"It’s important to get some perspective on this decision. The Oxford/AZ vaccine saved millions of lives. It was produced at a time when we knew little about the SARS-CoV-2 virus and were in desperate need of a vaccine to prevent severe disease. This vaccine was crucial to the global fight against COVID-19.

Updating this vaccine technology to cover new Covid-19 virus variants is difficult compared to mRNA vaccines which can be more rapidly modified. As the covid virus continues to mutate, the mRNA vaccine platform offers more flexibility. The decision to withdraw the AZ vaccine is probably mainly due to the cost and complexities of generating updated vaccines to new virus variants. The rare but serious thrombotic side effects of the vaccine must also have been a consideration."