Find answers to frequently asked questions about the COVID-19 vaccines. Please check back often as information may change quickly.


COVID-19 Vaccines: Now available to eligible individuals as supplies allow. Learn more.


Frequently Asked Questions

Getting Vaccinated

Is your hospital providing COVID-19 vaccines and boosters?

Yes, Loma Linda University Health is providing vaccinations based on national, state and county vaccine distribution guidelines. Vaccines (including boosters and third dose shots) are available for eligible individuals as supplies allow — please view our vaccine page to learn more.

Which vaccine should I get for my booster shot?

A booster shot of the Pfizer-BioNTech or Moderna is preferred for everyone 12 years and older. For some adults (like those who have an allergic reaction to these vaccines), the J&J booster shot is recommended. Children aged 12-17 are only eligible to receive the Pfizer-BioNTech booster.

Learn more about booster shot recommendations on the CDC's website.

Do I have to get more than one dose of the vaccine?

When you first get vaccinated, you may need up to two doses depending on which vaccine you receive:

  • If you get the Pfizer/BioNTech vaccine, you'll need your second shot from 21 days to six weeks later.
  • If you get the Moderna vaccine, you'll need your second shot from 28 days to six weeks later.
  • The Johnson & Johnson (J&J) vaccine requires only one dose.

A vaccine booster shot is only one dose. A booster shot of the Pfizer/BioNTech or Moderna is preferred for everyone 12 years and older. Learn more about booster shot recommendations on the CDC's website.

What are the side effects and should I be worried if I have any?

Most people will have soreness around the vaccine injection site. While this can be quite painful, it should start to go away after about 24 hours. If you notice more pain or redness after 24 hours, contact your primary care physician.

Other common side effects include fatigue, muscle pain and headaches. These often show up within a few hours of getting the vaccine and can last for a few days. If these or any other side effects concern you or last longer than a few days, contact your primary care physician. According to the CDC, side effects are more common after the second dose. A small number of people have severe side effects that disrupt daily activities.

If you have any reaction after getting vaccinated, we recommend downloading the CDC’s v-safe app on your smartphone and reporting your symptoms. The CDC launched v-safe to help health experts monitor vaccine safety and respond to potential problems. V-safe will also remind you if you need a second dose of a vaccine.

Do the vaccines have risks?

The COVID-19 vaccines are safe for most people. However, very rare, serious risks have been identified:

Women age 18-49: There may be a link between the Johnson & Johnson (J&J) vaccine and the development of blood clots with low platelets (thrombosis with thrombocytopenia syndrome, or TTS). This condition occurs in about 7 per 1 million women in this age group — it's even more rare for women outside this age group and men of any age. Look out for the following symptoms for three weeks after you get vaccinated, and seek medical care right away if you develop any:

  • Severe or persistent headaches or blurred vision
  • Shortness of breath
  • Chest pain
  • Leg swelling
  • Persistent abdominal pain
  • Easy bruising or tiny blood spots under the skin beyond the injection site

If I get the vaccine, will it protect me from COVID-19? Will it protect others?

Yes, all three vaccines have been shown to be highly effective at protecting you from hospitalization or death from COVID-19. Most people are also protected from serious illness after getting vaccinated.

  • Pfizer/BioNTech and Moderna vaccines: After receiving your second dose, it takes your body about 10-14 days to develop immunity.
  • Johnson & Johnson vaccine:  After receiving the single dose, it takes your body about one month to develop immunity.

You may still be able to transmit COVID-19 to other people even after you've developed immunity. It’s still important to use a mask and practice social distancing after vaccination.

Who Should Get Vaccinated

Should I get the vaccine if I already had COVID-19?

Yes. It’s not yet understood how long your body’s natural immunity to COVID-19 lasts after fighting off the disease.

According to the CDC, you should wait 90 days to get a COVID-19 vaccine if you were treated with monoclonal antibodies or convalescent plasma. If you’re unsure if you received these treatments, talk to your doctor before getting vaccinated.

If I have allergies, should I get a COVID-19 vaccine?

Before you get a COVID-19 vaccine, talk to your doctor if you have had a severe allergic reaction or immediate allergic reaction to other vaccines or injections.

If you aren’t able to get one type of vaccine because you’re allergic to an ingredient in that vaccine, ask your doctor if you should get a different type of vaccine.

The following recommendations are taken from the CDC's COVID-19 vaccine allergy page.

