There are flu vaccines every year. But they are not targeted for one strain ... they are developed many months in advanced based on a guess of what variants might be most common. Sometimes they guess right, often they do not. Most people don't get them.

On the other hand, in 2017-2018, vanishingly few people were wearing masks, or social distancing, people weren't avoiding (or governments prohibiting) high density gatherings.

Again, you are comparing apples and oranges.