The World Health Organization says that the nature of the pandemic is now, increasingly, being driven by young people.
Regional director Takeshi Kasai explains.
"The epidemic is changing. People in their 20s, 30s and 40s are increasingly driving its spread. Many are unaware they're infected with very mild symptoms or none at all. This can result in them unknowingly passing on the virus to others. This increases the risk of spillovers to the most vulnerable: the elderly, the sick, people in long-term care, people who live in densely-populated urban areas, and under-served rural areas."
The news will be concerning for countries globally, who on the one hand want to encourage young people to visit for tourism - whilst trying to protect the health of their own citizens.
Many are clearly still nervous about letting people in from overseas.
For example on Tuesday (August 18), Dubai said it still requires foreign residents who are overseas to obtain permission before returning.
And in Europe many countries have started restricting tourism travel in recent weeks, now for the second time since the pandemic started.
According to a Reuters tally, COVID-19 has killed more than 770,000 people and infected nearly 22 million people worldwide.