when is covid contagious

COVID-19 is contagious starting from about 1 to 2 days before symptoms appear or before a positive test if asymptomatic. The contagion period generally lasts until symptoms fully resolve, which can be up to 10 days, but some people, especially those severely ill or with weakened immune systems, can be contagious longer. The highest contagiousness tends to be around the onset of symptoms and during the first 5 days of illness, with viral shedding gradually decreasing afterward. Even people who do not show symptoms can spread the virus during this pre-symptomatic and asymptomatic phase.