ETA: Ya know, the woman would have to ask, EVERYONE EVERYWHERE, about their vaccines. That is impossible. She can't expect everyone everywhere, everywhere she goes, to answer this question.
Not only, your co-op, group.
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The group or Co-Op... as a whole, should decide about this?
Since they are an organized, organization.
I can understand you and your Husband's feelings on this.
In my State, there was a baby that died, from Pertussis. A 6 month old baby. Which was not, vaccinated. Prior to their baby dying, the parents were against vaccinations. And went that route. Their baby got sick, it turned out to be Pertussis. And the baby died. The baby got it from a relative. Who thought she just had a regular cold. Now that their baby died, the parents are advocates, of getting vaccinated. And for getting, Booster shots for Pertussis, in teens and adults.
You should not, if you can, get into a long personal heated conversational debate about this, with her.
If she tries to, that is.
Don't argue with her, if she goes that route.
Just keep telling her it is a personal choice.