Sorry that your friend is still unwell. The obvious answer is that she became infected at the supermarket. You can only do your best to avoid it. The advice in the US is that people should wear masks so it makes you wonder if this virus is airborne and you have to breathe. My husband is very vulnerable so I have only been out to walk the dog and have spent a lot of time organising deliveries. It's ok and important to remember why I doing it, not to save time but lives.
How do you acknowledge Easter.