TOKYO: About 80 pct of coronavirus patients from the virus-hit Diamond Princess cruise ship showed no or mild symptoms, according to a report compiled by the Japanese Self-Defense Forces Central Hospital.

The Tokyo hospital accepted patients who tested positive for the virus in their polymerase chain reaction, or PCR, checks on the ship, and gave an analysis of 104 people who agreed to cooperate for the report and its release.

The report is believed to be one of the largest analyses of coronavirus-caused symptoms compiled in Japan, according to the Defense Ministry. The report was posted on the hospital's website for medical workers.

The proportions of patients who showed no symptoms and mild symptoms when they were hospitalized were 40 pct, respectively, while the remaining 20 pct showed serious symptoms, according to the report.

But the report added that computed tomography, or CT, scans of the lungs of the patients with no or mild symptoms showed that half of them had apparent abnormalities caused by the virus.

About two-thirds of the patients with apparent lung abnormalities recovered without changes in symptoms, while the conditions of the remaining one-third got worse.

There were cases in which patients showed coronavirus-like symptoms in CT scans of lungs but tested negative for the virus in PCR checks, the report said.

"The results may be showing the effectiveness of CT scans at initial diagnoses," a medical expert at the ministry said.

The most common symptom seen when the patients were hospitalized was a fever, followed by coughing.

The average age of the patients was 68, and 48 pct of them had underlying diseases, with the largest proportion of them high blood pressure.

Jiji Press