Many countries have national vaccination campaigns that consists of vaccines against several different diseases. I expect that the choice of vaccines that are included in such programs is mainly political, cost-related and possibly has something to do with history and even climate. But I wonder: why would one not simply take all available vaccines or at least all vaccines with a long protection duration, such as the:

  • MMR (Mumps, Measles, Rubella) vaccine - lifetime protection
  • BCG (Bacillus Calmette-Guérin) vaccine (Tuberculosis) - lifetime protection
  • Rabies vaccine - lifetime protection
  • Hepatitis B vaccine - lifetime protection
  • Yellow Fever vaccine - lifetime protection
  • Meningococcus (C) vaccine - lifetime protection?
  • Hepatitis A vaccine - 30 year?

Or even vaccines with a "shorter" protection duration such as:

  • Diphtheria, whooping cough, tetanus and polio vaccine - 10 year
  • HPV vaccine - 6-8 year
  • Japanese encephalitis vaccine - 5 year
  • Meningococcus (ACW135Y) vaccine - 5 year
  • Pneumococcal vaccine - 5 year
  • Typhoid fever vaccine - 3 year
  • Tick-borne encephalitis vaccine - 3 year

Above mention protection durations do not take into account the amount of protection (efficacy).

The Influenza vaccines need to change constantly as the virus also changes, so I understand that a new flushot is required every year. A gut-feeling tells me that the COVID-vaccine also requires booster shots every 6-36 months at least till the pandemic has officially ended.

These are just some vaccines as an example but my question is broader than this vaccines. For any given vaccine, with or without long-term protection. Why would one NOT take all available vaccines (periodically)? Another reason why I ask is also because I recently read more and more about the so called "trained-immunity" and "cross-immunity". So does, and if so how, does taking all available vaccines contribute to cross- and trained immunity? And would there be a medical reason not to add all vaccines to such national vaccination campaigns?

I'm especially impressed by how the HPV vaccine seems to decrease the chance of certain types of cancers as well and how the BCG vaccine seems to affect the "strength" of the overall immune system response, if I understand the matter correctly. Some people have side-effects after vaccination but I generally think those side-effects outweigh the risks of the actual diseases by far. For this reason, I'm very grateful to be alive in a time where we have so much science and technology to provide us with all the necessary knowledge to deal with this. All current vaccines and future (mRNA-)vaccines (which I expect a lot from) seem to me as an almost free security patch to the human immune system. Almost like a software update, so to speak.

Please let's exclude all personal objections of typical antivaxxers. I'm purely interested in why one would technically, medically, scientifically not want to take all vaccines available. Even if a disease only exist on the other side of the world in a country you're never gonna visit, wouldn't generally training the immune system and possibly give some (unknown) cross-immunity outweigh the possible downsides?

Additionally: Have studies been performed to study the effect on the immune system when a high variety of vaccines are used on a person and/or how (much) these vaccines affect each other and/or contribute positively or negatively to the overall cross and trained immunity of a person.

  • Cost? Or for the current pandemic where vaccine supply is much smaller than the population needing it, not being inordinately selfish? Rare side effects exceeding disease probability if the infection chance is miniscule? Jul 22 at 14:07
  • @BryanKrause cost- and availability related reasons I understand. But let's assume for the sake of this question that all vaccines are cheap and available for the whole world population. It's also not specifically about COVID or this pandemic. I'm searching for technical/medical reasons why not to, especially in relation to cross- and trained immunity.
    – Bob Ortiz
    Jul 22 at 15:09
  • How do you imagine this question can be answered with something other than opinion?
    – Carey Gregory
    Jul 22 at 19:36
  • You say "assuming all the things people who don't want vaccines think are untrue, why wouldn't everyone want all the vaccines?" - I mean I agree those things are untrue, but believing those untrue things is why people don't want all the vaccines. Jul 23 at 1:32
  • @CareyGregory fair point. Maybe the question should be "Does taking all available vaccines contribute to cross- and trained immunity?" or broader "What are the pros and cons of taking all available vaccines?". Because I'm not interested in opinion. I wonder if there are medical, technical reasons, evidence based, that should prevent someone from doing so and is there any proof that taking all vaccines does somehow positively contribute to cross- and trained immunity.
    – Bob Ortiz
    Jul 23 at 7:25

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