Merck & Co.’s blockbuster vaccine Gardasil has had a roller-coaster ride in China. A post-Covid surge in demand for the cancer-preventing shot quickly deflated last year, to the point the US pharmaceutical giant made the call earlier this week to halt shipments.

Shares of Merck are sliding in early trading after the drugmaker surprised Wall Street with a lower-than-expected 2025 sales forecast due partly to a pause in shipments of one of its top-selling products to China.

Merck said on Tuesday it would not ship its HPV vaccine Gardasil in China until at least the middle of this year due to weak discretionary spending, a move that dented its full-year forecast and sent shares tumbling over 8% in premarket trading.