If DU has a (sub-)forum for "alternative" medicines and "natural" remedies, that would probably have some anti-vaxxers. A (sub-)forum for back-to-nature and live-off-the-land types would probably have some. Basically any (sub-)group that is about rejection of many modern technologies (e.g. "organic" foods), especially "Western Medicine". Folks like that are not intrinsically left-leaning, but many are. So any DU-folk who are in that kind of sub-cultural range who have not posted an "I am vaxxed" virtue-signal are possible anti-vaxxers who are laying low.
The huge difference in politics; I’ve seen no one on here that had bragged about getting the shot. Yes, I’ve seen several post they’ve been vaccinated, but not bragged. I’ve seen several who’ve mentioned they’re not vaccinated, without recrimination.
If you posted at the DUmp you weren’t vaccinated and weren’t going to be, they’d ban you.
KC