Do vaccines confer immunity?

An old myth that is recirculating claims that vaccines didn’t cut death rates, that they hurt your immune system, making unvaccinated kids healthier, and that the CDC is hiding studies comparing vaccinated and unvaccinated people.

The graphs that these claims rely on are found here. They show that deaths had already drastically fallen before vaccines. Cases, on the other hand, didn’t fall until vaccines were introduced. Smallpox eradication is a good example of zero cases meaning zero deaths, too. Since the worldwide effort to get rid of smallpox, there hasn’t been a single case anywhere, which shows that vaccines stopped it.

Anti-vaxxers claim that unvaccinated children are healthier than vaccinated children in myriad ways. They often cite some studies to try to back up those claims. However, all these studies suffer from a lot of the same fallacies. Many are simple surveys.

Surveys are often victims of self-selection bias, or volunteer bias, in which participants can decide whether or not to participate in the study, along with recall bias and reporting bias.
Many large studies in the real world have looked into whether children who get vaccines do worse than children who do not. The answer is no. One Danish study followed more than 650,000 children for ten years and found that MMR vaccination did not cause autism, even in children who already had a sibling with autism.

Another meta-analysis combined data on 1.2 million children from five countries and came to the same conclusion for autism and every other long‑term health problem it examined. Studies from Germany, the Philippines, and several U.S. health systems show the same thing: the main difference is that vaccinated kids are protected from the diseases the vaccines are made to prevent.