When will a Covid-19 vaccine be available to the public?
No one's sure yet, but the target is sometime in early 2021. Vaccines in development around the world are in various stages of testing. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said he's confident one of the vaccine candidates will be proven safe and effective by the first quarter of 2021. However, it's not clear which candidate shows the greatest promise yet.
Why does it take so long to develop a vaccine?
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, said Dr. Emily Erbelding, an infectious disease expert at the NIAID.
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 will begin:
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: This phase increases the number of participants -- often into the hundreds -- for a randomized trial. More members of at-risk groups are included. If the results are promising, the trial moves to:
Phase 3: This phase tests for efficacy and safety with thousands (or tens of thousands) of people. The substantially larger number of participants in this phase helps researchers learn about possible rare side effects from the vaccine.
What are the dangers of rushing the process?
History has shown that vaccines developed or distributed in a hurry can lead to unintended consequences:
So how do we safely speed up the process?
Scientists are trying to find safe ways of speeding up the typical processes. For example:
-- In Seattle and Atlanta, researchers planned to test animals and humans at the same time, instead of animals before humans, according to the health news website Stat.
-- Some vaccines could be mass produced before the trials have even finished.
If the vaccine trials are successful, millions of doses would be ready to go -- potentially saving lives immediately instead of waiting months for production to ramp up. But if the trials aren't successful, the stockpile of pre-made vaccines could go to waste.
How effective or long-lasting will the vaccine be?
Not all vaccines are created equal. If you get vaccinated against polio, you're probably protected for life. But if you get a flu shot, you might still get the flu that season (though probably with less severe symptoms). And you'll need a different flu shot the next season. Researchers say at this point, there's no way to predict how effective or long-lasting a novel coronavirus vaccine would be.