The World Health Organization has called on people to avoid the "Three Cs," which stand for three settings where the COVID-19 virus spreads more easily.

In a Facebook message, the WHO writes that the Three Cs represent "Crowded places," "Close-contact settings," and "Confined and enclosed spaces."

It defines "Crowded places" as those with many people nearby, "Close-contact settings" as places especially where people have close-range conversations, and "Confined and enclosed spaces" as sites with poor ventilation.

The message recognizes that the risk is higher in places where the three factors overlap. It notes, "Even as restrictions are lifted, consider where you are going."

The message sets out five things that people should do.

They are "Avoid crowded places and limit time in enclosed spaces," "Maintain at least 1 meter distance from others," "When possible, open windows and doors for ventilation," "Keep hands clean and cover coughs and sneezes," and "Wear a mask if requested or if physical distancing is not possible."

The message adds, "If you are unwell, stay home unless to seek urgent medical care."