Immunization glossary


Definitions of medical terms

Immunizations (also known as "vaccinations") are an important part of preventive health care for you and your family.

What is an immunization?

Girl getting a band-aid after a shotImmunizations can help your body develop resistance to specific diseases and increase your immunity.

You are typically given an immunization, or vaccine, as an injection. Each vaccine contains small doses of killed microorganisms or weakened live organisms, which stimulate your immune system to produce antibodies against a disease. If you are later exposed to the disease, these antibodies can recognize and fight it. An immunization can significantly lower the impact of a disease, or protect you from catching it altogether.

Diphtheria, tetanus, and pertussis vaccines

Common abbreviations

DTaP: Diphtheria, tetanus ("lockjaw"), and acellular pertussis ("whooping cough")
Td: Tetanus and diphtheria
Tdap: Tetanus, diphtheria, acellular pertussis

These combination vaccines provide protection from bacterial infections that, before the vaccines became available, were once common, serious illnesses. Most are given to infants as a series of injections, with boosters given later in life. The immunization is usually given as a series of 4 to 5 doses. A Tdap booster is recommended for all women in the third trimester of every pregnancy.

Haemophilus influenzae type b vaccine

Common abbreviations

Hib: Haemophilus influenzae type b

Haemophilus influenzae type b infection is most common in young children and can cause serious diseases including meningitis and pneumonia. Even though it has "influenzae" as part of its name, it is a bacterial infection, not the flu, which is caused by a virus. The Hib vaccination protects against Hib infection only, not the flu. The immunization is usually given to infants or children as a series of 3 to 4 doses.

Hepatitis B vaccine

Common abbreviations

Hep B: Hepatitis B

This immunization can prevent hepatitis B, a viral infection that can cause serious liver damage, including cirrhosis (liver scarring) and liver cancer. It is usually given as a series of 3 injections and is recommended for all children and any adults who are at risk of hepatitis B exposure (for example, health care workers or those who often travel in parts of Asia or Africa).

Human papillomavirus vaccine

Common abbreviations

HPV: Human papillomavirus

Human papillomavirus (HPV) is the most common sexually transmitted virus. Most HPV infections occur without any symptoms or treatment. However, some HPV infections can persist for years. Such infections are the primary cause of cervical cancer.

HPV vaccine can protect females from 9 types of HPV that cause 70 percent of cervical cancers and 90 percent of genital warts. The HPV vaccine is given as a 2- or 3-dose series for boys and girls starting at age 11 to 12 years. The series may be given up to age 26.

Influenza (flu) vaccine

Common abbreviations

Flu: Influenza

The flu is a very contagious viral illness. Flu symptoms include fever, headache, cough, fatigue, and muscle aches. Flu season usually starts in late fall and lasts through early spring. Since a different flu strain appears each year, a new vaccination is required yearly.

There are 2 types of immunizations you can get for the flu: an intranasal spray or an injection. An annual flu vaccination is recommended for all persons 6 months and older. The flu vaccine is especially recommended for children ages 6 months to 18 years, older adults, those with certain medical conditions, women who will be pregnant during flu season, and those who live or work in situations where contact with the influenza virus is more likely or who live in close contact with someone at high-risk for complications from the flu.

Measles, mumps, and rubella vaccines

Common abbreviations

MMR: Measles, mumps, and rubella ("German measles")
MR: Measles and rubella

Measles, mumps, and rubella were once common childhood illnesses in the United States. Today, these illnesses are rare because of widespread MMR vaccinations. They are usually given to infants and children before entering school, but may be given to teens and adults as well. Most health care workers, especially those who come in contact with pregnant women, must either prove they are immune to rubella, or receive the immunization. This vaccine is given as a 2-dose series.

Pneumococcal vaccine

Common abbreviations

PPV: pneumococcal polysaccharide
PCV: pneumococcal conjugate

Pneumococcal vaccines prevent several types of infections caused by the bacterium pneumococcus (also known as "Strep. pneumoniae"), including meningitis and pneumonia. PPV is usually recommended for adults at risk for this infection, such as the elderly or those with certain medical conditions. PCV is recommended for most children, and is given as a series of 4 injections. For all adults 65 and older, PCV13 is recommended followed by PPSV23 from 6 to 12 months later. PCV is also recommended for immunocompromised adults at high risk of severe infection, such as patients without a spleen, patients with leukemia, lymphoma, kidney failure, and organ transplantation.

Polio vaccine

Common abbreviations

IPV: inactivated poliovirus vaccine

The polio vaccine can prevent polio, a serious viral infection that can lead to disability and paralysis. It contains an inactivated virus (one that can't cause the disease) and is recommended for children as a series of 4 injections. Adults usually aren't vaccinated with the polio vaccine unless they are planning to travel to an area of the world where polio still exists.

Reviewed by: Craig W. Robbins, MD, January 2019

© 2015 Kaiser Permanente