Nowhere is it said that a Catholic sins by refusing a vaccine with remote material cooperation.  My personal belief is that one has the right to refuse a vaccine, however, one has not the right to place the health of others at risk.  If an unvaccinated person becomes ill or is possibly carrying a contagious disease, he is obliged to protect others by quarantining himself and perhaps his entire household to the extent deemed necessary by medical authorities.  This is what was done during outbreaks in the times prior to vaccines. The young man who refused the varicella vaccine was within his rights to do so because the cooperation with aborted fetal cells in the vaccine violated his conscience.  I do not agree that he had the right to attend school and play sports against outside teams thereby possibly spreading sickness to others.  I heard that he eventually caught the chicken pox, suffered a mild sickness and has fully recovered.  He needn’t expend any more time, money, or energy on his own particular case since he now is immune.  
I know of a middle-aged man who became critically ill and was hospitalized on a ventilator due to catching chicken pox.  This was before there was a vaccine.  He most likely contracted the disease in Church during a local outbreak.  Several families knowingly brought their sick children with them, figuring it didn’t matter.  The man recovered, but it was over a year before he was able to return to work.  In the meantime, his parents in their 70s took over the running of a dairy farm and supervision of six children while his wife took a factory job just to keep going.  They ended up nearly $90,000 in medical debt without medical insurance.  The parish helped somewhat, but nobody had that kind of money. The hospital eventually forgave the remainder.  If they hadn’t, they’d have lost their farm and means of livelihood.  Sure, he might have caught it anyway, somewhere else, but perhaps not.  At any count, people should bring sick children or themselves to church out of charity for others.  
Last Easter I didn’t go to Mass because I had the flu.  Why?  I could have pumped myself up on medications and gotten through it.  Because what if I gave it to an elderly person, an infant, a pregnant woman, or on of several medically fragile parishioners?  It wouldn’t be right.  Flu shot?  Some take them, some don’t.  They don’t use fetal cells or immorally obtained ingredients.  I actually got a flu shot last year, but it did no good because the strain I had wasn’t covered by the shot.  

If an unvaccinated person becomes ill or is possibly carrying a contagious disease, he is obliged to protect others by quarantining himself and perhaps his entire household to the extent deemed necessary by medical authorities.

Yes, a person who contracts the disease, REGARDLESS of whether he's unvaccinated or vaccinated (here you assume that only the unvaccinated can catch a particular illness), should quarantine himself.  You appear to imply that this duty falls only on the unvaccinated.  Now, as for the risk to the population, if you by vaccine propaganda, then there's no risk to the vaccinated from the unvaccinated, since the vaccinated are protected.

And, yes, I've known some Traditional Catholics who dragged sick kids into church, bragging about how "tough" they were, either out of scrupulosity or else self-righteousness, failing to take into account the requirements of charity.  If your kids are sick, KEEP THEM AT HOME.  You do NOT please God by taking them to church sick; you displease Him by doing something contrary to charity.