In its latest update, the US Centers for Disease Control and Prevention (CDC) has said that Covid-19 transmission can occur in poorly ventilated and enclosed spaces.

In a statement released on Monday, the CDC said: "Today's update acknowledges the existence of some published reports showing limited, uncommon circumstances where people with Covid-19 infected others who were more than 6 feet away or shortly after the positive person left an area.

"In these instances, transmission occurred in poorly ventilated and enclosed spaces that often involved activities that caused heavier breathing, like singing or exercise.

"Such environments and activities may contribute to the build-up of virus-carrying particles."

In the statement, the agency further said that the latest update does not change its recommendations for protest against the virus by wearing masks, staying six feet apart and washing hands.

The overall number of coronavirus cases in the US as of Tuesday has increased to 7,455,184, while the death toll stood at 210,155, according to the Johns Hopkins University.

The country is currently the worst-hit in the world with the highest number of infections and fatalities.