I would argue that they should respond by getting the vaccinations. I do not see anything sinister about the government requiring people to get vaccinated against epidemic diseases. It is an important matter of public health and there is no real reason to resist.
It is important to require that people get vaccinated so that our public health will not suffer. If we leave it up to people to get vaccinated on their own, too many of them will forget or will not bother. This will lead to public health problems as many children fall victim to diseases that are easily prevented through inoculation.
I think that it is perfectly reasonable for the government to take steps, including mandatory vaccination, to preserve public health.
This is an interesting question, and one that has different possible answers. The REAL question is how each individual in a society WOULD respond to a forced program of vaccinations. It may be difficult to say SHOULD because there may be no correct answer.
First, one would have to decide the reason behind a mass vaccination. Assuming this occurred in a free, democratic country, one could assume that the order would be given in the face of severe danger to the public health. If conditions were that dangerous, most people would probably be very WILLING to get vaccinations without being ordered to.
Secondly, one would have to decide on his personal feelings regarding government intrusion. For example, certain diseases can be "wiped out" if everyone is immune to them, but if a sub-population refuses to be vaccinated the disease can linger and re-emerge. Which is more important? Public safety or personal rights?
There is already a program of "semi-mandatory" vaccinations that are required for children to attend school. Though I suppose you could avoid this by not sending your child to school, or by claiming a religious exemption, it pretty much forces most people to comply. How should people respond to this? Look at how the HAVE. A little grumbling, maybe, but general acceptance because most people feel that the benefit of the vaccinations outweighs any risk.
In general, one might say that the public's reaction to a program of forced vaccinations should be determined by the severity of the situation.