Vaccine and immunization guidance from Mayo Clinic

Vaccines and other types of immunizations are safe and effective at preventing illness that affects people of every age. They protect you and the people around you. Vaccines help train the immune system to respond to the cause of an illness. Other types of immunizations supply medicine to help the immune system respond. The timing is planned so that vaccines and immunizations against a disease are given before you're likely to be exposed to it.

This guide explains the benefits of vaccines and other types of immunizations. It explains how they're developed and which ones are recommended at different ages.

Vaccines and immunizations protect against getting serious diseases that can harm or kill a baby, child or adult.

They also can lower the risk of developing complications related to diseases. For example, the human papillomavirus (HPV) vaccine prevents some types of cancers caused by HPV.

Vaccines and immunizations also may lower the chance that you or your child will spread a disease. This is important because some people can't get vaccines due to health or age, or don't have a strong immune system reaction to vaccination.

No. It is always better to avoid the risk of harm by getting a vaccine rather than an infection. Vaccination is safer than infection. That is especially true for infections that you can get more than once, such as tetanus.

Some infections caused by bacteria worsen so fast that antibiotic treatment given right away may not prevent harm. Many infections caused by viruses have no treatments. And some may lead to long-term or permanent complications.

Examples of illness that may be serious include:

• Chickenpox infection can lead to ear infection, skin infections, pneumonia and in rare cases, death.
• Polio infection can cause paralysis. Even with recovery, polio can leave long-lasting muscle issues or joint pain that gets worse over time.
• Mumps infection could lead to brain inflammation, deafness, sterility or decreased fertility.
• Haemophilus influenzae type b (Hib) bacterial infection can cause sepsis or meningitis. That could lead to lasting deafness, epilepsy, brain damage or even death.

Vaccines lower the risk of getting a disease by helping the body's immune system see and clear out germs. After vaccination, the immune system responds and remembers how to fight that virus in the future.

Some germs, such as the virus that causes measles, don't change much over time. The immune system's memory protects the body for a long time after vaccination.

Other germs, such as the viruses that cause influenza and coronavirus disease 2019 (COVID-19), change quickly. That means every season the vaccines need an update because past infections don't help the immune system respond as quickly.

People with a weakened immune system may need a different vaccine schedule to make sure the body makes enough protection.

Vaccines go through a strict scientific and regulatory process to make sure they are safe, effective and useful before they are licensed.

Not all diseases can be prevented with vaccines. The disease has to affect enough people to make prevention important. The vaccine has to be proved safe and effective. And a disease qualifies for a vaccine if there are no good alternative ways to prevent it.

Different vaccines help the immune system in different ways. To mimic an infection, a vaccine might use:

• A weakened virus that a working immune system can clear out.
• The part of the germ or a look-alike part that the immune system would respond to during real infection.
• Biologic instructions for how to make a protein from the germ that the body could see and respond to.

Vaccine ideas are tested in a lab using simple models, such as cells. The ones that work in cells are tested in more-complex models. From there, researchers test the most promising vaccines and immunizations with the fewest side effects in human volunteers.

If a vaccine is safe, effective and can be made to quality standards, the vaccine maker can apply to sell the vaccine. Permission to sell vaccines differs by country. But in general, a health agency reviews the research results, the manufacturer's track record and how the vaccine is made before approving it. After approval, the vaccine maker can't change how the vaccine is made or what ingredients are used without having another review process.

After a vaccine is released, health agencies may recommend the groups of people who are most likely to benefit from the vaccine. Health agencies also monitor vaccines for safety and for how well they continue to work. If a virus or bacterium no longer spreads in humans, health agencies also change vaccine recommendations.

During a pandemic, a safe and effective vaccine may have a faster review than is typical. Or a pandemic vaccine may be allowed based on earlier or shorter term data than is usually available, with ongoing tracking and data collection. But no matter how quickly a vaccine is reviewed or how much data is collected, vaccines developed during a pandemic still must show that they are safe and effective.

See Different types of COVID-19 vaccines: How they work

Some vaccines are made with killed germs or part of a germ. Those vaccines can't give you the disease they are meant to prevent.

