After racing to build capacity and meet once seemingly insatiable orders for COVID-19 shots, the global vaccine industry is facing waning demand as many late-to-market producers fight over a slowing market.

The trend is poised to rein in the blockbuster sales that global pharmaceutical giants from Pfizer Inc. to AstraZeneca PLC saw at the peak of the pandemic. It also stands to create new problems for local manufacturers from India to Indonesia that built mammoth capacity to make shots but are now grappling with excess supply.

Even as boosters are likely to keep demand alive for COVID-19 inoculations worldwide, the desperate shortages that existed for much of last year have waned. Instead, in a dramatic reversal, the possibility of a global glut is now looking more likely.