Seeing people wearing masks in everyday life is now the norm throughout much of the country — something that was uncommon in the United States until the coronavirus pandemic began in March.

Over the course of 2020, we’ve learned that wearing a mask protects yourself and others from the coronavirus, underscoring the importance of wearing a mask while in public or close settings.

Mask-wearing, hand-washing and social distancing remain key to curbing the spread of the virus, but much has changed in the world of COVID-19 prevention. Notably, there is now at least one approved vaccine in several countries, including the U.S., the United Kingdom and Canada. But while a vaccine is a profound scientific development that provides much-needed safety, it is not an immediate cure-all.

Realistically, immunity is not achieved immediately after vaccination and the vaccine won’t be available to everyone at the same time. So, even after high-risk individuals and other groups are vaccinated, important mitigation measures like mask-wearing will continue.

“I think we should be prepared to wear masks for the foreseeable future, probably for the next year, certainly into that third quarter of 2021 when they expect to really be able to vaccinate large numbers of the general public,” said Marybeth Sexton, assistant professor of infectious diseases at Atlanta’s Emory University School of Medicine.

Why? Here are the reasons face masks will be necessary as the vaccine rollout continues, according to experts:

While the vaccine is highly effective, it won’t result in immunity for everyone

Data from the vaccine trials showed that both the Pfizer and Moderna vaccines are very effective — most people who get the vaccine will receive protection against the coronavirus.

While the efficacy data for the Pfizer vaccine reports that it’s 95% effective ― higher than most experts originally expected ― that does mean that there is still a portion of the vaccinated population that won’t be protected, Sexton said.

“You have 5% of people, and potentially more in certain groups, who may not be immune despite having gotten vaccinated,” she said, adding that it is also unknown how those who are immunocompromised will respond to the vaccine and whether it will be 95% effective among that group, too.

Wearing masks will be necessary to protect those who do not develop protection from COVID-19 until herd immunity can be achieved. “We estimate that you need somewhere from 60 to 70% of the population to be immune to have herd immunity,” Sexton noted.

She added that it will take time to achieve herd immunity, especially with a new, two-dose vaccine.

It’s unknown whether people who receive the vaccine can still spread the virus

You might read the first point and think: What does it matter as long as I’m vaccinated? I won’t be able to spread the disease to someone who isn’t protected. That, sadly, is not decidedly known yet, said Michael LeVasseur, assistant professor in epidemiology and biostatistics at Drexel University’s Dornsife School of Public Health.

“There are still questions as to whether or not someone who has been vaccinated can get an infection that results in secondary infections,” LeVasseur noted. In other words, people who receive the vaccine may still be able to pass the infection to those around them.

He added that people are most infectious before they show any COVID-19 symptoms, so it’s not outside the realm of possibility to worry that asymptomatic spread could happen if those who receive the vaccine can still shed the virus.

Dr. Anthony Fauci — the nation’s top infectious diseases expert — told the “Today” show on Friday that it appears Moderna’s vaccine may prevent someone from spreading the infection. However, more time is needed to study people who receive the vaccine to determine if that’s actually the case.

“If you protect against clinical disease, that’s very good,” Fauci said in the interview. “But if you also even prevent a person from getting actually infected, that would mean that you’re preventing someone from passing the infection on to someone else, and that kind of interferes with the chain of transmission.”

Sexton added that more questions around spread in vaccinated individuals will be answered as we learn more about the vaccines. Until then, masking will still be important to make sure those who are protected don’t spread the virus to those who have not yet been vaccinated.

Immunity won’t occur immediately, making masks necessary as your body responds to the vaccine

The current approved COVID-19 vaccines and the vaccine candidates are given in two doses. You’ll need to get two shots three to four weeks apart to complete your treatment. On top of that, immunity won’t happen as soon as you leave the doctor’s office.

“You’re probably not going to achieve the levels of immunity required to prevent infection for 28 days, depending on the vaccine,” LeVasseur said, adding that 28 days is roughly a week after the second vaccine dose.

Masks will be necessary to protect yourself and others against the spread of COVID-19 as your body responds to the vaccine.

And while some people will get the vaccine soon, many won’t be able to get the vaccine well into 2021. This makes wearing masks in public spaces and enclosed areas crucial to keeping everyone healthy as they wait for their turn to get vaccinated.

The amount of time we’ll have to wear masks depends on how much of the population gets vaccinated

There is still some public hesitation around the coronavirus vaccine. An estimated 63% of Americans say they will get the vaccine, according to a December Gallup poll, LeVasseur said.

Sexton stressed that it’s crucial that people pay attention to the science coming out of the trials, which shows that the vaccine works well and has good safety data.

People’s willingness or unwillingness to get the vaccine directly affects how long we will have to wear masks and wait for a return to “normal,” Sexton said. It’s impossible to achieve any sort of public immunity if people are not willing to get the vaccine.

Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.