One type of vaccine uses a weakened virus. These are called attenuated vaccines. These vaccines give you a very limited infection that trains the immune system without causing the disease. A typical immune system can easily handle this type of germ. It is so mild that it is almost impossible to diagnose. It goes away on its own without any treatment. But it is enough to make you immune to the real form of the infection. Live attenuated vaccines aren't given to people who are pregnant or who have immune systems that don't respond quickly or strongly.

Some people think vaccinations make them sick because they have a headache, fever or other symptoms after getting a vaccine. But these symptoms are a sign that the immune system recognizes the germ the vaccine mimics. The immune system causes these symptoms as it prepares to clear out the imitation illness.

Serious health problems from vaccines are very rare.

Vaccines do not cause conditions such as autism or cancer.

Vaccines can protect against cancer or infertility caused by a germ. For example, vaccines against human papillomavirus (HPV) protect against some cancers. The mumps vaccine helps protect against a mumps-related complication that can lower sperm production and fertility in some men.

A few vaccines can have rare side effects. But for some diseases, your chance of these complications is higher after infection than after vaccination. So it is better to get a vaccination than to get an infection.

Allergic reactions after vaccines are rare. When allergic reactions do happen, they often cause hives and itching all over the body.

Rarely, some allergic reactions cause trouble breathing or swallowing, usually in the first minutes after vaccination. These reactions are life-threatening and need treatment right away. These reactions can be treated with medicine.

Vaccines and immunizations are timed based on safety, when you're likely to have the most effective response, and before you're likely to come into contact with the bacteria or viruses. Those factors mean that vaccines and immunizations are recommended at every age, starting at birth.

Vaccines protect babies from germs that can cause serious illness, lasting harm or death.

Most newborns have an immune system that gives some protection against germs. Once children enter the world, some research suggests they can expect to have 6 to 8 infections a year until around age 7.

At first, children may be protected by the vaccinations or disease history of the birth parent. This is why pregnant individuals should get a dose of Tdap vaccine during pregnancy. Babies also benefit if the birth parent gets a COVID-19, RSV or influenza vaccine. But after around age 6 months, babies start to rely on their own immune systems.

Before vaccines, infections such as measles, mumps, chickenpox, diphtheria and whooping cough were common. All together, they killed thousands of children every year in the United States. Widespread vaccination has lowered death rates from many of these diseases by 90% to 100%, making them very rare causes of death.

Vaccines have made many diseases rare. But the viruses and bacteria that can cause outbreaks of these diseases still exist and do spread. Getting these vaccines on schedule keeps vaccine-preventable disease rare.

See Childhood vaccines: Tough questions, straight answers

Babies and children get vaccines and immunizations against common viruses and bacteria that can cause serious illness.

Timing is key. From birth, vaccines are planned when they'll best protect children. That means ideally vaccines are given when the immune system is ready and before a child is expected to come in contact with the real infection.

But the childhood vaccination schedule can be flexible if needed. Some shots may be given early or between regularly scheduled health checkups depending on the season or other circumstances. And in some cases, your child's healthcare professional might suggest a vaccine out of order, such as during a local outbreak or your travel.

Across the world, many schools require that children be vaccinated to attend school or child care. Required vaccines may be different depending on where you live. In the United States, school and child care vaccine requirements are set by state laws, not federal law.

These requirements help lower the spread of preventable illness. Even if some vaccines aren't required for a child to go to school, medical experts still recommend following your local vaccine and immunization schedule. The listed vaccines are safe, effective, needed to prevent illness and don't have reasonable alternatives.

Children who are not up to date on immunization risk getting and spreading infections more easily. That could lead to health complications and missed learning time for a child, as well as missed work for caregivers.

Ask your healthcare professional if your child is up to date on vaccinations.

Talk with your child's healthcare professional if you want to change your child's vaccine schedule. Getting vaccinated on schedule provides strong and timely protection against illness. The vaccines are scheduled to be given when they are needed, when they are safe to receive and when they'll be effective.

Children who get behind in their vaccines have higher rates of vaccine-preventable diseases. They also may struggle to catch up on the vaccines that are due.

Many vaccines can be given even if your child has a mild illness, such as a cold, earache or mild fever.

Talk with your child's healthcare professional regularly to keep your child's vaccination status up to date. If your child falls behind the standard vaccine schedule, ask about catch-up immunizations.

It's not a good idea to skip some vaccines that are due. That leaves your child unprotected from diseases. It raises the risk of getting a vaccine-preventable disease in the future. Skipping a vaccine also raises the risk that a child spreads certain diseases to others.

