Photo/Illutration The novel coronavirus seen through an electron microscope (Provided by the U.S. National Institute of Allergy and Infectious Diseases)

OKAYAMA--More than half of patients who visited Okayama University Hospital’s COVID-19 aftercare (CAC) outpatient clinic continued follow-up treatments for 180 days or more, a group of researchers said.

The team, led by Fumio Otsuka, an OUH professor of internal medicine, also said women outnumbered men among patients with the long follow-up periods.

“Long COVID, once contracted, may be slow to go away,” Otsuka said. “People tend to believe the coronavirus pandemic is over, but they should not forget to watch out for COVID infections to the best extent possible.”

OUH in February 2021 became the second general hospital in Japan to open a CAC outpatient clinic.

The OUH CAC has since examined more than 1,200 patients suffering from post-COVID conditions while studying changes in coronavirus variants and in long COVID symptoms.

In the latest study, the research team scrutinized CAC outpatients infected with the Omicron variant and the correlation between their long COVID symptoms and the duration of their follow-up treatments.

Of the 774 long COVID outpatients infected with the Omicron variant who visited the CAC between February 2022 and October 2024, 370 were classified in the “early recovery group,” with follow-up periods of fewer than 180 days.

The 404 others, or 52 percent of the total, were in the “persistent-symptom group,” with follow-up periods of 180 days or longer. Some continued visiting the clinic for two or three years.

The team found no statistically significant differences in age and number of vaccinations received between the early recovery group and the persistent-symptom group.

Women accounted for about 60 percent in the persistent-symptom group. They also complained more about fatigue, insomnia, memory disturbance and paresthesia (numbness) than those in the early recovery group, the researchers said.

NEW NIMBUS DANGER

Otsuka also warned the public against the Nimbus variant, which was derived from the Omicron strain.

“Nimbus cases are on the rise in Okayama Prefecture,” he said. “You should remain on the alert.

Otsuka said the number of COVID infection cases per medical institution in Okayama Prefecture is larger than those in neighboring Hiroshima and Hyogo prefectures and exceeds the national average.”

“Nimbus is believed to be characterized by a severely sore throat, but fever and cough symptoms, rather than a sore throat, prevail in certain Nimbus patients,” he said. “You are advised to take an antigen test, sooner rather than later, when you have fever, sore throat, cough or other symptoms of a cold.”

Otsuka explained it takes two or three months for long COVID symptoms to emerge.

“You should start consulting your regular doctor if, for example, you were infected with COVID-19 around the Bon holidays (in mid-August) and are still suffering from fatigue or other symptoms around October,” the professor said.

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