New York: Many studies earlier showed that in the first few months after their COVID-19 hospital stay, patients face a high risk of ongoing health problems, trips back to the hospital, and even death, but now the researchers have found that the first week and a half maybe especially dangerous.

COVID-19 patients had a 40 per cent to 60 per cent higher risk of ending up back in the hospital or dying in the first 10 days, compared with similar patients treated at the same hospitals during the same months for heart failure or pneumonia.

By the end of 60 days, the COVID-19 patients' overall risk of readmission or death was lower than that for the other two serious conditions, the findings, published in the journal JAMA, reported.

Even so, in the first two months, nine per cent of the COVID-19 patients, who survived hospitalization had died, and almost 20 per cent had suffered a setback that sent them back to the hospital.

That's on top of the 18.5 per cent who had died during their hospitalization.

"By comparing COVID-19 patients' long-term outcomes with those of other seriously ill patients, we see a pattern of even greater-than-usual risk right in the first one to two weeks, which can be a risky period for anyone," said the study author from the University of Michigan in the US.

The most common reasons listed for rehospitalization were COVID-19, cited in 30 per cent of patients, and sepsis seen in 8.5 per cent. More than 22 per cent of the readmitted veterans went to the intensive care unit.

"Unfortunately, this is yet more evidence that COVID-19 is not 'one and done.' For many patients, COVID-19 seems to set off cascades of problems that are every bit as serious as those we see in other diseases," the team wrote.

The research team hopes to continue to study new data from Veterans Affairs (VA) and non-VA hospitals as it becomes available and to compare COVID-19 post-hospital outcomes with those for other serious conditions.

"Comparisons with patients hospitalized for influenza and other viral illnesses would be important to study, given the widespread false claims that COVID-19 is just a minor illness," they noted.