Re-training regression model on covid data
Your previous model won't be useful. In my opinion, you can not use it to make predictions in Covid Pandemic, since all bookings have had a huge decrease.
I would recommend build a new model with only data of the Covid Pandemic time. Then, you will have a more accurate model for these times. The only problem if you have less historical data, but for sure, is better have less data but useful, than huge dataset that is not representative of current times.
Be aware that you can probably add some useful features in this new model, for example, number of deaths for Covid per day of the country. For sure this feature will help you because if you have a huge number of deaths per day, probably you will have less booking, otherwise, if there are less deaths per day, there should be more bookings.