President Trump's announcement on Friday that he tested positive for the coronavirus has raised many questions about what the infection could mean for the health of the leading American politician.
In a statement, the president's doctor said Mr. Trump, who is 74 years old, was "healthy" but did not say whether he had any symptoms. He said the president will remain isolated in the White House for the time being.
Here's what we know about how the virus can affect people with its general profile.
Older men are at greater risk of getting seriously ill.
According to an analysis by the Chinese Center for Disease Control and Prevention, older men are up to twice as likely to die from Covid-19, the disease caused by the coronavirus, than women of the same age. Another study published in Nature in August found that this was because men produce a weaker immune response than women.
The potential for hospitalization increases after age 50, said Raina MacIntyre, who leads the biosecurity program at the University of New South Wales' Kirby Institute in Sydney, Australia.
Obesity is another risk factor for dying, especially in men, according to an analysis of thousands of patients treated in a Southern California health system.
"If you don't know anything about Donald Trump and just know that he is a man over 70 and appears to be instantly overweight, you can say he is at risk," said Michael Baker. Professor in the Department of Global Health at the University of Otago, Wellington, advisor to the New Zealand government.
Still, many people at his age have recovered from Covid-19.
Although the risk of developing serious illness from Covid-19 increases with age, most people who become infected will get well quickly with minimal symptoms.
"The good news is that even people with a range of risk factors do well on average," said Professor Baker. "Only a minority have illness and serious consequences."
"Many people his age who get Covid are actually doing well," said Benjamin Cowling, director of the epidemiology and biostatistics department at the University of Hong Kong.
The outcome could be complicated if Mr Trump has certain underlying health conditions that researchers largely agree that pose a risk for serious illness.
Mr Trump, White House officials and his doctor have been claiming for the past few months that the president is in good health. But Mr. Trump loves cheeseburgers and doesn't exercise much other than playing golf. In June, Mr. Trump's doctor said the president weighed 244 pounds, which makes him easily obese.
"Unless he has diabetes, high blood pressure, or long-term illness, the outcome is unlikely to be severe," said David Hui, director of the Stanley Ho Center for Emerging Infectious Diseases at the University of Hong Kong in China.
It's hard to say how long it would take for Mr. Trump to recover.
Experts agree that the next week will be crucial in the course of Mr Trump's illness.
If Mr Trump does not develop symptoms, antibodies will appear 10 days after the onset of the disease and he will recover, according to Dr. Hui from the Chinese University of Hong Kong.
Dr. Anthony Fauci, director of the National Institute for Allergies and Infectious Diseases, said "the good news about Covid-19" is that around 40 percent of those infected never develop symptoms.
Current estimates suggest that if symptoms did occur, they could do so as early as two days or up to 14 days after exposure to the virus.
If Mr. Trump develops mild symptoms such as a cough, fever, or shortness of breath, it may take a week for him to recover. A serious illness that could mean the development of lung lesions and pneumonia could require hospitalization, possible ventilation, and months of treatment.
"They couldn't set a specific time," said Dominic Dwyer, a medical virologist at the University of Sydney. "Regardless of what you think about politics, you wouldn't want anyone to do that."
Treatment depends on the severity of his illness.
Experts agree that Mr Trump's treatment regimen will depend on whether he develops symptoms in the days ahead.
As long as he has no or limited symptoms, it would be enough to maintain a comfortable environment where he can be isolated for 14 days and regularly examined by doctors.
There is of course no cure for Covid-19 yet. However, if Mr Trump develops pneumonia, respiratory failure, and other signs of more serious illness, there are a number of treatments available to him that have been widely used by doctors and nurses.
Remdesivir, an antiviral drug used to treat hepatitis and a common respiratory virus, has been shown to be useful in treating critically ill patients. According to researchers at Oxford University, a steroid called dexamethasone has also reduced mortality in such patients.
Elsie Chen contributed to the coverage.