Vaccines prevent diseases and reduce the chances of people getting sick or dying. This improves children’s health, so they can grow up to be healthy adults who can work, care for their families and contribute to society. It also reduces the burden on healthcare systems, by cutting down hospital visits and the number of days people are sick.
During vaccine development, medical researchers identify parts of bacteria or viruses that stimulate the immune system. They then create a weakened (attenuated) version of the germ and add it to the vaccine. The vaccine contains other ingredients, including adjuvants and stabilizers, to ensure it works well and is safe.
When the immune system is exposed to an antigen, it responds by creating antibodies that target and destroy the disease-causing pathogens. The antibodies keep the pathogens from entering cells and causing infection. Some vaccines contain a live virus or bacterium that has been weakened, while others use a killed (inactivated) form of the organism or instructions for the body to make proteins that look like the harmful ones.
Most people have no problems with vaccination, and serious allergic reactions are very rare. If you or your child does have a reaction, the person who gives you the vaccine is trained to deal with it quickly. They may give you an adrenaline injection if the reaction is severe. This helps prevent a shock and keeps the allergy from getting worse. Vaccines have significantly reduced many infectious diseases that often made children and adults seriously ill, such as smallpox and polio. However, these diseases still exist in the world and can cause serious illness and even death, especially among infants and people with weakened immune systems. High levels of vaccination provide everyone with protection from those diseases, which is called herd immunity.