It can be hard to know who needs to get a COVID-19 booster and why. The Morehouse School of Medicine National COVID-19 Resiliency Network created a fact sheet to help people understand the updated COVID-19 boosters, why they keep our communities healthy, and who is eligible to get one.

A COVID-19 vaccine might: Protect you from getting COVID-19 Prevent you from becoming seriously ill, becoming hospitalized or dying due to COVID-19 Limit the spread of COVID-19

Getting COVID-19 offers some natural protection or immunity from reinfection with the virus that causes COVID-19. It's estimated that getting COVID-19 and COVID-19 vaccination both result in a low risk of another infection with a similar variant for at least six months. But because reinfection is possible and COVID-19 can cause severe medical complications, it's recommended that people who have already had COVID-19 get a COVID-19 vaccine. The spread of new variants can also increase the risk of reinfection. In addition, COVID-19 vaccination might offer better protection than getting sick with COVID-19. A recent study showed that unvaccinated people who already had COVID-19 are more than twice as likely as fully vaccinated people to be reinfected with COVID-19. If you were treated for COVID-19 with monoclonal antibodies or convalescent plasma, there is no need to delay getting a COVID-19 vaccine.

Because there is an urgent need for COVID-19 vaccines and the Food and Drug Administration's (FDA's) vaccine approval process can take years, the FDA first gave emergency use authorization to COVID-19 vaccines based on less data than is typically required. The data must show that the vaccines are safe and effective before the FDA can give emergency use authorization or approval. Vaccines with FDA emergency use authorization or approval include: Pfizer-BioNTech COVID-19 vaccine. The FDA has approved the Pfizer-BioNTech COVID-19 vaccine, now called Comirnaty, to prevent COVID-19 in people age 12 and older. The FDA approved Comirnaty after data found the vaccine is safe and effective. The Pfizer-BioNTech COVID-19 vaccine is 91% effective in preventing severe illness with COVID-19 in people age 16 and older. The vaccine is 100% effective in preventing COVID-19 in children ages 12 through 15. For people age 12 and older, the Pfizer-BioNTech COVID-19 vaccine involves two shots. The second dose can be given three to eight weeks after the first dose. The vaccine is available under an emergency use authorization for children ages 5 through 11. This vaccine is about 91% effective in preventing COVID-19 in children ages 5 through 11. It requires two shots, given three weeks apart. It also contains a lower amount of mRNA than the Pfizer-BioNTech COVID-19 vaccine used for people age 12 and older. The vaccine is now also available under an emergency use authorization for children ages 6 months through 4 years old. It requires three shots. The first two shots are given three to eight weeks apart. The third shot is given at least eight weeks after the second shot. Moderna COVID-19 vaccine. The FDA has approved the Moderna COVID-19 vaccine, now called Spikevax, to prevent COVID-19 in people age 18 and older. The Moderna COVID-19 vaccine is 94% effective in preventing COVID-19 with symptoms. It requires two shots. The second dose can be given four to eight weeks after the first dose. The vaccine is now also available under an emergency use authorization for children ages 6 months through 17 years old. It requires two shots, given four to eight weeks apart. Janssen/Johnson & Johnson COVID-19 vaccine. This vaccine is available under an emergency use authorization. In clinical trials, this vaccine was 66% effective in preventing the COVID-19 virus with symptoms — as of 14 days after vaccination. The vaccine also was 85% effective at preventing severe disease with COVID-19 — at least 28 days after vaccination. It requires one shot. Due to the risk of a potentially life-threatening blood-clotting problem, the FDA is restricting use of the Janssen/Johnson & Johnson vaccine to certain people age 18 and older. Examples include people who had a severe allergic reaction after getting an mRNA COVID-19 vaccine and people who can't get an mRNA COVID-19 vaccine due to limited access or personal or religious concerns. If you get this vaccine, be sure to understand the risks and symptoms of the blood-clotting problem. Novavax COVID-19 vaccine, adjuvanted. This vaccine is available under an emergency use authorization for people age 12 and older. It requires two shots, given three to eight weeks apart. Research done before the spread of the delta and omicron variants has shown that the vaccine is 90% effective at preventing mild, moderate and severe disease with COVID-19. For people age 65 and older, the vaccine is 79% effective. The shortest interval between the first and second doses of mRNA COVID-19 vaccines is still recommended for people who have weakened immune systems, people age 65 and older and others who need rapid protection due to concern about community transmission or risk of severe illness. An eight-week interval between the first and second doses might be best for some people, especially males ages 12 to 39. A longer interval might increase protection against COVID-19 and reduce the risk of rare heart problems, such as myocarditis and pericarditis.