Health experts review the vaccine schedule regularly. Different countries may have different schedules because health risks are not the same everywhere. Access to healthcare, presence of seasonal diseases and the risk of specific illnesses vary by location.

If you have questions about a certain vaccine, talk with your child's healthcare team.

Vaccines do not cause autism. Vaccines do not make autism worse. The original study that claimed this connection in 1998 was based on falsehoods. That study was removed from the scientific record in 2010.

In the time between when that study was published and when it was pulled, scientists tried but could not find any link between autism and vaccines. Global research examining large groups of people using a range of methods did not provide evidence to support the link.

Scientists do not know exactly what causes autism. But a solid body of research says that vaccines do not cause autism.

Adults need vaccinations because people are exposed to germs at all ages. Some vaccines protect against a disease for a lifetime. But for others, a booster or a new vaccine boosts your protection. For example, chickenpox infection can return as shingles as people age. So getting the shingles vaccine helps prevent that painful illness.

Also, as people age, the immune system doesn't work as well. That raises the risk of serious illness for many diseases. To lower the risk, vaccines are recommended for diseases that adults, often age 50 or older, may get and have trouble getting over quickly.

Depending on your age, health, lifestyle, job, travel, previous vaccinations and sexual habits, vaccines can help prevent serious illness.

See Vaccines for adults: Which do I need?

Vaccines that are made from killed germs or only part of a germ are generally safe during pregnancy. Some are strongly recommended because of pregnancy.

If you're pregnant, vaccines that may be recommended include COVID-19, seasonal influenza, Tdap and RSV. But talk with a healthcare professional about what is safe for you. Vaccines that use a live, weakened virus are not given during pregnancy.

Vaccines recommended during pregnancy help protect the pregnant person, the baby or both. Some vaccines help during pregnancy to protect the pregnant person. Other vaccines help protect babies in the months just after birth.

If you have disease risks due to work, travel, health or habits, your healthcare professional may suggest other vaccines. Examples include hepatitis B, Haemophilus influenzae b, meningococcus and polio vaccines. There may be limited research on use of these vaccines during pregnancy. But if your healthcare professional recommends one, it is often because the benefits outweigh the risks.

Scientific reasoning supports vaccine safety in pregnancy, even when pregnant people aren't included in early clinical trials. Health agencies track vaccine outcomes and can quickly investigate any safety concerns. Health complications, such as early labor, have not been noted among pregnant people who have gotten vaccines made with killed viruses.

See Which vaccines are recommended during pregnancy and which ones should I avoid?

With the exception of the yellow fever vaccine, it is generally considered safe to get vaccines while you are breastfeeding. But talk with a healthcare professional about what is safe for you.

With the yellow fever vaccine, there is a risk of passing the virus to the baby through breastmilk. But if you're traveling to an area where you may get yellow fever, talk to your healthcare professional about going ahead with that vaccine.

No. Data from safety tracking networks or clinical trials has not found harmful effects on fertility or menstruation linked to vaccines.

The body's immune system response to a vaccine can sometimes cause your period to come on earlier or later and be lighter or heavier. If this happens, the changes are often small and only temporary. Research on COVID-19 vaccines in particular finds that if menstrual changes happen, they are usually mild and go back to a typical period over time. Studies on COVID-19 vaccination also show no evidence of a harmful effect on fertility.

Mayo Clinic recommends getting the annual coronavirus disease 2019 (COVID-19) vaccine. It protects against serious illness, the need for hospital care due to COVID-19 and death from COVID-19.

Children and teens

COVID-19 vaccines protect children age 6 months and older. The vaccine helps prevent serious illness, especially in babies younger than age 2 years. It lowers the rare risks of death or multisystem inflammatory syndrome in children (MIS-C). The vaccine also lowers the risk of symptoms that last longer than three months, called long COVID.

Children ages 6 months to 23 months are up to date after two doses of Spikevax, spaced at least four weeks apart. But the number of vaccine doses depends on a few factors. The vaccine type matters, as well as if a child has been vaccinated before and if a child has a weakened immune system.

Adults

Staying up to date on COVID-19 vaccines is most important for people at higher risk. That includes adults age 65 and older, people with weakened immune systems, people who are pregnant, and people with chronic conditions, such as heart disease, lung disease or obesity.

