There are many vaccines available, with the exact number depending on how you categorize them. As of 2023, effective vaccines exist against at least 33 human diseases. However, multiple vaccines may exist for a single disease, and new vaccines are constantly being developed. Additionally, different formulations of the same vaccine (e.g., different dosages or delivery methods) might be counted separately.
Several sources provide different numbers:
- The CDC mentions more than 25 safe and effective vaccines to prevent various diseases. https://www.cdc.gov/global-immunization/fast-facts/index.html
- The WHO provides a list of diseases with available vaccines, but doesn't give a total count. https://www.who.int/teams/immunization-vaccines-and-biologicals/diseases
- One source specifies that as of 2023, vaccines exist for 33 human diseases.
It's important to distinguish between vaccines for disease prevention and those used as cancer treatments. Cancer vaccines aim to stimulate the immune system to fight existing cancer, unlike preventative vaccines.
The development of vaccines is ongoing; new vaccines are constantly created and improved upon, leading to a fluctuating total number.
Therefore, while a precise number is difficult to state definitively, it's safe to say that many dozens of vaccines exist, protecting against various infectious diseases and, in some cases, cancers.
