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The past few weeks have been nothing but good news for COVID-19 vaccines. On Friday, Pfizer applied for emergency use authorization from the Food and Drug Administration (FDA) after announcing that its vaccine is 95 percent effective. Moderna isn’t far behind: The company plans to submit an application by the end of November for a vaccine that it says is 94.5 percent effective. Although authorization isn’t guaranteed, experts expect that the FDA will let Pfizer move forward with its treatment after an outside panel reviews its data on December 10. Moderna could follow shortly thereafter.

Even with these new vaccines, however, life won’t change very much—at least for the first few months. “You will still need to be mindful of masks and social distancing,” says Angela Shen, a research scientist at the Vaccine Education Center at the Children’s Hospital of Philadelphia, especially given that it’s still unknown how long COVID-19 immunity lasts after vaccination.

A slow rollout

Pfizer and its German partner company BioNTech are prepared to begin distributing the vaccine within hours after emergency approval. The companies plan to manufacture 50 million doses for global use by the end of 2020, while Moderna expects to have 20 million doses available in the US by the end of the year. That said, both vaccines require a second dose through a booster shot, so only 35 million US residents would get vaccinated by year’s end if all goes as planned.

Because there are limited doses, public health officials must prioritize who gets the vaccine first. Health care workers will probably be first in line, Shen says, followed by other essential workers and people who are at severe risk of COVID-19 complications, including those over 65. Exactly who is chosen will vary state by state. “Alaska looks much different than New York or California,” Shen says. “The population is different; the states are run differently; the delivery of healthcare is organized differently in terms of the number of large hospitals that you have and if you’re more rural. So each state’s plan will be different.”

Getting doses to the people who need them won’t be easy, either. Pfizer’s vaccine requires storage at -70 degrees Celsius, which is colder than Antarctica. That limits how people can access the treatment. “The first tranche of doses will most likely go into large health systems and hospital networks that have the ability to store at ultra cold temperatures,” Shen says. “We’re talking about well into 2021 before you can go down to your pharmacy the way you do for your flu shot or to go to your doctor’s office for a COVID vaccine.”

Moderna’s vaccine needs to be stored at -20 degrees Celsius, which is around the temperature of an everyday freezer. But handling it will still be a challenge. Both the Moderna and Pfizer formulas have finicky instructions, such as how often the dry ice keeping them cool needs to be replaced and how often each box of vaccines can be opened, Shen says. She adds that AstraZeneca’s vaccine, which the company recently announced is up to 90 percent effective, has much less stringent handling and storage requirements. However, it probably won’t be available in the US until more data is available from in-country trials next year.

As more vaccines earn emergency authorization from the FDA, more doses will be available for public use, free of charge. Shen predicts that most people won’t be able to get vaccinated against COVID-19 until spring of 2021—but William Moss, the executive director of the International Vaccine Access Center at Johns Hopkins Bloomberg School of Public Health, thinks that’s an optimistic timeline In the past, he says, companies have had to discard batches of vaccines due to contamination. It’s also possible that delayed side effects could crop up after authorization. If that happens and the health implications are serious, the vaccines could be pulled as researchers investigate the complications.

The resistance grows

Vaccines protect the people who get them, but their more important function is to protect the community as a whole from getting sick. Most experts estimate that a population will reach herd immunity against COVID-19 when 50 to 70 percent of people have built up enough antibodies to neutralize the virus, Moss says. People who’ve had the disease may be immune to reinfection for months or years, which drives down the number who need to be vaccinated to reach this goal. However, no vaccine is 100 percent effective, so a majority of the country will still need to get immunized to reach the threshold. This will be a challenge because many US residents are wary of vaccines—especially a vaccine developed so quickly, Shen says. In a Gallup survey released at the beginning of November, only 58 percent of Americans said they were willing to get a COVID-19 vaccine.

Reaching herd immunity also won’t end the pandemic immediately. “Many people have this misconception that once this kind of magical threshold is reached, the virus just kind of goes away,” Moss says. Daily cases, hospitalizations, and deaths will decrease, but the disease could still spread in low levels year-round. Or, it may become seasonal like the flu and many other respiratory illnesses.

As the COVID-19 declines, life might finally return to normal in stages. Smaller businesses such as restaurants and hair salons would fully open first, Moss says. Then, if cases stay down, larger public venues like concert halls and sports stadiums would reopen. Precautions may become less universal and more targeted—for example, places that draw lots of older people (think health care facilities) may require masks until it’s clear the risk of community transmission is low. This could be the case well into 2022, depending on how the virus behaves, Moss says.

Until then, pandemic precautions will probably be necessary. “Life should get better,” Shen says, “but you shouldn’t let your guard down.”

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