You can actually catch the disease being vaccinated against from some traditional vaccines.
Some of the COVID vaccines contain a genetically altered adenovirus that will infect a number of cells and make them produce the COVID spike proteins. This causes a limited number of 'zombie' cells to trigger the immune response that will also protect against the COVID virus. The number of cells infected is limited by the dosage received because the adenoviruses are altered so the protein and not more virus is produced.
Even traditional vaccines have severe side effects for a tiny number of recipients.
This mutated virus technique is well understood and is used in other therapies to treat genetic diseases where the body doesn't produce certain needed proteins.
Stop scaremongering.
mRNA or viral vector therapies have not been approved for non-experimental or non-emergency use in humans.
Even sub-unit vaccines are new technology, with a few new vaccines being approved.
Interesting that China is focusing on whole virus vaccines while the West is focused on unproven technology.