You should not get one of the available mRNA COVID-19 vaccines (Pfizer-BioNTech and Moderna) if:

  • You had a severe allergic reaction to the first dose of that vaccine or any of its ingredients
  • You had any allergic reaction (such as hives, swelling or wheezing) to the first dose of that vaccine or any of its ingredients within four hours
  • You have had a severe allergic reaction or an immediate allergic reaction to any ingredient in these vaccines
  • You’re allergic to polyethylene glycol (PEG)

You should not get the Johnson & Johnson COVID-19 vaccine if:

  • You have had a severe allergic reaction or an immediate allergic reaction to any ingredient in this vaccine
  • You're allergic to polysorbate

You can still get vaccinated if you have:

  • A history of severe allergic reactions not related to vaccines or injections
  • A history of allergies to oral medications
  • Family history of severe allergic reactions

 If you have any other specific concerns not covered above, please talk to your doctor before vaccination.

Should I get the vaccine if I’m immunocompromised or have HIV?

Little is known about the safety of the leading vaccines for people who have compromised immune systems or HIV. You may wish to receive the vaccine to prevent serious illness and should discuss your situation with a healthcare provider. If you choose to get vaccinated, you should continue to wear a mask, wash your hands frequently, and use other COVID-19 precautions.

Can pregnant women get vaccinated?

While safety of all medications and vaccines in pregnancy continues to be studied, medical experts from around the U.S. believe the COVID-19 vaccine is safe to receive during pregnancy. Learn more about vaccines and pregnancy.

Is the COVID-19 vaccine safe for kids?

Clinical trials with thousands of children have shown the Pfizer-BioNTech COVID-19 vaccine is safe for kids ages five to 17. Kids 11 and younger receive a smaller dose using a smaller needle designed for children. All kids need two doses of the vaccine, and it’s important to remember the second dose is safe even if your child has common side effects. Serious side effects from any dose are extremely rare.

Learn more about COVID-19 vaccines and kids.

About the Vaccines

How long will the vaccine protect me?

Right now, we can’t know if a coronavirus vaccine will be permanent or temporary. There simply hasn’t been enough time to test immunity over long periods of time. It is possible that regular booster shots will be necessary.

Are the COVID-19 vaccines tested enough to be safe?

Any vaccine goes through extremely rigorous testing both before and after it is offered to the public. Phase 3 trials (the final stage of testing) include tens of thousands of volunteers, half of which receive a vaccine. Most vaccine side effects are seen within the first six weeks after administration, therefore it is an encouraging sign that no major concerns have been noted following the end of enrollment in these large studies.

Safety has remained a priority even with the quick production of the coronavirus vaccines. Two factors that have sped up vaccine development include large amounts of government funding and ability to rapidly test volunteers during the pandemic.

The full range of side effects may take several years to discover. However, an approved vaccine will have a very small chance of serious side effects. COVID-19 infection presents much higher risk of serious complications.

What's in the coronavirus vaccines?

The Pfizer/BioNtech and Moderna vaccines use messenger RNA (mRNA) to teach your body to fight off COVID-19. The mRNA contains instructions to make a harmless piece of the "spike protein," which the coronavirus uses to attack the body. The vaccine does not contain live coronavirus and it can't alter your DNA.

The Johnson & Johnson vaccine accomplishes the same thing through a different method. Instead of using mRNA, it uses a modified, harmless version of a different virus.

Many vaccines also include substances that protect the vaccine from contamination, keep the vaccine working longer or were used to make the vaccine. None of these substances have ingredients in any amount that can be harmful to humans. The Pfizer/BioNtech, Moderna and Johnson & Johnson vaccines do not contain ethylmercury, formaldehyde or aluminum. No preservatives are used in these vaccines.

Do the vaccines work on COVID-19 variants?

Early data show the vaccines may work against some variants but could be less effective against others.

Vaccine Myths

Can the vaccines infect me with COVID-19?

No. According to the CDC, none of the authorized and recommended COVID-19 vaccines or those in development in the U.S. contain the live virus. That means a vaccine can’t make you sick with COVID-19.

As the vaccine teaches your body how to recognize and fight the virus, you may experience symptoms like fever and fatigue. These don’t mean you have COVID-19 — they’re a normal part of vaccination (though some people don’t experience any side effects).

You may still contract COVID-19 after vaccination for two reasons:

  • Your body needs up to several weeks to gain immunity from the vaccine. During this time, you’re still vulnerable to infection.
  • The vaccines are not 100% effective — immunity is very likely but not guaranteed.

Can the vaccines alter my DNA?

No. The COVID-19 vaccines never interact with DNA in any way.

Will the vaccines make me infertile?

According to the CDC, there is no evidence to suggest COVID-19 vaccines (or any vaccine) damage fertility in the short or long term. Experts believe any future risk is unlikely and scientists will continue to monitor and report vaccine side effects. It’s safe to get vaccinated no matter when you plan to become pregnant.

Recently, there have been unsubstantiated claims on social media that the COVID-19 vaccines can affect the development of the placenta. These claims have already been debunked by women’s health experts.