Common truisms I've heard (especially in Feb-March, but still occasionally these days) is that "worry and panic is worse than the disease itself" or that "the most important messaging during a pandemic is "don't panic.""
It's relatively easy for me to find examples of significant potential harms of excess panic (eg, anxiety, agoraphobia and other psychological issues, fear of going to a hospital for other emergencies, racially motivated or otherwise outgroup violence).
But when I look at historical examples of actions during pandemics, it was hard to find *any* examples of lots of additional people dying or a pandemic otherwise made much worse by excess panic, while it was comparatively common to find examples of pandemics made much worse by insufficient worry (NunoSempere has a list here).
If there are historians or history buffs among this group, I'd love to see people provide counterexamples illustrating when excess panic makes pandemics much worse.
Practically all previous pandemics were far enough back in history that their applicability is unclear. I think it's unfair to discount your example because of that, because every other positive or negative example can be discounted the same way.