The supply issues added to the firm's troubles, with some countries including Denmark, Norway and Iceland suspending use of its shot over concerns over side effects such as blood clots.
"AstraZeneca is disappointed to announce a shortfall in planned COVID-19 vaccine shipments to EU despite working tirelessly to accelerate supply," it said in a statement.
The Sinovac shipment arrived with huge fanfare at Bangkok's airport, with a Chinese embassy official vowing that the vaccine export showed the "strengthened relations between China and Thailand".
The EU has so far approved three vaccines -- Pfizer-BioNTech, Moderna and AstraZeneca-Oxford. Three other vaccines are under "rolling review" by the Amsterdam-based EMA -- Novavax, CureVac and Russia's Sputnik.
Denmark, Norway and Iceland on Thursday temporarily suspended the use of AstraZeneca's Covid-19 vaccine over concerns about patients developing post-jab blood clots.
Denmark however suspended the use of all of its AstraZeneca supply, as did Iceland and Norway in subsequent announcements on Thursday citing similar concerns.
Tecentriq initially won accelerated FDA approval in 2016 for people previously treated for the most common form of bladder cancer, but was required to gather follow-up data in order to win regular approval.