As a group they would be less prone to infection from without but much more vulnerable once it is within the group.There's an interesting situation in Canada revolving around a certain minority group who seem to be experiencing unusually high rates of COVID-19 infection. The press are tiptoeing around the subject so it's hard to find a news story which is willing to put their cards on the table and say what they mean instead of waffling about and telling people to show compassion and not discriminate against them. From the sounds of things they must be getting absolutely hammered for it to be making the news multiple times.
They're a group who refuse to integrate with the rest of society, who keep their own language, religious customs, and distinctive form of dress and don't associate with others outside their group.
You all know exactly whom I'm talking about. Yes, it's "low germans", which seems to be the new politically correct way of referring to them, as opposed to "Mennonites" as most people know them. There's also been vague mention of Doukhobors and Hutterites being hit as well, although I don't hear as much about them as unlike the Mennonites they don't live in my area.
They live in relatively sparsely inhabited rural areas, don't take public transit, don't deal with the general public on a frequent face to face basis, and don't have any of the usual high risk factors people associate with COVID-19. The problems seem to revolve around their lifestyle, where they engage in communal meals, regular religious gatherings, and inadequate social distancing. COVID-19 can spread rapidly in that sort of environment once it finds a way in, and so it has.
This may not be earth-shattering news, but it's an interesting situation to keep in mind when thinking about how COVID-19 spreads in different societies.