I'm not "very worried" but we should all be somewhat worried when this stuff happens because that would suck so much to have a successful vaccine, only for it to be ineffective by a mutation. I am not looking at media sensationalism for this. This is not just me saying "OH LOOK ANOTHER VARIANT!!!" I actually read scientific information. After not knowing much about the UK strain, and not understanding, I have been paying closer attention these days to what is being studied.
The UK variant was concerning because it is much more virulent than the original strain, that's bad news for already overwhelmed hospitals.
This one is concerning because it contains the most changes to the spike protein, it is showing an interesting pattern when it comes to reinfection, and its possible that this variant is closest to escaping immunity. Many European countries are closing off travel from LATAM, not just the UK. Research is still being conducted on it, but it seems to have epidemiologists worried, many focused on the Spike protein.
Here are just a few good threads from professionals that you can all read about regarding the Brazil strain. Its easy to say "nah I'm not going to look at that. The media is just sensationalizing it. Theres always going to be a mutation." Its true that there will always be a mutation, but we have a rare opportunity to educate ourselves whilst it is occurring right before our eyes. Its actually very interesting stuff if you take the time to read about it. (also take a closer look at the sequencing images many have posted)