There is one, but it's not necessarily worth it because the original is "good enough". Also, future strains might be more like the 2020 version again; no reason they wouldn't be.
A better upgrade will be when it's a nasal spray. That's more effective at blocking transmission, and some people just don't like needles.
A better upgrade will be when it's a nasal spray. That's more effective at blocking transmission, and some people just don't like needles.