There is no evidence that mRNA-based COVID-19 vaccines will use hydrogels. There is no evidence of a hydrogel that will connect you to the internet or alter your DNA.
As reported by Pablo Rougerie at Health Feedback...
Incorrect: The claim incorrectly alleges that mRNA-based COVID-19 vaccines will modify the human genome, even though they cannot be integrated into the DNA-based genome. In addition, hydrogel-based sensors do not connect themselves to the internet.
Unsupported: The social media posts do not present supporting evidence for the claim that mRNA-based COVID-19 vaccines will use hydrogels.
Misleading: The claim describes hydrogels as a recent groundbreaking invention, however, they were discovered decades ago and have been extensively used in biomaterial and biomedical research.