Serious side effects from the COVID-19 vaccine are very rare. Because of that, even healthy adults benefit from the COVID-19 vaccine. Most people are up to date after one dose of the 2025-2026 COVID-19 vaccine from any vaccine maker.

Pregnancy

People who are pregnant and get COVID-19 have a higher risk of severe illness than people who are not pregnant. The risk of needing care in the hospital or help breathing is higher, and the risks to the unborn baby are higher.

Getting COVID-19 while pregnant raises the risk of giving birth early. It also raises the risk of having a child with low birth weight or having a child that needs specialized care. Getting a COVID-19 vaccine during pregnancy may help protect newborns who can't yet be vaccinated.

Safety, side effects and precautions

COVID-19 vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

The flu, also called influenza, is a viral infection. Mayo Clinic recommends an annual flu vaccine to help prevent serious illness and the need for care in the hospital. The vaccine also may lower the risk of death due to the flu. Flu vaccines are updated every year to match the types of flu that are likely to spread during flu season.

Children and teens

The flu vaccine protects people age 6 months and older. In this age group, it protects against serious illness and death, and it lowers the risk of bacterial infections after the flu. As a shot or nasal spray, the flu vaccine is the best bet for avoiding the flu. The first time children between the ages of 6 months and 8 years get the flu vaccine, they may need two doses given at least four weeks apart. After that, they can receive single annual doses of the flu vaccine. Check with your child's healthcare professional. Flu vaccines help a child's immune system quickly respond when flu viruses infect the body. Getting a flu vaccine during pregnancy may help protect the pregnant person and the newborn.

Adults

For adults, the vaccine may be available as a shot, a jet injector or a nasal spray. Your flu shot options may depend on your age and health. Among people age 65 and older, high-dose, adjuvanted and recombinant flu vaccines help prevent hospital stays better than the standard flu vaccines do. Among people who've had a solid organ transplant, these types of flu vaccines may boost the immune system's ability to respond to an infection. But any flu vaccination is better than none. So if you can't get a high-dose, adjuvanted or recombinant flu vaccine, then get the flu vaccine that is available. If you have an egg allergy, you can still get a flu vaccine.

Pregnancy

Getting a flu shot during pregnancy can help protect you and the unborn baby from serious complications from influenza. It also can help protect the baby after birth. Changes in the immune system, heart and lungs make it more likely for people who are pregnant to get seriously ill from the flu. The flu vaccine is updated every year to try to match the flu viruses that are spreading. Flu shots made from killed germs or only part of a germ are safe during pregnancy. Talk with your healthcare professional about which flu vaccine is best for you.

Safety, side effects and precautions

Influenza vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends a hepatitis B vaccine to prevent liver failure or liver cancer caused by the hepatitis B virus. The virus spreads through contact with blood and body fluids as well as through contact with the environment. The virus can persist for a week on surfaces.

Children and teens

The hepatitis B vaccine is given at birth or during childhood in hundreds of countries across the world. It helps prevent inflammation of the liver, called hepatitis, and liver damage called cirrhosis. The vaccine helps prevent liver cancer and the spread of the virus to others.

Giving the vaccine at birth protects children who may be exposed to hepatitis B through casual contact with a person who is infected. If infected with hepatitis B, newborns and children up to age 1 year who are not vaccinated have a 90% to 95% risk of developing chronic hepatitis B. The risk for children ages 1 to 4 years is 25% to 50%. A hepatitis B vaccine may be given alone or with other vaccines. The vaccine series gives lifelong immunity in most cases.

Adults

If you didn't get vaccinated as a baby or child, you should get the vaccine through age 59. If you are age 60 or older and haven't gotten vaccinated, get the vaccine if you're at risk of being exposed to the hepatitis B virus. People age 60 and older who haven't been vaccinated and are not at high risk also can choose to get the vaccine. The vaccine is given as two shots one month apart, or three or four shots over six months. How many shots you get depends on the type of hepatitis B vaccine that you're given. You can't get hepatitis B from the vaccine.

Pregnancy

You may be able to get a hepatitis B vaccine during pregnancy.

Safety, side effects and precautions

Hepatitis B vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends a respiratory syncytial virus (RSV) vaccine for people who plan to give birth during RSV season, for all people 75 years and older, and for people 50 years and older at increased risk for severe disease from RSV. Mayo Clinic recommends RSV immunization for babies to help prevent serious breathing issues.

