It seems to me that the current vaccines can’t stop covid. They reduce severity of illness a lot, but they don’t stop infection or transmission. They can’t do or we wouldn’t be seeing such high positive test numbers.
– “Lack of understanding doesn’t seem that likely…”
There are quite a lot of anti-vaxxers and denialists. I read today that in the US, 50% of Republicans in some states outright refuse to get vaccinated.
– “Could not speaking or reading English be one of the reasons?”
More likely illegal immigrant status. Craig posted about this a while back. Due to Theresa May’s “hostile environment” policy they’d need to identify themselves to get NHS registration. Remember that “health tourism” was a major Brexit selling point.
Not speaking English isn’t a likely reason because there will be news about vaccinations in the country they’re from or descended from.