COVID-19 vaccine: Myths vs. facts

Updated Jan. 25, 2022

Myths about the COVID-19 vaccine have been circulating on social media. UC Davis Health experts dispel myths and give you the facts about the COVID-19 vaccine.

Learn how to schedule your COVID-19 vaccine and get more answers to your vaccine questions

  • UC Davis Health nurse getting COVID-19 vaccine

    Fact: COVID-19 vaccines are safe.

    All three vaccines – Moderna, Pfizer, and Johnson & Johnson (Janssen) – have been very well studied and underwent full reviews by experts. The results were carefully reviewed, and the vaccines were scientifically proven to be very safe.

    The U.S. Food and Drug Administration (FDA) and other experts reviewed data from the clinical trials quicker than normal by looking at data as it came in. In most cases, they wait until the trials are complete. They used the same safety and efficacy standards as always. No safety protocols were changed or skipped.

  • Woman being vaccinated for COVID-19

    Fact: COVID-19 vaccines will not give you coronavirus.

    There's no way to get COVID-19 from the vaccine. None of the FDA-authorized vaccines development in the U.S. use a live virus.

    The Pfizer and Moderna vaccines use messenger ribonucleic acid (mRNA), which carry instructions to your body about how to build a protein. In this case, it’s telling your body to make the spike protein that’s on the novel coronavirus. As a result, your immune system remembers the protein and is ready to attack and eliminate the real SARS-CoV-2 virus.

    The single-dose Johnson & Johnson vaccine is a DNA vaccine. It delivers the same product in the end as the mRNA vaccine produced by Pfizer and Moderna. This new DNA vaccine allows the body to have an immune response against the spike protein, and ultimately, an immune response to infection.

  • test tube showing positive for COVID-19

    Fact: You cannot test positive because of the COVID-19 vaccine.

    There's no part of the coronavirus in the Pfizer, Moderna, or Johnson & Johnson vaccines. Therefore, you can't test positive on a PCR or antigen test. You will, however, test positive for COVID-19 antibodies because your body will have built them up as part of your immune response.

  • research using test tubes

    Myth: COVID-19 vaccines were developed too quickly.

    The COVID-19 vaccines were made at record speed, thanks to the worldwide effort. Along with the constant review by regulatory experts which sped up the process, there were two other reasons for the speed. The first was urgency. COVID-19 vaccine manufacturers and the scientific community dropped everything to develop a vaccine.

    The second reason for a speedier process was that the innovative mRNA approach was already in development. Researchers already created a process for getting the mRNA into the body as part of trials for cancer efforts and other vaccines. What they needed to learn was the genomic sequence of the novel coronavirus.

  • woman sitting with a coffee cup

    Fact: 1 or 2 days of side effects after the COVID-19 vaccine means it's working.

    Some inflammation or soreness at the injection site, as well as minor side effects after getting a COVID-19 vaccine is normal. Everyone will have a slightly different reaction. Chills, fatigue or body aches for a day or two are signs that your body is building its immune response to COVID-19.

  • baby being held

    Fact: COVID-19 vaccines do not cause infertility.

    There's no evidence that COVID-19 vaccines have any effect on fertility. The Vaccines and Related Biological Products Advisory Committee (VRPAC) briefing for both Pfizer and Moderna detail the findings from the clinical trials about effectiveness, safety and side effects. There are no reports of any impact on fertility. You can read the 50-plus page briefings from VRBPAC to the FDA.

    Read more on COVID-19 vaccines and women's health

  • nurse at patient bedside in full PPE

    Fact: Omicron variant symptoms are the same as the original COVID-19 virus.

    The symptoms of the omicron variant appear to be the same as the original version of COVID-19. This strain appears to be more contagious than the original variant, but people are typically getting less sick. It's less likely to cause severe disease such as pneumonia that may require treatment in the hospital.

    Symptoms include cough, fever, and fatigue. There is some evidence that fewer people with omicron lose their taste and smell. 

    Read more about the omicron variant and its symptoms

  • man getting COVID-19 vaccine

    Myth: COVID-19 cases in vaccinated people mean vaccines don't work.

    COVID-19 cases in vaccinated people – known as breakthrough cases – will happen. However, symptoms in vaccinated people are much more minor than those who are unvaccinated. Additionally, people who got the COVID-19 vaccine are less likely to be hospitalized or die, as compared with those who have not been vaccinated.

  • UC Davis Health employee getting COVID-19 vaccine

    Myth: Natural immunity is safer than immunity from a COVID-19 vaccine.

    For many diseases, immunity acquired naturally often lasts longer than immunity from a vaccine. But that means you have to suffer – and survive – the disease.

    With COVID-19, the natural immune response after a mild case appears to be short lived and is much shorter than what's expected from the COVID-19 vaccine. If we were to wait until we reach natural immunity, society would be shut down much longer.

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