their efficacy against all symptomatic cases of the disease found in trials has been lower, ranging between 66% and 95%. Some of that range is down to intrinsic differences between the vaccines.

Source: The Economist

What does the bold text mean?

It clearly makes no sense if I understand "intrinsic differences between the vaccines" as the number of range.

1 Answer 1


"Down to" in this sentence is used to mean "a result of". See definition 12 of "down" here, where it's marked as chiefly British usage.

So the sentence means:

Some of the variance between 66% and 95% is caused by differences in the vaccines themselves.

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