Gardasil (Merck) is expected to face US follow-on vaccine competition from 2028. Key patents expire around 2028. Sales fell 39% in 2025 on weaker China demand.
Gardasil's US exclusivity date is based on patent-expiry estimate. It is estimated from patent expiry rather than a fixed entry date, so it may move as patents are challenged or extended. It is a vaccine. Vaccines are hard to copy, so competition after patents expire usually arrives slowly.
Gardasil is 8% of Merck's 2025 revenue ($5.2B of $65.0B). With Keytruda, the drugs tracked here add up to 57% of Merck's revenue losing US exclusivity by 2028.
Bars show each company's tracked drugs as a share of its total 2025 revenue. Gardasil is highlighted.