Both the Pfizer-BioNTech and the Moderna COVID-19 vaccines use genetically engineered messenger RNA (mRNA). Coronaviruses have a spikelike structure on their surface called an S protein. COVID-19 mRNA vaccines give your cells instructions for how to make a harmless piece of an S protein. After vaccination, your muscle cells begin making the S protein pieces and displaying them on cell surfaces. The immune system recognizes the protein and begins building an immune response and making antibodies. After delivering instructions, the mRNA is immediately broken down. It never enters the nucleus of your cells, where your DNA is kept. The Janssen/Johnson & Johnson COVID-19 vaccine is a vector vaccine. In this type of vaccine, genetic material from the COVID-19 virus is placed in a different kind of weakened live virus, such as an adenovirus. When the weakened virus (viral vector) gets into your cells, it delivers genetic material from the COVID-19 virus that gives your cells instructions to make copies of the S protein. Once your cells display the S proteins on their surfaces, your immune system responds by creating antibodies and defensive white blood cells. If you become infected with the virus that causes COVID-19, the antibodies will fight the virus. Viral vector COVID-19 vaccines can't cause you to become infected with the COVID-19 virus or the viral vector virus. Also, the genetic material that's delivered doesn't become part of your DNA. The Novavax COVID-19, adjuvanted vaccine is a protein subunit vaccine. These vaccines include only the parts (proteins) of a virus that best stimulate your immune system. The Novavax COVID-19 vaccine contains harmless S proteins. It also has an ingredient called an adjuvant that helps with your immune system response. Once your immune system recognizes the S proteins, this vaccine creates antibodies and defensive white blood cells. If you later become infected with the COVID-19 virus, the antibodies will fight the virus. Protein subunit COVID-19 vaccines don’t use any live virus and can’t cause you to become infected with the COVID-19 virus. The protein pieces also don’t enter the nucleus of your cells, where your DNA is kept.

No. The COVID-19 vaccines currently being developed in the U.S. don't use the live virus that causes COVID-19. As a result, the COVID-19 vaccines can't cause you to become sick with COVID-19 or shed any vaccine parts. It can take a few weeks for your body to build immunity after getting a COVID-19 vaccination. As a result, it's possible that you could become infected with the virus that causes COVID-19 just before or after being vaccinated.

A COVID-19 vaccine can cause mild side effects after the first or second dose, including: Pain, redness or swelling where the shot was given Fever Fatigue Headache Muscle pain Chills Joint pain Nausea and vomiting Feeling unwell Swollen lymph nodes Babies ages 6 months through 3 years old also might cry, feel sleepy or lose their appetite after vaccination. You'll be monitored for 15 minutes after getting a COVID-19 vaccine to see if you have an allergic reaction. Most side effects go away in a few days. Side effects after the second dose might be more intense. Many people have no side effects. Side effects of booster shots appear to be similar to side effects experienced after the two-dose or single-dose primary shots. If the redness or tenderness where the shot was given gets worse after 24 hours or you are concerned about any side effects, contact your doctor.

Because COVID-19 vaccines clinical trials only started in the summer of 2020, it's not yet clear if these vaccines will have long-term side effects. However, vaccines rarely cause long-term side effects. If you're concerned, in the U.S., safety data on COVID-19 vaccines will be reported to a national program called the Vaccine Adverse Event Reporting System. This data is available to the public. The CDC has also created v-safe, a smartphone-based tool that allows users to report COVID-19 vaccine side effects. If you have additional questions or concerns about your symptoms, talk to your doctor.

Yes, COVID-19 vaccines give you protection against serious illness caused by the virus that causes COVID-19. The main variant in the United States is omicron (B.1.1.529). This variant spreads more easily than the original virus that causes COVID-19 and the delta variant. But omicron seems to cause less severe disease. Omicron has a few major offshoots, also called sublineages, branching off from B.1.1.529. Together the omicron variants make up nearly all COVID-19 infections in the United States. This is an estimate from early 2023 based on genetic sequencing of samples from people with COVID-19 infections, according to the CDC. People who are up to date on their vaccines can get breakthrough infections. They can then spread the virus to others. But the COVID-19 vaccines can work to prevent severe illness.