8 Things to Know Before Your Second COVID-19 Vaccine

2. You should avoid taking pain relievers before your shot

If you've been hearing stories about second-dose side effects, you may be tempted to take a pain reliever before your appointment.

That's not a good idea, according to the U.S. Centers for Disease Control and Prevention (CDC), unless you've been advised to do so by your doctor. Pain relievers taken preemptively ahead of a shot could dampen the effectiveness of the vaccine, Poland and Schaffner say.

However, it's OK to take acetaminophen (Tylenol) or a nonsteroidal anti-inflammatory drug like Advil or Motrin after your vaccine to treat side effects such as pain, fever, chills or headache.

3. The timing between doses doesn't need to be exact

The second dose of the Pfizer shot is supposed to be given 21 days after the first; for Moderna, the recommended interval between doses is 28 days.

However, if you can't get an appointment on the exact day — or if you have to miss your scheduled appointment for some reason — the CDC does allow some wiggle room. Although the agency recommends trying to stick to the suggested interval, it says the second dose can be given up to six weeks after the first.

If your appointment is scheduled earlier than the recommended date, ask for a later appointment, Schaffner advises. “Your immune response will work perfectly well if you take more time,” he says. “But if you do it too early, the second dose may not invoke an optimal response.”

4. Your second dose should be from the same manufacturer as your first

Doctors are already hearing from patients asking if they can get their second dose from a different manufacturer, often because they realize the other type of vaccine is offered at a location that's more convenient. But the CDC recommends against it: The Moderna and Pfizer vaccines “are not interchangeable with each other or with other COVID-19 vaccine products,” the CDC says. “The safety and efficacy of a mixed-product series have not been evaluated.”

The CDC does allow the mixing of Pfizer and Moderna shots in “exceptional situations,” such as when the vaccine used for someone's first dose is no longer available due to a supply shortage, or if it's unclear which vaccine they got for their first dose.

5. A rash at the injection site isn't a reason to skip your second dose

If you experienced a rash at the injection site three to 10 days after getting your first shot, that doesn't preclude you from getting your second shot, the CDC says, although it recommends getting it in the other arm.

A small number of people have developed such rashes, sometimes called “COVID arm,” after vaccination. Doctors say it's likely a mild allergic reaction that can be treated with an over-the-counter antihistamine such as Benadryl.

In guidance released Feb. 10, the CDC says the reaction is not believed to represent a risk for a more severe allergic reaction when you get your second dose.

6. You should temporarily avoid all other vaccines

It might be time for your shingles or Tdap vaccine, but you should hold off if you are between COVID-19 vaccine doses. Because there's no data on the safety and efficacy of COVID vaccines administered at the same time as other vaccines, the CDC recommends avoiding other immunizations in the two weeks before and after both doses. Holding off also helps prevent confusion about the cause of a reaction if you experience one.

The CDC does allow exceptions in circumstances where avoiding the vaccine would put you at risk, such as a tetanus shot after a wound or a hepatitis shot during an outbreak.

7. Full immunity is not immediate

It takes two weeks after your second dose for your body to build full protection to the virus. After that, you should have almost zero chance of developing severe disease if you are exposed to someone with COVID-19, Schaffner says. The CDC also says you no longer have to quarantine if you're exposed to someone with COVID-19 — as long as you meet these criteria: you don't have symptoms and it hasn't been more than three months since your second vaccine dose.

One possible exception is immunocompromised people, Schaffner says. They will get some level of immunity, he says, “but they may not reach the 95 percent because their immune system is already somewhat compromised, no matter how strong these vaccines are.”

8. You still need to wear a mask

Experts are divided about whether it's OK to hug your grandchild or gather socially with other vaccinated people after you're fully immunized.

But they agree you should continue to wear a mask and practice social distancing in public. For one thing, there's a small chance you could get sick even after you've been vaccinated.

In addition, it's possible that you could still carry the virus and silently transmit it to others who haven't been vaccinated, even if you don't develop symptoms.

And there's one more reason. Until the country reaches herd immunity — the point when a significant portion of the population becomes immune to a disease — it's important for everyone to wear a mask to stop the spread of the virus, Schaffner says. “If we have some people walking around maskless and others not, people left and right are just going to discard their masks,” he says. “We are not ready yet for that for society. Let's all stick to masks a little longer until we get the all clear.”

Michelle Crouch is a contributing writer who has covered health and personal finance for some of the nation's top consumer publications. Her work has appeared in Reader's Digest, Real Simple, Prevention, The Washington Post and The New York Times.