In the past parents would hold say chicken pox parties, so all the kids would get the childhood disease and have natural immunity. Today, vaccines are the magic bullet, but we are no longer permitted to criticise them. However, there is still a body of evidence that indicates that getting childhood diseases had an important role in preventing various cancers in adulthood. For what it is worth, here are some links, some a bit technical, but included is a more readable account:
https://www.sciencedirect.com/science/article/pii/S030698779890055X
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2951028/
https://www.news-medical.net/news/20180522/Childhood-leukemia-linked-to-lack-of-childhood-infections.aspx
“Lack of infections during childhood is a common trend in obsessively clean environments that the babies grow up in today. According to Prof Mel Greaves from the Institute of Cancer Research in London, winner of the Royal Society’s prestigious Royal Medal, childhood leukemias are caused not just due to aberrant genetics or due to exposure to dangerous radiation but also due to lack of common infections during childhood that help build immunity. Greaves’s theories and evidence from the earlier works have been released in a paper that was published in the latest issue of the journal Nature Reviews Cancer. His work compiles information from globally situated experts in cell biology, immunology, genetics, childhood leukemia and epidemiology.
This finding comes after over three decades of research. According to Greaves, childhood cancers are preventable and part of the answer to the question could be to allow more social and environmental exposure to the babies especially at daycare centres to expose them to germs that would strengthen their immunity. Greaves looked at years of work on acute lymphoblastic leukaemia (ALL) and has come to this conclusion. Earlier on ALL was a fatal form of childhood cancer but today with advancement of cancer treatment over 90 percent of children diagnosed with this cancer can be cured. According to Greaves the cause of this form of childhood cancer is a “triple whammy”. At least one in 20 children carry genetic mutations that raise their risk of getting the cancer. These mutations may remain dormant if the immune systems of the children are normally functioning.
For the immune systems to function properly, it is imperative that the babies are exposed to bacteria and viruses right from infancy. Children who have a weak immunity due to lack of exposure to bacteria and common viruses, when exposed to them later may develop a second genetic mutation that raises their risk of getting leukemias and cancers. According to Greaves, his argument is supported by the fact that more and more affluent populations are seeing children with ALL. The incidence of ALL risen by 1 percent per year globally. He explained that this rise has to do something with the modern lifestyles that the children are exposed to. He said that the problem here is not infection but the lack of it. According to him, same theory applies for several other diseases including type 1 diabetes, multiple sclerosis and Hodgkin’s lymphoma as well as a several allergic diseases. He pointed out that the rates of all of these diseases are lower in the poorest countries and higher in affluent countries.”
https://www.youtube.com/watch?v=hI3wrKpxySA
It is simply too bad that we no longer have the freedom of speech to investigate, and propagate such beliefs.