This year, Pfizer expects to bring in $36 billion from worldwide sales of its COVID-19 vaccine. That would shatter the previous record in annual sales for a single pharmaceutical product - about $20 billion for the anti-inflammatory drug Humira - and make the Pfizer vaccine the bestselling pharmaceutical product ever. Moderna will deliver fewer doses but is still expecting up to $18 billion in sales for the year for its COVID-19 vaccine. Humira, has been ... churning out tens of billions of dollars a year for multiple years on end. And it's not entirely clear that the mRNA vaccines will do that. Just because Pfizer and Moderna are selling billions of doses now doesn't mean that will last forever. The vaccines could work so well they eliminate the need for further boosters, though it's also possible COVID shots could become routine, like flu shots. The uncertainty puts a premium on maximizing sales now. Any vaccine manufacturer is going to realize that there's a risk that they're going to have a very short lifecycle. Moderna got a lot of government funding, offsetting costs and minimizing risks. But the COVID-19 vaccine is its only product on the market. Pfizer, on the other hand, didn't accept early government investment and took on a lot of those upfront costs itself. But it has dozens of other products in its portfolio that it makes and will continue to make once the pandemic ends.