Children and teens

RSV immunization is a medicine for all babies younger than 8 months old who are going into their first RSV season. It contains ready-made proteins called antibodies. These antibodies act like ones the body would make after a real infection. This helps protect babies who aren't protected by the vaccine to the birth parent during pregnancy. Also, babies 8 months through 19 months who are at high risk of serious illness also may get this medicine.

RSV is a common virus. It is a leading cause of hospital care for babies. RSV immunization helps prevent serious breathing issues that may need to be treated in the hospital.

Adults

To help prevent complications from RSV infection, all people 75 years and older should get the vaccine. Also those 50 years and older who have certain risk factors for severe RSV infection should get the RSV vaccine. If you're age 50 through 74, talk with your healthcare professional about whether you're at higher risk of getting serious RSV. Because older adults have weaker immune systems and often have other conditions, an RSV vaccine helps prevent serious illness. This is especially true for people with heart or lung disease.

Pregnancy

The RSV vaccine also is given to pregnant people during RSV season. It helps protect babies from birth through the first months of life.

Safety, side effects and precautions

The RSV vaccine and immunization have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends getting a pneumococcal conjugate vaccine (PCV) to protect against Streptococcus pneumoniae bacteria that can infect the lungs, blood and brain. The infection can move quickly. It may need to be treated in the hospital and may be deadly.

Children and teens

The PCV vaccines use pieces of the bacteria from 13, 15, 20, 21 or 23 common strains to imitate infection. That allows the body to learn about the bacteria and quickly respond to real infection. The first dose is due at age 2 months. A pneumococcal vaccine may be given to older children and teens at high risk of pneumococcal disease.

The bacteria that cause pneumococcal disease are found naturally in the nose and throat and don't cause illness. But after a viral illness, a child's immune system may not control the bacteria as well. The vaccine speeds up the immune system's ability to quickly respond and prevent bacteria from causing serious illness.

The vaccine helps prevent the lung infection pneumonia. It also helps prevent lung damage from a bacterial infection between the lung and chest wall called empyema. The pneumococcal vaccine helps prevent bloodstream infections. It also helps prevent an infection of the brain and spinal cord called meningitis.

Adults

The pneumococcal vaccine isn't usually recommended to adults younger than age 50 who aren't at high risk of serious illness. For people age 50 and older, one dose of a vaccine is recommended for lifelong protection.

Pregnancy

The pneumococcal vaccine isn't usually recommended to adults younger than age 50 who aren't at high risk of serious illness. If it is recommended for you, the vaccines may be given while you're pregnant.

Safety, side effects and precautions

Pneumococcal vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends the rotavirus vaccine to protect babies from serious illness, the need for care in the hospital and deaths from rotavirus infection. Rotavirus spreads easily and causes an infection in the gut.

Children and teens

The rotavirus vaccine in either two or three doses is often recommended before age 6 months. The vaccine helps prevent fever, vomiting and diarrhea due to rotavirus. It also helps prevent dehydration from rotavirus symptoms. Dehydration can be serious and lead to death.

Safety, side effects and precautions

Rotavirus vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends the diphtheria, tetanus and pertussis vaccine (DTaP, Tdap) to help prevent severe bacterial infections.

Children and teens

DTaP helps prevent diphtheria, tetanus and pertussis, also called whooping cough. The vaccine also helps lower the risk of harms from these diseases.

Harms from diphtheria, tetanus and pertussis include:

• Diphtheria: Trouble breathing, organ damage and nerve damage that can be fatal.
• Tetanus: Muscle spasms that can fracture bones, lung infections, trouble breathing and blood clots that can be fatal.
• Pertussis: Lung and ear infections, breathing trouble, dehydration, seizures, and brain damage.

For babies, the shot is called DTaP. That stands for diphtheria and tetanus toxoids and acellular pertussis. The version given to older children, teens and adults is called Tdap. That stands for tetanus toxoid, reduced diphtheria toxoid and acellular pertussis. Tdap has lower amounts of diphtheria and pertussis toxins than DTaP. DTaP protects children age 2 months and older. A common recommendation worldwide is for babies and children to get four doses of the DTaP vaccine. The doses are given at ages 2 months, 4 months, 6 months, and between 15 and 18 months. After that, a Tdap booster is often recommended every 10 years. The vaccine may be bundled with other vaccines.

