February 4, 2021 10:56 AM EST

The big question of the past year was when COVID-19 vaccines would become available. Now, the shots are finally here in the U.S.—albeit not without some significant distribution issues—and making it into more arms each day as state eligibility requirements expand to include groups like elderly adults, first responders, restaurant employees and teachers, in addition to health care workers and nursing home residents.

So, for many, the question is now what to expect after getting vaccinated. Here’s what to know.

What will the side effects be like?

So far, there are two COVID-19 vaccines authorized for use in the U.S., one made by Pfizer-BioNTech and one made by Moderna. They share many of the same common side effects, including swelling and/or redness at the injection site, fatigue, headache, muscle pain, chills, joint pain and fever. Some people won’t experience anything worse than a sore arm, and for most people who do have side effects, they are fairly mild. But some people have reported feeling pretty lousy—almost as if they had the flu for a day or two.

Side effects tend to be worse after the second dose than the first, so you may want to plan to take a day off from work or school after getting your second shot. According to U.S. Centers for Disease Control and Prevention (CDC) data from January, after the second dose of the Pfizer-BioNTech shot, about 75% of people experienced pain, half experienced fatigue and about 42% experienced headache or muscle aches. Chills, fever, swelling, joint pain and nausea were less common. (The report didn’t include data about the second Moderna dose, but reactions are likely to be similar.)

Neither Pfizer-BioNTech nor Moderna’s shot contains live virus, so the vaccines do not actually infect you with COVID-19; the side effects are a sign that your immune system is responding to the vaccine, says Angela Shen, a visiting scientist at Children’s Hospital of Philadelphia’s Vaccine Education Center. (But don’t worry: if you don’t get side effects, that doesn’t mean your vaccine isn’t working.)

To relieve side effects, Shen recommends applying a wet washcloth to the injection site, drinking plenty of fluids and wearing loose clothing. You can take over-the-counter pain medication if you must, but it’s better not to, Shen says. (More on that below.)

Should I avoid painkillers before getting vaccinated?

To play it safe, don’t premedicate. Some studies, both on the virus that causes COVID-19 and other viruses, have suggested that painkillers like ibuprofen (Advil) may interfere with the body’s ability to mount an immune response against the pathogens. For that reason, Shen recommends skipping painkillers prior to vaccination, unless you need them to manage another medical condition. It’s not such a big deal to pop one after your shot, but if your side effects are mild enough that you don’t need to, err on the side of avoidance, she says.

How long will I need to be monitored for an allergic reaction?

Very few people have experienced allergic reactions after receiving COVID-19 vaccines—about 11 people per million doses of the Pfizer-BioNTech shot and about 2.5 people per million doses of the Moderna shot, according to CDC data. Most of those people had previously experienced severe allergic reactions. Most showed signs of anaphylaxis within 15 minutes of getting the vaccine, so the threat seems to be mainly a short-term one.

Most vaccine sites have designated monitoring areas to watch for allergic reactions. If you have a history of allergic reactions, Shen recommends staying for 30 minutes, as opposed to the standard 15. After that, you’re probably out of the woods—but if you do experience a reaction later, be sure to report it to your doctor and seek medical care if necessary.

Can I drink alcohol after getting vaccinated?

Some European health experts have recommended that people avoid drinking a few days before and after their shots, apparently to avoid taxing the immune system. It’s true that alcohol use can suppress immune function over time, but neither the CDC nor Pfizer-BioNTech and Moderna specifically advise people against drinking around the time of vaccination. Clinical trial participants were also not asked to avoid alcohol during testing for either vaccine.

“There’s no evidence to say you should abstain,” Shen says, but it’s not a bad idea to do so anyway as a precautionary measure. There are plenty of reasons not to drink alcohol, and it can be helpful to give your body time to adjust after getting a vaccine, she says.

When am I fully protected?

Your first vaccine dose does offer some protection against getting sick with COVID-19, but you are not fully protected until you’ve had both shots. Even then, the CDC says, it can take “a few weeks” for the body to build up immunity after vaccination.

What will be safe after I get vaccinated?

Pfizer-BioNTech and Moderna’s shots are both about 95% effective at preventing COVID-19 disease, enough that you can be very confident you will not get a symptomatic case of COVID-19 after receiving them.

What remains to be seen is whether a vaccinated person can still become infected with the virus (without developing symptoms) and then spread it to others and, if so, how likely they are to do so. Promising preliminary evidence suggests the shots made by Pfizer-BioNTech, Moderna and AstraZeneca-Oxford (the last of which is not yet authorized in the U.S.) all reduce transmission somewhat—the question is by how much? That’s why experts are urging people to continue wearing masks and social distancing even after getting vaccinated.

That’s also why there’s no easy answer as to what will be safe after you get vaccinated. While you, personally, would likely be protected from COVID-19 if you took a trip or went to the movies, it’s not yet clear whether you could be unknowingly contributing to community spread.

After you’ve been fully vaccinated, it will be much safer to gather in a private home—even indoors and unmasked—as long as the people you’re visiting are also fully vaccinated and do not have frequent contact with unvaccinated or high-risk people. In public places or around unvaccinated people, though, you’ll have to continue wearing a mask and social distancing for the time being, even if you’ve had your shots.

Will I need a booster shot in the future?

It’s possible, but doctors don’t know for sure how long immunity will last. Last month, Moderna’s CEO estimated his company’s shot may confer immunity for a couple years, so it’s reasonable to assume you’d need a booster in a few years’ time, if COVID-19 is still circulating at that point.

Viral variants may also necessitate booster shots. So far, existing COVID-19 vaccines have proven effective against new variants that have emerged as the virus mutates, but over time, it may mutate enough that scientists have to tweak the shots. Fortunately, both Pfizer-BioNTech and Moderna have said it would only take about six weeks to create new shots that incorporate the variants’ unique genetic material.

Write to Jamie Ducharme at jamie.ducharme@time.com.

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