Depends on your definition of culture, tbh. If you think of Marvel superhero movies as "culture" then for sure.If America isn't the center of the world, why can't you stop talking about America?
I don't think the effectiveness of a nation's response to COVID-19 has any bearing on it's global relevance. On the contrary, one of the big reasons some countries have been able to do so well is precisely because they are very much NOT at the center of the world (Australia and New Zealand for instance).
No country in the world is talked about as much as America, no country in the world has their culture consumed and copied as much as America, etc. I just don't see what country you could put above America in terms of global relevance if you're even a quarter honest.
I do think this crisis has affected the US's global relevance negatively, but not extremely so, I would argue that having a braindead sociopath with an isolationist agenda as their president has been far more harmful. I mean, he would be ridiculous as head of state even in a banana republic.