[kevincox]

Yes what is "required" is controversial. What I meant to say is that they could have chosen to go for a yes/no type of verdict but instead they chose to let the reader decide if they consider the protection acceptable. Both decisions have pros and cons.

[distances]

What's "acceptable" can vary by country. They couldn't have done this with the acceptance bit only.

[lxgr]

Additionally, the situation is constantly changing. A vaccine effective today might be considered insufficient tomorrow, e.g. due to mutations, new studies etc.