Your sinuses being cold contributes to reduced immunity to any airborne pathogens. So why do we tend to get specifically colds (and flu) when it’s cold out? It is likely because we are inside, in enclosed spaces, much longer and more frequently. Colds will spread around schools and workplaces just fine without cool weather.
Wear a mask.
We would not be about to store data. Any changes to digital (or analogue) data would be reverted. So even if we all collectively try to ignore the fact that time is repeating and live as normally as possible, we can’t have a society that keeps track of things in anything other than human memory. Advanced accounting, modern engineering, and scientific research would be impossible.
Somebody mentioned that the scenario doesn’t make sense because of time zones. Consider this scenario: Things are only reset locally at midnight. If you pass something across a time zone boundary, it doesn’t get reset until midnight in the new time zone. You could theoretically carry forward information or important objects indefinitely if you swap them before midnight in your time zone and then swap them back before midnight in the holding time zone. Things for which this cannot be done for cannot be preserved from being reset.