A growing number of North Texans have received at least one dose of the COVID-19 vaccine since the shots were approved, and more residents are becoming eligible for their second doses with each passing week.

The Pfizer-BioNTech and Moderna vaccines were approved and ready for the public with unprecedented speed, and questions remain about the short- and long-term effects of inoculation.

Here’s what people can expect after getting their first and second doses of the vaccines.

Will there be any side effects?

Like most vaccines, the Pfizer and Moderna shots may cause mild side effects, according to the Centers for Disease Control and Prevention.

The most common side effects are pain, swelling and redness in the arm where the dose was received. People also may experience chills, fatigue and headaches.

In clinical trials of both vaccines, mild to moderate side effects within a week of vaccination were common, the CDC says. Most side effects, however, usually occur within a day or two and go away in a few days.

The CDC says side effects throughout the body, which may feel like flu symptoms, were more common after the second dose.

To reduce soreness in the arm where the vaccine was administered, the CDC recommends applying a cold, wet washcloth to the area and using and exercising the arm. Drinking plenty of fluids and wearing lightweight clothing can reduce the discomfort of fever or flu-like symptoms.

If soreness in the arm increases after 24 hours, people should call their health care providers, the CDC says.

What about serious side effects?

The Food and Drug Administration says that there is a “remote” chance of serious side effects with the Moderna and Pfizer vaccines.

Symptoms of a serious allergic reaction include difficulty breathing, swelling of the face and throat, rapid heartbeat, rashes, dizziness and weakness, according to the FDA.

A serious allergic reaction would usually occur within a few minutes to an hour of vaccination, which is why health care providers monitor patients for a few minutes after they receive shots.

Health experts say serious side effects from the vaccine are rare.

Of more than 4 million first doses of the Moderna shot given between Dec. 21 and Jan. 10, only 1,266 serious side effects were reported, or about 0.03% of all people who received a first dose during that time, according to the CDC.

Of more than 1.8 million first doses of the Pfizer shot administered between Dec. 14 and Dec. 23, only 4,393 serious side effects were reported, or about 0.2% of all people who received a first dose during that time, according to the CDC.

The CDC recommends people call their health care providers if they experience any symptoms of a serious allergic reaction, or if their symptoms do not go away on their own after a few days.

Do people have any protection after the first shot?

People will have some protection after their first shot. Preliminary data showed that the Moderna shot was 80.2% effective after one dose, while the Pfizer vaccine was 52.4% effective after the first dose.

However, patients were followed only for a short period, so longer-term immunity after one dose is not known.

When will I be fully protected from COVID-19?

The Moderna and Pfizer vaccines are about 95% effective, health experts say.

But immunity doesn’t happen right away. Vaccines work by teaching the immune system how to respond to a virus, and it takes a while for the body to learn the response.

People have to receive two doses of each vaccine a few weeks apart to build immunity. For the Moderna vaccine, the second dose is administered 28 days after the first. The second dose of the Pfizer vaccine comes 21 days after the first.

It’s important to get the second dose as close to the correct time as possible, but people can still be protected if they get their second dose up to six weeks later with both vaccines, the CDC says.

Health experts say that the time it takes someone to build full immunity after the second shot varies but that it typically happens up to two weeks after vaccination.

Can I still get COVID-19 if I’m fully vaccinated?

It’s possible that someone could test positive for the virus even if they are fully vaccinated, health experts say.

Because the Moderna and Pfizer vaccines are only 95% effective, it’s possible some people could be fully vaccinated and still get infected.

As more people become vaccinated, that will become more unlikely, health experts say.

It’s also possible someone could become infected with the virus before they got their first or second dose and test positive after vaccination.

Can I spread COVID-19 if I’m fully vaccinated?

It’s clear that the COVID-19 vaccines help protect patients against serious illness, health experts say. But researchers are still collecting data on whether someone can spread the virus after being fully vaccinated.

The initial trials of the Moderna and Pfizer vaccines focused on how many people developed symptoms of the virus, but not on how the vaccine protects people with an asymptomatic infection.

That means it’s possible that a vaccinated person could encounter the virus and have enough of it in their body to spread it to others without developing symptoms themselves, health experts say.

How often will I have to get the COVID-19 vaccine?

It’s not known how long immunity lasts after someone is fully vaccinated, according to the CDC. It could end up being a yearly vaccine, like the influenza shot, or it could require a booster dose every few years. More research is needed to know for sure, health experts say.

Do I still have to wear a mask and social distance after I’m fully vaccinated?

Health experts say vaccinated individuals should continue to act as though they are not fully immune.

Because little is known about whether vaccinated people can spread the virus to others and because the vaccine is not 100% effective, it’s important to continue following public health guidelines such as social distancing and mask wearing, health experts say.

It’s also probably going to take some time before enough of the population is vaccinated to achieve herd immunity, a term that means enough people have immunity to significantly decrease the likelihood of infection in a community.

The CDC said it’s not yet known what portion of people need to be vaccinated to achieve herd immunity, as the rate varies by disease.

As long as a large portion of the population isn’t vaccinated, it’s important for people to continue to take steps to protect themselves and others from the virus, health experts say.

Twitter: @catherinemarfin