Late on Remicade infusion...how dangerous?

The answer really depends on what your current remicade concentration is within your blood. If you have a high enough remi concentration now then it's possible to get by an extra week or possibly two without seeing symptoms return. It's also possible you don't have enough remi and could start seeing symptoms return, so be mindful and watch for symptoms. Everyone uses remi protein at a different rate and also has a different rate of flushing protein from their blood (some are faster or slower than others). So, it's not easy to pin exactly how long each individual will have enough.

Antibody development is possible but I'd say a small risk. You're likely talking a 10 week infusion schedule instead of a 8 (I'd assume at the normal schedule). I've seen 10 weeks as a acceptable remicade interval before (4, 6, 8, and 10 week intervals).

Good luck, hopefully there's no troubles. It's tough when switching insurance, unfortunately they determine approval and availability. You can always get some rowasa on hand, just in case or to take as a precaution.

Generally, antibody risks are highest when first starting remicade as that's when your immune system is first exposed to remicade proteins and when it would then attempt to stop a foreign invader (if remi was determined to be one). Generally that's the way the immune system responds (if you think infections and flus, then there's a strong early response). There's always risk in everything though.