and Moderna are facing a "COVID cliff"Those firms, along with others like Gilead Sciences, AstraZeneca, and Merckare estimated to have earned $100 billion over the last two years from COVID vaccines and treatmentsAnalysts expect those sales could fall by nearly two-thirds this year Pfizer brought in $56 billion in revenue in 2022 fromits vaccine with BioNTech and antiviral drug PaxlovidThe company expects that to drop to $21.5 billion in 2023Moderna pulled in around $18.4 billion in2022 from its messenger RNA COVID vaccineIt expects revenue to drop to around $7 billion in 2023Other companies like Merck and Eli Lilly have seen a more modest impact from their COVID businessesQuote from David Ricks, Eli Lilly CEO:"We did fine with COVID. We made a little bit of money with it. What we did with that was we mostly reinvested it in R&D (Research and Development), and last year was a record R&D spending year for the company."