As the new COVID-19 vaccines begin to roll out, we’re sure you have thousands of questions. Here are the some of the questions we’re most curious about and answers we were able to find during our deep dig.

How will the rest of us get vaccinated?

When the vaccine is more widely available, shots will be handed out similarly to flu shots — through clinics and pharmacies.

It’s likely that when the general public starts getting vaccinated in April, shots will be scheduled through doctors’ offices, CVS, Walgreens and other pharmacies — the same way people get flu shots. However, final plans will depend on what other vaccines besides Pfizer’s and Moderna’s have been approved.

Can I choose which vaccine I get?

This depends on a number of factors, including the supply in your area at the time you’re vaccinated and whether certain vaccines are found to be more effective in certain populations, such as older adults. At first, the only choice will be Pfizer’s vaccine, though Moderna’s could become available within weeks.

How long will it take to work?

You won’t get the full protection from the Pfizer-BioNTech vaccine until about a week after the second dose, based on clinical trial data. The researchers found that the vaccine’s protection started to emerge about ten days after the first dose, but it only reached 52% efficacy, according to a report in the New England Journal of Medicine. A week after the second dose, the efficacy rose to 95%.

Will it hurt? What are the side effects?

The injection into your arm won’t feel different than any other vaccine, but the rate of short-lived side effects does appear higher than a flu shot. Tens of thousands of people have already received the vaccines, and none of them have reported any serious health problems. The side effects, which can resemble the symptoms of Covid-19, last about a day and appear more likely after the second dose. Early reports from vaccine trials suggest some people might need to take a day off from work because they feel lousy after receiving the second dose. In the Pfizer study, about half developed fatigue. Other side effects occurred in at least 25 to 33% of patients, sometimes more, including headaches, chills and muscle pain.

While these experiences aren’t pleasant, they are a good sign that your own immune system is mounting a potent response to the vaccine that will provide long-lasting immunity.

If I have allergies, should I be concerned?

People with severe allergies who have experienced anaphylaxis in the past should talk to their doctors about how to safely get the vaccine and what precautions to take. Although severe reactions to vaccines are rare, two health care workers had anaphylaxis after receiving the vaccine on the first day it became available in Britain. Both workers, who had a history of severe reactions, were treated and have recovered. (Anaphylaxis can be life-threatening, with impaired breathing and drops in blood pressure that usually occur within minutes or even seconds after exposure to a food, medicine or substance like latex.) For now, British authorities have said the vaccine should not be given to anyone who has ever had an anaphylactic reaction, but U.S. health experts have said such warnings are premature because severe reactions can be treated or prevented with medications.

What will happen if serious side effects crop up after the vaccine is rolled out?

Once a vaccine starts to reach large numbers of people, it’s possible (and not uncommon) for a small number of severe “adverse events” to occur. Many existing vaccines, including the flu shot, also can cause rare complications, including Guillain–Barré syndrome, seizures and sudden unexplained death. While this sounds frightening, the risk is minuscule when considered over the millions of people who are safely vaccinated each year, and some of these complications can be triggered by the virus itself. Health officials will investigate each event to see if it’s simply coincidence — or if it could have been caused by the vaccine. While everyone should be prepared to hear about these reports, they should not be a cause for worry or prompt you to delay getting the vaccine. Your risk of severe complications from Covid-19 is far higher than your risk of complications from the vaccine.

I had Covid-19 already. Do I need the vaccine?

It’s safe, and probably even beneficial, for anyone who has had Covid to get the vaccine at some point, experts said. Although people who have contracted the virus do have immunity, it is too soon to know how long it lasts. So for now, it makes sense for them to get the shot. The question is when. Some members of the C.D.C. advisory committee have suggested people who have had Covid in the past 90 days should be toward the back of the line.

What about women who are pregnant or breastfeeding?

Pregnant and breastfeeding women should consult with their obstetricians and pediatricians about whether to get the vaccine. The Pfizer vaccine has not been tested in pregnant women or in those who were breastfeeding, and federal health officials have not issued any specific guidance, other than allowing these women to be vaccinated if they choose. (The American College of Obstetricians and Gynecologists issued practice guidelines to help women.)

Does the vaccine affect fertility or miscarriage risk?

A false claim has been circulating online that the new vaccine will threaten women’s fertility by harming the placenta. Here’s why it’s not true.

The claim stems from the fact that the vaccines from Pfizer and Moderna cause our immune systems to make antibodies to something called a “spike” protein on the coronavirus. The false warnings about fertility are based on the claim that these antibodies could also attack a similar protein that is made in the placenta during pregnancy, called syncytin. In reality, the spike protein and syncytin are similar only in one very small region, and there’s no reason to believe antibodies that can grab onto spike proteins would lock onto syncytin.

What’s more, the human body generates its own supply of spike antibodies when it fights off the coronavirus, and there’s no sign that these antibodies attack the placenta. If they did, you’d expect that women who got Covid-19 would suffer miscarriages. But a number of studies show that Covid-19 does not trigger miscarriages. doctors talk about vaccination.)

When will vaccines be available for children?

So far, no coronavirus vaccine has been approved for children. New vaccines are typically tested on adults before researchers launch trials on children, and coronavirus vaccine developers are following this protocol. In September, Pfizer and BioNTech began studying their vaccine on children as young as 12. Moderna followed suit in December. If these trials yield good results, the companies will recruit younger children. The FDA will then have to review these results before the vaccines can get emergency authorization.

Why weren’t children

included in the early studies?

Vaccines are typically tested on adults first in the interest of safety.

What if I forget to take the second dose on time?

Both the vaccines from Pfizer-BioNTech and from Moderna have two doses, with the booster shot coming a few weeks after the first. Pfizer-BioNTech’s second dose comes three weeks after the first, and Moderna’s comes four weeks later. The second dose provides a potent boost that gives people strong, long-lasting immunity.

If for some reason you fail to get the second shot precisely three weeks after the first, you don’t have to start all over again with another two-dose regimen. “The second dose can be picked up at any time after the first. No need to start the series over,” said Dr. Paul Offit, a professor at the University of Pennsylvania and a member of the F.D.A.’s vaccine advisory panel.

And while the two leading vaccines include a second dose, some future vaccine candidates may only require one dose. Johnson & Johnson, for example, is expecting data in January that will show whether its experimental vaccine works after a single dose.

Will my employer require vaccinations?

Employers do have the right to compel their workers to be vaccinated once a vaccine is formally approved. Many hospital systems, for example, require annual flu shots. But employees can seek exemptions based on medical reasons or religious beliefs. In such cases, employers are supposed to provide a “reasonable accommodation” — with a coronavirus vaccine, for example, a worker might be allowed to work if they wear a mask, or to work from home.

How will we know when things are getting better?

The test positivity rate in your community will be an indicator of how things are going. This number is the percentage of overall tests given in a community that come back positive. The lower the number, the fewer new cases and the less likely you are to cross paths with someone who has the virus. “The best number is zero,” Dr. Fauci said. “It’s never going to be zero, but anywhere close to that is great.”

When can we start safely doing normal things, like going to the movies or the theater?

Public health officials estimate that 70 to 75% of the population needs to be vaccinated before people can start moving freely in society again. If things go well, life could get a lot better by late spring and early summer. “It depends on the uptake of the vaccine and the level of infection in the community,” Dr. Fauci said.

Given the surveys so far showing significant public reluctance to get vaccinated, however, it may take awhile to see widespread community protection, he said: “If it turns out that only 50% get vaccinated, then it’s going to take much, much longer to get back to the kind of normality that we’d like to see.”