Pfizer Inc. is set to dominate the $20 billion market for COVID-19 pills next year as richer nations rush to purchase supplies, while less affluent countries will have to wait until early 2023 for generic-drug companies to produce large quantities, an analysis shows.

Pfizer, already pulling in huge profits from its COVID-19 vaccine, is expected to reap about $17 billion from sales of its experimental therapy Paxlovid in 2022, according to Airfinity Ltd. Merck & Co.¡¯s molnupiravir will see about $2.5 billion in revenue next year, the London-based data company said.

Demand for the medications is poised to outpace supply as COVID-19 spreads around the globe and scientists question how well vaccines and antibody treatments will hold up against omicron and other variants that could arise. Rich countries¡¯ purchases have fueled concerns that, after struggling to obtain vaccines, the less wealthy could be left behind once again, despite licensing agreements to widen availability of the drugs.