A Hib vaccine is a vaccine that helps protect against infection by the Haemophilus influenzae bacteria type b (Hib). It usually works by prompting the immune system to create antibodies against the bacteria, which can help a person fight off the infection if they later come into contact with the bacteria. Usually given as a series of injections, Hib immunization is generally recommended during early childhood, as children under the age of five are at greatest risk of Hib infection. While it is generally considered safe for most people, there is a chance of experiencing certain side effects from a Hib vaccine, and there are certain people for whom it is not recommended by experts.
As with most vaccines, a Hib immunization aims to mimic the body's natural immune response. When a person is infected with Hib, their immune system creates special antibodies designed to help fight the bacteria, although serious health problems, including meningitis, pneumonia, and even death, can occur as the bacteria spread throughout the body before this immune response is fully activated. A Hib immunization can help prevent such complications by prompting the body to create Hib antibodies before an infection actually exists. It does this by introducing a small amount of inactive Hib into the body, which causes the immune system to create specific antibodies, but does not actually cause Hib infection. If a person later comes into contact with Hib, they should be able to avoid getting seriously ill because the immune system will be able to fight off the bacteria early on.
The Hib immunization series is usually given during early childhood. This is because Hib most commonly affects children under the age of five. To ensure long-lasting immunity against Hib, health care providers generally recommend that children receive multiple doses of the vaccine given over a period of about a year, often starting at two months of age. There are several versions of the Hib vaccine, and the exact number and timing of doses needed may vary depending on the version used. In addition to young children, experts may also recommend the Hib immunization series for people with weakened immune systems, such as those who have HIV or who are taking chemotherapy.
Many people who receive the Hib vaccine do not experience any side effects. If side effects do occur, they are usually mild and may include a low-grade fever and swelling where the injection was given. In rare cases, serious side effects such as allergic reaction, seizures, and difficulty breathing can occur. Experts generally recommend that no more doses of Hib vaccine be used in people who have had an allergic reaction. They also generally recommend against giving Hib vaccine to children younger than six weeks of age and to people who are more than mildly ill at the time vaccination is considered.