Adults

A booster shot is recommended for adults once every 10 years. This may be one of two vaccines, Tdap or Td, short for tetanus and diphtheria toxoids. If you weren't vaccinated against tetanus as a child or are not sure about your vaccination status, see your healthcare professional about getting the Tdap vaccine.

Pregnancy

Pregnant people can get the Tdap vaccine toward the end of pregnancy to give some protection for newborns against whooping cough.

Safety, side effects and precautions

DTaP and Tdap vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends the polio vaccine to protect against polio and its worst effects, including paralysis or an infection of the brain and spinal cord.

Poliovirus spreads easily through stool or from saliva as people cough or sneeze. The virus also can spread in water contaminated with stool from a person who has polio. While polio doesn't regularly show up in many countries, it does still spread to people who haven't had the polio vaccine.

Children and teens

The first dose of polio vaccine is due at age 2 months. The vaccine helps prevent the risk of death from polio and paralysis that doesn't go away. It helps prevent muscle shortening that causes bone or joint changes, as well as pain that lasts after the illness. The polio vaccine also helps prevent the return of symptoms or new symptoms decades after illness, called post-polio syndrome.

Safety, side effects and precautions

Polio vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends getting the Haemophilus influenzae type B (Hib) vaccine. It prevents bacterial infections that come on fast and that can cause blood poisoning and brain infection.

Children and teens

Newborns may have some protection from the Hib bacteria from a birth parent. But as they age, that protection wanes. The Hib vaccine helps boost protection until the child's immune system is strong enough to quickly respond and prevent bacteria from causing serious illness.

Serious illness from Hib includes:

• Brain and spinal cord infection called meningitis that may cause lasting health issues such as paralysis or death.
• Windpipe infection called epiglottitis that can cause trouble breathing.
• Bloodstream infections called sepsis.
• Skin infection called cellulitis.
• Lung infection called pneumonia.
• Joint infection that causes arthritis.

The Hib vaccine helps protect children age 2 months and older. A common recommendation worldwide is for babies and children to get the Hib vaccine at ages 2 months, 4 months, and 6 months, and the last dose by 18 months. A Hib vaccine may be given alone or with other vaccines.

Safety, side effects and precautions

Hib vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends getting a hepatitis vaccine to protect against liver infection and help stop the virus from spreading. The hepatitis A virus spreads easily through food, water or direct contact with infected stool.

Children and teens

The first dose of hepatitis A is recommended at age 12 months. The second dose is given 6 to 18 months later. This virus spreads through stool, so children who are in diapers may spread it to caregivers. Even though toddlers often have only mild illness with hepatitis A, adult caregivers can get very ill. The hepatitis A vaccine helps prevent short-term liver damage causing weeks to months of jaundice, fatigue, and fever as well as rare, overwhelming infections that lead to liver failure.

Safety, side effects and precautions

Hepatitis A vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends the measles, mumps and rubella (MMR) vaccine to help prevent infections from viruses that may be deadly or cause lasting health conditions.

Children and teens

The first dose of the MMR vaccine series is due for children at 12 months of age. The second dose of MMR may be given at 4 to 6 years of age as a combined vaccine that also protects against chickenpox, also called varicella. The combination vaccine is called MMRV.

The vaccine helps prevent the high fever, rash, pneumonia or brain swelling that may be caused by measles. It also protects against brain or nervous system illness that can happen years after infection. The MMR vaccine protects against painful swelling of the cheek glands and against infections of the brain and spinal cord caused by mumps. It also may protect against lower sperm production and male fertility concerns caused by mumps. The vaccine protects against the spread of measles, mumps or rubella to people at higher risk of harms. For example, rubella infection during pregnancy may cause miscarriage, stillbirth, deafness, blindness and brain damage in the child.

Safety, side effects and precautions

Measles, mumps and rubella vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends getting the varicella vaccine to protect against the varicella-zoster virus. This virus causes chickenpox. Chickenpox, also called varicella, leads to an itchy rash with small, fluid-filled blisters. Most cases are mild. But chickenpox can require treatment with antibiotics or hospital care. Rarely, chickenpox can lead to death. Later in life, the infection can reactivate as shingles.

