Panic now!
J/K. I had to reschedule my Germany trip 4x! I was finally able to go, then just barely made it back before they had covid wave #5. I feel like I got sick of panicking and just opted for rebooking perpetually for around 18 months, and making sure everything was refundable or rebookable.
In March of 2020 (my trip was scheduled for the end of March) I knew it was going to be bad as soon as Italy saw people getting very sick and it beginning to spread. Mind you, I was still down for going and wearing a mask and spraying everything with bleach until of course the USA and Europe said "NO TRAVEL." Then I had my 7 hour + Lufthansa hold on the phone (a record!). I rescheduled for October hoping people would be logical and stay home and it would be mostly tampered down like Korea or China within 6 months.. (#joke).
By about mid summer I knew we were hosed and we couldn't go in October. Europe was not opening, the supposed "vaccines by fall" never really happened and people were getting sick here in the states still. Fall looked like it was going to be bad everywhere.
Fall- ok its bad everywhere and with no vaccines in sight and everything still closed. I moved the trip again to April of 2020 hoping things wouldn't be bad and since I could get vaccinated early perhaps our regulations (and Europes) would be fixed. (#joke#2). Got vaccinated in Jan/Feb since my job allowed it....
But yes no dice on getting into Europe with having to quarantine and that not changing yet. Then there was "Delta" --- realized we couldn't go around March and rescheduled for October.
Europe opened in the summer so I was very hopeful about going in the fall, but still cautious and looking at their covid rates and the regulations, there was no way we could go if things changed to having to be quarantined or there was lockdowns that looked "imminent" . With museums closed and no ability to eat at a restaurant (or even outside of one) there is zero reason to go.
I had to basically watch the German news sites (and this forum) for the whole month of August and September. When Germany only changed regulations for the un-vaxxed as it was fine for vaxxed to go, and no lockdowns seemed impending (at the time) my friend and I decided to pull the trigger, but we literally were watching the news up to 1 week before our flight to see if we needed to change it. And well, we went.. We were extremely precautious, had a rental car, bleached and medical-grade cleaned everything in our rooms upon entry, wore new masks everyday, gloves, ate outside as much as possible. Both of us were fine and didn't catch the covid. BUT--- if things were like they were now in Germany there is no way either of us would risk going since it seems lockdown is probably pending and there isn't a way to really enjoy eating if you have to be indoors and constantly staring at everyone who has a dry cough. That is the big "if" question.
Granted, knowing if lockdown is "pending" or what authorities will do is anyone's guess, but if it looks probable, well it most likely will happen and you don't want to be trapped in your hotel, bored to tears and unable to see what you came to see. Or worse yet, have to quarantine for 14 days or however long at your own expense before coming, or extra worse yet, while you are in country! No one wants that. My friend and I are younger (under 40) and healthy + vaccinated. There is only so much one can do though.
To me the panic moment is when you see nations closing borders- which is what they are doing with omnicron. Depending when your trip is scheduled I would seriously consider re-booking. For me if I had a trip in the spring I wouldn't pull the trigger just quite yet-- I'd wait a month to see if this is the nasty bug people speculate it is, or if it ends up being milder. If it was this December or January I would cancel. No question.