5 Things You Should Know about COVID-19 Vaccines

October 13, 2023, 2:00 PM EDT

What to know

Getting vaccinated builds protection against COVID-19, protecting people from the potentially serious consequences of getting the disease, including hospitalization and death.

Teenage girl with bandaid on arm talking with doctor who is wearing a mask


What CDC knows

COVID-19 vaccines save lives and help keep you out of the hospital. Vaccines are not always effective at preventing infection, but there is extensive data showing that these vaccines prevent severe illness and protect the public’s health.

What CDC is doing

CDC is continually assessing how effective COVID-19 vaccines are against this disease. Intensive safety monitoring has been conducted since the first COVID-19 vaccines came out in 2020 and is ongoing.

1. Updated 2023-2024 COVID-19 vaccines save lives and prevent hospitalizations.

In the first ten months that COVID-19 vaccines were available, they saved over 200,000 lives and prevented over 1.5 million hospitalizations in the United States. This is the purpose of these vaccines: to save lives and prevent severe disease. They can also reduce the risk of Long COVID.

The virus is constantly changing, and our immunity, whether from vaccines or previous infections, fades. Getting updated vaccines like the updated COVID-19 vaccines that are available now continues to be important, especially for older people and those with certain medical conditions. People who fall into these categories should also practice other preventive measures and should seek treatment if they get COVID-19. It is also important to know that healthy children and adults can experience severe disease from COVID-19, so they should stay up to date with the vaccine, as well.

Getting vaccinated builds protection against COVID-19, protecting people from the potentially serious consequences of getting the disease, including hospitalization and death.

2. COVID-19 vaccines are effective.

We have multiple years of experience showing the effectiveness of COVID-19 vaccines. However, the strains of virus causing most of the disease change and immunity wanes over time. The changes from last year's vaccines are small, but they help make the vaccine better at targeting the virus strains circulating now and give your immune system a boost.

To put a finer point on it, the Food and Drug Administration (FDA), the agency that authorizes or approves vaccines, considers the 2023-2024 vaccine update to be a minor change that does not require new clinical trials. This is consistent with how FDA handles annual influenza vaccine strain updates.

Based on three years of experience with these vaccines, we can expect the vaccines to increase protection and save lives.

Evidence supports the benefits of this year's updated COVID-19 vaccines:

  • People vaccinated with Moderna's updated COVID-19 vaccine showed a strong immune response against common variants.
  • In laboratory studies, Novavax's and Pfizer's updated COVID-19 vaccine also produced strong immune responses, which brings better protection against severe illness, hospitalization, and death.

There are many studies that continue to try to assess how well vaccines work in practice. Real-world vaccine effectiveness studies need to be conducted carefully and interpreted with the understanding that there are many factors that can affect results, like how recently someone was infected or how long it has been since they were vaccinated. When considering vaccine effectiveness studies, it is critical to evaluate the totality of evidence across many studies which shows that:

  • COVID-19 vaccines provide sustained protection against severe disease and death, the purpose of the vaccine.
  • The protection against infection tends to be modest and sometimes short-lived, but the vaccines are very effective at protecting against severe illness.

Immune protection from both vaccines and previous infections can decline over time and as new variants emerge. It is important to stay up to date with recommended COVID-19 vaccines, especially for people at higher risk of severe disease, such as older adults and people with medical conditions.

3. When side effects from COVID-19 vaccines occur, they are usually mild or moderate.

COVID-19 vaccines have undergone—and continue to undergo—the most intense vaccine safety monitoring in U.S. history.

The reactions that can happen after COVID-19 vaccines are typically mild to moderate and are similar to those that can occur after other vaccines, such as pain at the injection site or fatigue. These reactions usually go away within a few days. Swelling of the lymph nodes (lymphadenopathy) has been observed after COVID-19 vaccines. As with any medicine or vaccine, there is a rare risk of severe allergic reaction, including anaphylaxis, after COVID-19 vaccines.

There is a rare risk of inflammation of the heart or its surrounding tissue (myocarditis or pericarditis) after COVID-19 vaccines, often in adolescent and young adult males. However, importantly, in one study, the risk of cardiac complications in males 12-17 years old was 1.8 – 5.6 times higher after getting COVID-19 disease than after receiving an mRNA COVID-19 vaccine.

Most people who were reported to have myocarditis after mRNA COVID-19 vaccination responded well to medicine and rest and had resolution of symptoms by the time they went home from the hospital. A study found that most patients with myocarditis after mRNA COVID-19 vaccination were considered to have recovered by their healthcare provider after at least 90 days since onset.

It is important to look at the whole picture in the context of the benefit-risk balance, and the evidence strongly supports that the benefits of COVID-19 vaccines outweigh the risks.

4. Talk to your healthcare provider before you believe everything you see or hear from others.

A single scientific finding is not conclusive and can be used out of context, or there may be other inaccurate information circulating about COVID-19 vaccines.

COVID-19 vaccines do not make you magnetic. They do not alter your DNA. They do not contain microchips to track your movements. The reality is that COVID-19 vaccines are safe and effective. They save lives.

If you have questions or concerns about the COVID-19 vaccine, talk to your healthcare provider.

5. The updated COVID-19 vaccine recommendations are based on data and science.

The available evidence includes extensive safety and effectiveness data on the original and bivalent COVID-19 vaccines and data on the updated vaccines from the three manufacturers, including clinical trial data from Moderna and pre-clinical data from Novavax and Pfizer. On September 12, the Advisory Committee on Immunization Practices (ACIP) recommended the use of the updated 2023-2024 vaccines in everyone 6 months and older after lengthy discussion and public comment. A recently published MMWR summarizes these considerations.

Bottom line: CDC recommends everyone 6 months and older get an updated COVID-19 vaccine to protect against potentially serious COVID-19 outcomes this fall and winter. This is especially important for older adults and people with weakened immune systems, who are at highest risk for severe illness.