The World Health Organization says the COVID-19 outbreak has become a pandemic.

Its director general says the virus that causes the respiratory illness can still be fought but some countries are struggling with a lack of resources and some with a lack of resolve.

Media briefing on #COVID19 with @DrTedros. #coronavirus https://t.co/aPFXT3ex5y

— World Health Organization (WHO) (@WHO) March 11, 2020

For most, the coronavirus causes only mild or moderate symptoms, such as fever and cough. But for a few, especially older adults and people with existing health problems, it can cause more severe illnesses, including pneumonia. More than 121,000 people have been infected worldwide and over 4,300 have died.

But the vast majority of people recover. According to the World Health Organization, people with mild illness recover in about two weeks, while those with more severe illness may take three to six weeks to recover.