Did later policy changes allow AstraZeneca only for certain age groups?

The short version: yes, multiple countries restricted AstraZeneca to older age groups after regulators confirmed the VITT risk was concentrated in younger adults.

The evidence from the retrieval is direct. A Scottish case-crossover study found that in people under 60, the rate of primary acute cerebral venous thrombosis within 28 days of ChAdOx1 vaccination was 7 per million doses (95% credible interval 3.1 to 11.9), based on 8 events [1]. The same study reported a rate ratio of 3.2 (95% credible interval 1.1 to 9.5) for CVT in the first 14 days after vaccination compared to later time windows [1]. A global analysis of 552 CVST cases after COVID-19 vaccination found a mean age of 44, with a 2.25-to-1 female-to-male ratio [3]. The incidence data from multiple countries shows the same pattern: Norway reported 1 VITT case per 26,500 doses, the UK about 1 per 70,000, and Germany about 1 per 90,800 [2]. The syndrome struck young and middle-aged adults disproportionately.

The policy response followed the evidence. By mid-2021, the UK, Germany, France, Canada, Australia, and other countries restricted AstraZeneca to people over a certain age threshold, typically 50, 55, or 60 years, while offering mRNA vaccines to younger adults. The rationale was explicit: the VITT risk was higher in younger people, while the risk of severe COVID-19 was lower in that group, so the risk-benefit calculation shifted. The retrieval does not contain the specific regulatory documents, but the age-specific incidence data in the evidence directly supports the policy logic.

My call: yes, later policy changes restricted AstraZeneca to older age groups, and the evidence supports that the restriction was based on a real age-dependent risk of VITT. Confidence: high.