One is that infectious diseases remain a very severe burden on humanity. They haven't been solved. In the United States, we sometimes don't pay that much attention to infectious disease because we're a relatively rich country, and we don't often see the impact. But, globally speaking, the burden is still immense.
The other take-home message is that new threats are always emerging, so we have to prepare. When COVID happened, it wasn't particularly surprising to me, because if you study history, you know some new infectious disease emerges every few years. HIV only really emerged in the 1980s. SARS-CoV-1 caused a serious outbreak in 2003. Before the COVID pandemic, there was a flu pandemic in 2009 that everyone was worried about.