The immune system is your primary defense against germs and microorganisms that can invade your body and cause infection. It’s made up of proteins, cells, tissues, and organs that, when a threat is detected, produce substances known as antibodies. Each antibody is uniquely designed to attack specific threats to the body.

A vaccine stimulates the production of antibodies by introducing weakened or inactive bacteria or viruses or a portion of a germ’s structure into your body. While vaccines are not capable of causing a severe infection, your immune system identifies the weakened or inactive germs and produces antibodies strong enough to protect you from becoming sick.

Not only are vaccinations a safe way of preventing diseases, they can also improve the health of large groups of people at a very low cost. In the last half century, vaccines have changed the lives of people around the world by eradicating smallpox and reducing the occurrence of common diseases such as polio, typhoid fever, and measles. Countries with weak health systems have benefitted from large-scale vaccination programs because these initiatives require minimal training, equipment, long-term medications, or prolonged medical care. In the years to come, prevention will become an even greater tool to manage health care all across the globe.

Important vaccines

There are countless vaccines that exist today to protect individuals against many common – and potentially dangerous – diseases. Most people receive the majority of their vaccines when they are children. However, there are several vaccines of which every adult should be aware.

The flu, which is a layman’s term for influenza, is an infection caused by viruses that attack the nose, throat, and lungs. Influenza is most prevalent during the fall or winter months and is usually mild – though it sometimes can be severe or even fatal.

Flu vaccines are recommended for any adult who wants to reduce the risk of being infected with the influenza virus. A flu vaccine is also suggested for individuals who are at high risk of influenza complications or have close contact with individuals who are at risk. These high-risk categories include:

• People who are age 50 or older
• Women who are pregnant or expect to be pregnant during cold season
• Asthma sufferers
• People with heart, kidney, or liver problems
• Diabetics
• People who have a suppressed immune system
• Individuals who have suffered spinal cord injuries
• People who experience seizures or suffer from nerve or muscle disorders
• Residents of chronic care facilities or nursing homes
• People who care for children younger than 5 or adults older than 50
• Caretakers of persons with medical conditions that put them at high risk of complications from influenza

Yearly flu shots should be arranged before flu season starts or as early as possible during flu season, preferably in October or November.

The influenza vaccine is not recommended for:

• Infants under the age of 6 months
• Individuals who are allergic to eggs or egg products
• People who have developed a severe reaction to a flu vaccine in the past
• People who developed Guillain-Barré syndrome, a disorder of the nerves that affect the extremities, within six weeks after receiving a flu vaccine in the past

Pneumonia is a general term for the infection of the lungs caused by Streptococcus pneumonia bacteria. The pneumococcal vaccine is made up of a deactivated virus that offers protection against 23 types of Streptococcus pneumonia bacteria.

Individuals who are at higher risk of pneumonia are excellent candidates for the pneumococcal vaccine including:

• People aged 65 or older
• Residents of nursing homes or long-term care facilities
• Diabetics
• People with chronic lung or heart disease
• Individuals who have had their spleen removed
• People with weak immune systems

For most people, only one dose of the pneumonia vaccine is required during their lifetime. A second shot may be needed for seniors above the age of 65, organ transplant recipients, and individuals with a weak immune system who have not received a pneumococcal vaccine in the last five years. This vaccine is not recommended for children under the age of 2.

The Tdap vaccine is a mixture of three vaccines that immunize individuals against diphtheria, pertussis, and tetanus. Diphtheria is an upper respiratory infection that can lead to breathing problems, paralysis, and death. Pertussis, also known as whooping cough, is a contagious disease that is caused by the bacterium known as Bordetella pertussis. Tetanus, which is caused by Clostridium tetani bacteria, is a condition that occurs when lacerations or wounds become infected.

You may need to have the Tdap vaccine if:

• You are above the age of 18 and your last Tdap vaccine was more than 10 years ago (for seniors above 65, a tetanus-diphtheria booster is recommended)
• You have a wound that is likely to become infected and your last tetanus shot was more than five years ago
• You are in frequent contact with infants or are likely to become pregnant

If you have never received a Tdap vaccine, you can be vaccinated against those diseases by undergoing a series of three doses. After the first dose is administered, the second dose is given four weeks later. You should get the third dose six to twelve months after the second dose.

You should avoid getting a Tdap vaccine if you:

• Are sick
• Are pregnant
• Had an allergic reaction to a previous Tdap vaccination
• Experienced seizures or lapsed into a coma within seven days of receiving a previous Tdap vaccine.

In addition, a Tdap vaccine is not recommended for children under the age of seven. Instead, a DTaP vaccine, which contains kid-appropriate dosages of the medicines present in the Tdap vaccine, should be administered to these children. Once these children reach the age of 11, it is recommended that they then get a dose of Tdap. For young children who should not receive a pertussis vaccine due to allergies or other reasons, a DT shot can be given to protect against diphtheria and tetanus.

Meningitis is the inflammation of the meninges, the tissue that envelops the brain and spinal cord. The most common form of meningitis is caused by a virus that enters the brain through the mouth and nose. Generally speaking, you only need to get a meningococcal vaccine if you:

• Were not vaccinated as a child
• Are living in a dormitory for the first time
• Are travelling to a place where meningitis is prevalent
• Live in a community where the risk of meningitis outbreak is high

Meningococcal vaccines are not recommended for people who are sick or have developed Guillain-Barré syndrome after being vaccinated for meningitis in the past.

Chickenpox is a contagious disease that causes blister-like red spots to appear all over the body. You might need to get a chickenpox vaccine if you have never had chickenpox. This is especially true for women who are planning to become pregnant and do not know if they are immune to chickenpox.

In children, the first dose of a chickenpox vaccine should be administered at the age of 12 to 15 months. When the child reaches age 4, he or she should receive the second dose. Teenagers, who have never been vaccinated against chickenpox, should receive two doses of the vaccine four to eight weeks apart.

The chickenpox vaccine is not recommended for people who:

• Have a weak immune system
• Are pregnant or plan to become pregnant within four weeks of being vaccinated
• Are allergic to neomycin medication or gelatin
• Are currently taking medications containing aspirin or any of its derivatives