It's sick season. Here's how to protect yourself from norovirus, COVID-19, flu and RSV

In the winter months, it seems few are safe from some kind of illness — flu, COVID-19, norovirus, colds. While many of the germs that cause this misery can circulate throughout the year, scientists think that the winter surge of flu and cold activity may be because we spend more time indoors and the cold, dry air may weaken our defenses. How do I know whether I have the cold, the flu, COVID-19 or something else?