Children and teens

The first dose of the varicella vaccine is generally recommended at 12 months of age. The second dose is due between ages 4 and 6. This vaccine may be given alone or as a combination vaccine containing the measles, mumps and rubella vaccine. That combination vaccine is called MMRV.

Varicella vaccine helps prevent the rare risk of death from chickenpox. The vaccines help prevent infections of the skin caused by the rash. They help prevent lung infections called pneumonia and brain infections called encephalitis. The vaccines also help prevent dehydration due to chickenpox symptoms.

Safety, side effects and precautions

Varicella vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends getting a shingles vaccine to protect against symptoms and complications from herpes zoster infection, even if you've already had shingles. The disease is caused by the same virus that causes chickenpox. After having chickenpox, often in childhood, the virus stays in nerve cells. Years or decades later, it can reactivate and begin to spread, causing herpes zoster, also known as shingles.

Adults

Shingles vaccine recommendations vary by country. But in many places, including the United States, health experts recommend people age 50 and older get the shingles vaccine. The vaccine also may be recommended for adults who have weakened immune systems.

The burning or tingling pain from the shingles rash can interfere with daily life. If the rash is near the eye, it can lead to vision loss or blindness. For some people, the pain from shingles continues after the rash goes away. This long-lasting pain is a condition called postherpetic neuralgia. It may last for months or longer. The pain can be sharp, or the area may feel itchy or numb. Postherpetic neuralgia can lead to sleeping issues, distress and a lower quality of life.

The current shingles vaccine is not a live virus vaccine. It's made from only part of the virus. The vaccine is given in two doses. The second dose is given 2 to 6 months after the first. Some people get shingles even with the vaccine. But the vaccine may make the illness milder and help it clear up faster. The vaccine has been shown to protect against shingles and postherpetic neuralgia for at least 10 years.

Safety, side effects and precautions

Shingles vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends starting the human papillomavirus (HPV) vaccine at age 9 to prevent future cancers.

Children and teens

The HPV vaccine series can start at age 9. It protects children against future cancers and the risk of genital warts caused by HPV. The virus spreads mainly by skin-to-skin contact and sexual contact. Often an HPV infection clears on its own, but some HPV strains stay active in the body. These strains may cause genital warts or lead to cancer years later, including cancer of the cervix, vagina, vulva, anus, penis or throat. Research has shown that receiving the vaccine at a young age isn't linked to an earlier start of sexual activity. The vaccine is given in two doses for children with typical immune systems who had their first dose before age 15. People age 15 and older, or who have a weakened immune system get three doses of the vaccine.

Adults

The HPV vaccine works best when the series is completed long before you are exposed to human papillomavirus. People who are 27 years to 45 years should talk with their healthcare teams about the benefits of getting an HPV vaccine. Most people get infected with a cancer-causing strain of HPV soon after they become sexually active. But even if you already have one of the strains of HPV, you may still benefit from the vaccine. It can protect you from other strains that you don't yet have.

Pregnancy

HPV vaccine isn't recommended during pregnancy. But if you get the vaccine before you know you are pregnant, the available data, though limited, have not shown safety concerns.

Safety, side effects and precautions

HPV vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

Mayo Clinic recommends getting a meningococcal ACWY vaccine to protect against Neisseria meningitidis bacteria that can lead to deadly infections. The bacteria spread quickly once in the body and can be life-threatening in hours.

Children and teens

The meningococcal ACWY vaccine series is often given at age 11 or 12 and again at age 16. This vaccine helps prevent infections of the brain and spinal cord, called meningitis, and bloodstream infections, called sepsis. The meningococcal vaccine helps prevent complications from infection, such as organ damage, limb amputation, hearing loss, brain damage and seizures.

Safety, side effects and precautions

Meningococcal ACWY vaccines have been carefully studied and are monitored for safety. Search the drugs and supplements database to find details on side effects and precautions for vaccine and immunization medicines.

If you have risks due to work, travel, health or habits, your healthcare professional may suggest other vaccines. If you don't have a record of getting a vaccine in childhood, your healthcare professional may recommend that you get it as an adult.

Getting the recommended immunizations helps keep you healthy. Immunization also may protect those around you. If you have questions about vaccines or immunization, talk with your healthcare professional.