There is no-see-um netting made. I bought some, years ago, from a camping supplies store. The downside is that it is so fine that it really impedes air flow.
What I use now is mosquito netting, but I spray it with "surface spray" (against in-flying cockroaches) , and then the no see um's seem to just avoid the area altogether. I do all the screens in one go, and re-do 'em if I get invaders.
No see ums can't bite you through cloth, which for me means gauzy cover-up style clothing
where they are rampant. I hate 'em!
Treating bites with diphenhydramine, for the allergic reaction, and rubbing the bites with ice cubes helps give some symptomatic relief.
Some people find that lavender oil
will keep them off you. And you can try DEET or other insect repellents, but the stuff's so gluggy on my skin, I don't like it.