The other strains were not covered because they were not common.
Now they are.
Which means some new strain will become common. Is there any data on how quickly/easily new strains show up? I assume it's not as fast as cold/flu, but if it is people will need a vaccine yearly, and that's not realistic.
Now they are.
Which means some new strain will become common. Is there any data on how quickly/easily new strains show up? I assume it's not as fast as cold/flu, but if it is people will need a vaccine yearly, and that's not realistic.