Due to the success of immunization, some diseases are no longer perceived as a threat. Certain groups have even questioned the utility of vaccination in spite of its proven success in controlling disease. In recent years, a number of web sites providing unbalanced, misleading and alarming vaccine safety information have been established, which can lead to undue fears, particularly among parents and patients. 

Vaccines are safe. Any licensed vaccine is rigorously tested across multiple phases of trials before it is approved for use, and regularly reassessed once it is on the market. Scientists are also constantly monitoring information from several sources for any sign that a vaccine may cause an adverse event. Most vaccine reactions are usually minor and temporary, such as a sore arm or mild fever. In the rare event a serious side effect is reported, it is immediately investigated.

It is far more likely to be seriously injured by a vaccine-preventable disease than by a vaccine. For example, in the case of polio, the disease can cause paralysis, measles can cause encephalitis and blindness, and some vaccine-preventable diseases can even result in death. While any serious injury or death caused by vaccines is one too many, the benefits of vaccination greatly outweigh the risks, and many more illness and deaths would occur without vaccines.

Scientific evidence shows that giving several vaccines at the same time has no negative effect on a child’s immune system. Children are exposed to several hundred foreign substances that trigger an immune response every day. The simple act of eating food introduces new antigens into the body, and numerous bacteria live in the mouth and nose. A child is exposed to far more antigens from a common cold or sore throat than they are from vaccines.

The key advantage of having several vaccines at once is fewer clinic visits, which saves time and money. Also, when a combined vaccination is possible (e.g. for diphtheria, pertussis and tetanus), that will result in fewer injections and reduces discomfort for the child. A number of steps can also be taken to reduce pain at the time of vaccination.

Information adapted from the World Health Organization Vaccine Safety Net.