What does emergency use of a COVID-19 vaccine mean? It’s when regulators allow shots to be given to certain people while studies of safety and effectiveness are ongoing. Before any vaccine is permitted in the U.S., it must be reviewed by the Food and Drug Administration, which requires study in thousands of people. Normally, the process to approve a new vaccine can take about a decade. But the federal government is using various methods to dramatically speed up the process for COVID-19 vaccines.
During a health crisis, the FDA can loosen its normal scientific standards to allow emergency use of experimental drugs, devices, vaccines and other medical products. The first vaccines to get the provisional green light in the U.S. are almost certain to be made available under this process, known as emergency use authorization.
Instead of the usual requirement of “substantial evidence” of safety and effectiveness for approval, the FDA can allow products onto the market as long as their benefits are likely to outweigh their risks. It has already used its emergency powers to authorize hundreds of coronavirus tests and a handful of treatments during the pandemic.
But the agency has almost no experience granting emergency use for vaccines and has laid out extra standards it will use to make decisions on upcoming COVID-19 shots.
In October, FDA officials told vaccine makers they should have two months of safety follow-up from half of the people enrolled in their studies before requesting emergency authorization. That data is expected to be enough for FDA to allow vaccinations of certain high-risk groups, such as front-line health workers and nursing home residents.
Full approval of a vaccine will likely require six months of safety follow-up as well as extensive inspections of company manufacturing sites. The leading vaccine makers are not expected to complete that process until next spring or summer. Only then is the FDA expected to grant full approval, which would allow vaccinations of the general population.
What does COVID-19 vaccine effectiveness mean?
It refers to the likelihood that a coronavirus shot will work in people.
Two vaccine makers have said that preliminary results from their late-stage studies suggest their experimental vaccines are strongly protective. Moderna this week said its vaccine appears nearly 95% effective. This comes on the heels of Pfizer’s announcement that its shot appeared similarly effective.
Effectiveness numbers will change as the vaccine studies continue since the early calculations were based on fewer than 100 COVID-19 cases in each study. But early results provide strong signals that the vaccine could prevent a majority of disease when large groups of people are vaccinated.
U.S. health officials said a coronavirus vaccine would need to be at least 50% effective before they would consider approving it for use. There was concern that coronavirus vaccines might be only as effective as flu vaccines, which have ranged from 20% to 60% effective in recent years.
The broad, early effectiveness figures don’t tell the whole story. Scientists also need to understand how well the vaccine protects people in different age groups and demographic categories.
For both vaccines, the interim results were based on people who had COVID-19 symptoms that prompted a virus test. That means we don’t know yet whether someone who’s vaccinated might still get infected -- even if they show no symptoms -- and spread the virus.
Also unknown is whether the shots will give lasting protection, or whether boosters will be required.
Who will be the first to get COVID-19 vaccines?
No decision has been made, but the consensus among many experts in the U.S. and globally is that health care workers should be first, said Sema Sgaier of the Surgo Foundation, a nonprofit group working on vaccine allocation issues.
An expert panel advising the U.S. Centers for Disease Control and Prevention is also considering giving high priority to workers in essential industries, people with certain medical conditions and people age 65 and older.
Once a vaccine gets a green light from the Food and Drug Administration, the panel will look at clinical trial data on side effects and how people of various ages, ethnicities and health statuses responded. That will determine the panel’s recommendations to the CDC on how to prioritize shots.