The vaccine against whooping cough, tetanus, and diphtheria is an old vaccine, but the version of the vaccine your child is getting is relatively new. The newer version of this vaccine was introduced in 2000 to reduce side effects resulting from the older vaccine.
The D in DTaP represents diphtheria, an infection that is associated with severe cough and seizures. The T in DTaP stands for tetanus, which is an infection that is commonly known as lockjaw. The a in DTaP was added in 2000 to distinguish the newer version of this vaccine from the older type, which was manufactured differently. Finally, the P in DTaP is the pertussis component of the vaccine. Pertussis is also known as whooping cough. All three infections will be described individually in detail in the following sections.
The DTaP vaccine is one of the oldest vaccines. The tetanus vaccine became available in 1924, and the diphtheria vaccine came out in the same year. When these two vaccines were first developed, treatment for these infections was dangerous and frequently unavailable to those who needed them. Due to the effectiveness of these vaccines, you probably never heard of anyone with these conditions. The whooping cough vaccine was invented in 1926, and these three vaccines were combined in the mid-1940s to decrease the number of injections children receive.
This vaccine has undergone much evolution in the past decades, and the reason for the changes is primarily to reduce the side effects associated with this vaccine. The older version of this vaccine, called the DTP vaccine (or the whole-cell DTP vaccine), used to cause fever in children up to half of the time after its administration. In addition, it was associated with swelling of the brain in rare circumstances. It is believed that the way the older vaccine was manufactured was responsible for these side effects. The pertussis component of the older vaccine was made from the entire germ that causes whooping cough, which is why it was called the whole-cell DTP vaccine. The current version of the vaccine was introduced in 2000, and the new DTaP vaccine is manufactured from parts of the pertussis bacteria instead of the entire germ. Since its introduction, it is clear that the chance of having swelling at the injection site, fever, and loss of appetite is much lower than in the past with the older whole-cell vaccine.