The announcement that Donald Trump has tested positive for the Sars-Cov-2 virus has rocked the US barely a month out from the presidential election. Much will now depend on how his condition evolves.
A striking feature of Covid-19 has been its unpredictability. Infection can cause symptoms ranging from the pneumonia that characterised the disease when it emerged in China, to problems with the heart and circulation, or the brain and nervous system. In other cases, people infected with the virus — including those in their seventies such as Mr Trump — can recover without suffering any symptoms, or nothing worse than a temporary loss of smell and taste.
Mr Trump is 74. On average, someone in their mid-seventies who tests positive for coronavirus has about a 20 per cent chance of requiring hospitalisation and a 5 per cent chance of dying from Covid-19 in countries with good medical systems.
Other factors, including weight and general health, can also affect the course of the virus.
“The president’s profile would classify him as vulnerable,” said Michael Head, senior research fellow in global health at Southampton university in the UK. “He is aged 74 and reportedly overweight. Many people in their seventies will also have further comorbidities that increase the risks of a more severe illness.”
Mr Trump will receive the best care available, which will improve his prospects. Sean Conley, the president’s physician, said he expected Mr Trump “to continue carrying out his duties without disruption while recovering”.
That optimistic forecast may turn out to be justified but other experts said the future effects of the virus were difficult to predict so soon after a positive test.
“With a single positive result, it is difficult to say exactly where he is in his infection and when he was infected,” said Julian Tang, consultant virologist at Leicester Royal Infirmary. If symptoms developed, most people remained well enough to stay outside hospital during the first five to seven days of the illness, said Dr Tang. “Thereafter, it may become more serious, requiring hospitalisation — or they start to recover by themselves.”
In April, UK prime minister Boris Johnson was admitted to St Thomas’ Hospital in London 10 days after testing positive for the virus. He spent three days in intensive care.
Independent medical experts were reluctant to speculate about the president’s prognosis.
“Donald Trump has some risk factors such as being male, older and overweight, but if he has no chronic conditions and is reasonably active then these may offset or attenuate his risks so that he may recover swiftly from the infection,” said Naveed Sattar, professor of medicine at the University of Glasgow. “The risk of serious disease and death depends on many factors, and it is not so simple as to make inferences from one or two alone.”
Trish Greenhalgh, professor of primary healthcare at the University of Oxford, said it would be important to know when Mr Trump was infected to assess “the likelihood that he could have infected Mr Biden and others during Tuesday’s presidential debate”.
“There is strong evidence from many sources that the Sars-Cov-2 virus is transmitted via shared air as well as by droplets and direct contact,” she said. “People in the same room, even if more than two metres apart, are at risk because eventually the airborne virus reaches all parts of the room.”