Pfizer and BioNTech has said that late-stage trial data shows COVID-19 vaccine is more than 90% effective in preventing infection. A sign to start getting invested in Pfizer?

It's a sign you are a FOMO investor. If you did your research, you would have bought in when Pfizer was more fairly valued. You don't go in when everyone already knows the news and are extremely greedy, because when everyone already knows the news, its already too late and you are just risking higher downside.