Pfizer's announcement Monday of a potentially effective coronavirus vaccine triggered a wave of hope and optimism, renewing some expectations that life in the U.S. could return to normal sometime in 2021.
Normal, however, is a ways away. Not every aspect of society will bounce back immediately, with rollouts of the vaccines starting with essential workers and plans dictating numerous phases of reopening, experts said.
And a vaccine, even one with promising early results, cannot do anything to stop a grueling winter, with outbreaks growing rapidly across the country and record hospitalization rates threatening to overwhelm health care resources.
Vaccines remain humanity's best hope of averting more widespread death and restoring society, but they cannot be looked at as an endpoint just yet.
"If a vaccine becomes available in April, that won't help us with the peak in the winter, what we're going to face in December and January," said Ali Mokdad, a professor of global health at the University of Washington and a former official at the Centers for Disease Control and Prevention. "We can celebrate good vaccine news, but we still have to be careful."
Mokdad said that even after a vaccine is rolled out, the country's ability to rebound will depend on the number of vaccines that can be secured and how they are distributed.
"The discussion automatically becomes: Do we want to save lives or livelihoods? If we have enough vaccines, we can do both," he said.
Most public health and infectious disease experts support a phased-in rollout that would ensure that those who need a vaccine the most get first dibs. But challenges with storing and shipping vaccines could mean delays as they are being disseminated.
"We have to prioritize and protect essential workers and the vulnerable first and then figure out how to broaden from there," said Dr. Stuart Ray, a professor of medicine at Johns Hopkins University.
The phased-in rollout is also meant to help kick-start the economy. Once enough people have been vaccinated, certain activities, such as going to the mall, eating in a restaurant or seeing a movie in a theater, may become safe once again.
"Normal life — or at least much more normal — now seems feasible in 2021," Ray said.
A report published last month by the National Academies of Sciences, Engineering, and Medicine included recommendations for how the first batch of vaccines could be earmarked. The guidelines covered four phases, with front-line health care workers and people at highest risk — those over age 65 and those with underlying health conditions that make them particularly vulnerable to severe Covid-19 — slated to receive the vaccine first.
The second phase, encompassing up to 35 percent of the U.S. population, would include teachers, child care workers and other "critical workers in high-risk settings," such as people with jobs in public transit or the food supply system.
The plan's third phase would cover children, young adults and people who work in industries that pose "moderately high risk of exposure," such as hotels, factories and universities. Under the fourth and final phase, anyone else residing in the U.S. who was not included in a previous phase would then have access to a vaccine.
Dr. Anthony Fauci, the government's top infectious disease expert, told CNN on Wednesday that a coronavirus vaccine could be available to all of the country by April.
Pfizer said Monday that it expects to produce up to 50 million vaccine doses globally this year and up to 1.3 billion doses next year. The U.S. government announced Wednesday that it has placed an initial order for 100 million doses and that it can acquire 500 million more doses. Volunteers in Pfizer's vaccine trial received two doses, which means the government's initial order would cover 50 million people.
And if it holds true that Pfizer's vaccine candidate — or any other potential vaccine in the works — is more than 90 percent effective at preventing infection, it could be slightly easier to protect the general population, said Dr. Paul Goepfert, a professor of medicine and microbiology at the University of Alabama at Birmingham.
A 90 percent effective vaccine would require vaccinating about 60 percent of the population to reach what is known as herd immunity, when enough people have developed antibodies from a vaccine or a previous Covid-19 infection that further community spread is unlikely.
"With measles, we have a 90 percent effective vaccine, too, but 12 to 14 people can get infected from one case if there's no immunity in a community, so you have to protect 90 percent of the population or you'll start seeing measles outbreaks," Goepfert said. "Fortunately, Covid is not that extreme — it's two to three infections from one case, so with a 90 percent effective vaccine, you don't have to vaccinate everybody."