I read an article that claimed COVID-19 cases are much higher and common in countries with high gluten diets. What do you think?

There's no proof of that. And the presence or absence of gluten in the diet has no effect on the virus.

I think this has nothing to do with primary and secondary education

That sounds like phony science to me. For one thing, the amount of gluten in, for example, wheat products varies a great deal from place to place. Wheat in the US is something like 11% higher in gluten, which may be why so many people are sensitive to it. Then there's the issue of confusing correlation with cause and effect. Sure, many Asian countries have controlled COVID better, and their diet is mostly rice BUT the real reason they were able to contain the virus is because of stricter government actions and more compliance among members of collective cultures. Someday, all the evidence will be sifted through, and we may know more about why some people got sicker than others, but right now, the correlations we know about are age, underlying health problems such as heart and lung disease, diabetes and obesity, and degree of exposure. 

no idea.  i didn't see that article and you didn't tell us where to find it.

It is more common in obese people here in the U.K. perhaps that is what it meant.

I think this has nothing to do with primary and secondary education

that makes absolutely no sense