Innocent.
The goverment should only have the power to mandate vaccines if they provide the means to pay for said vaccine. If the goverment lady showed up at the kid's door and would vaccinate him for free, then he would be guilty.
As not, innocent.
Plus, PROVE that the boy was the one who gave the measles to her. Just because you were in the vicinity of a murder with a bullet in your pocket does not mean your a guilty.
Also, how did the girl get measles if she was vaccinated, too? Hypocrite much?