"There are some viruses that we still do not have vaccines against," said Dr David Nabarro, a professor of global health at Imperial College London. "We can't make an absolute assumption that a vaccine will appear at all, or if it does appear, whether it will pass all the tests of efficacy and safety."