Antivax was a monumental failure of the right. A lot of political capital was spent on an issue that was factually dubious at best, thousands of right-wingers died because of it and little was achieved.

IMO it's more nuanced than this. The issues involved are very complicated.

Tens of thousands of people work with vaccine research and safety and they are spread across a tripple digit number of countries. No conspiracy that size has a snowball's chance in hell to survive.

Right-wingers have good reason to distrust authorities. There are thousands of medical experts who advocate for transgenderism, for example, or who work in the psychiatry industry cooking up bogus disorders like "toxic masculinity".

Of course you could say that the field of vaccine research is a lot more solid and more difficult to politicize than other fields. But when many of the most vocal proponents of vaccines are people who said they wanted you dead just a few weeks earlier, it's hard to shift gears and change heuristics.

The greater failure for the right was the lack of debate or discussion before coming to a position on COVID-related issues. Most positions were just kneejerk reactions against what the left was doing. Fortunately, many of these reactions ended up being right: lockdowns really were a way to disadvantage small businesses in favor of corporations, and the media really was pushing double-standards in calling right-wing gatherings "superspreader events" while praising left-wing protests.

However, other reactions were very wrong, such as treating covid like it didn't exist at all.

Ultimately this comes from the right's disorganization and (unintentionally) decentralized nature. The sad truth is that this sub is one of the few places where rightists can actually debate and think critically, unlike many of the echo chambers where one must take a hardline in one direction or the other.