COVID aftereffects more common in women, possibly linked to immune system: Japan researcher

TOKYO -- Women are more likely to suffer from COVID-19 aftereffects, especially coughing, hair loss and taste disorders, a study by Japanese researchers has revealed.

One factor attributed to these results is that men and women have different immune systems, such as "T cells" that eliminate viruses.

Hideki Ueno, a professor of human immunology at Kyoto University, has been conducting research based on the hypothesis that "when T cells produced in the immune response system following viral infection deviate from normal -- either too many or too few -- these aftereffects appear."

Ueno examined the blood of about 70 patients who were infected with the COVID-19 virus, including the delta variant that peaked last summer, and who were suffering from aftereffects. The results showed that these ailments tended to vary according to the amount and type of T cells that were produced to eliminate the coronavirus and were involved in immune acquisition.

For example, in women with strong symptoms of breathlessness and heart pounding, the number of both types of T cells, those that eliminate viruses and those that suppress excessive immune activity, were high. In short, it was thought that the immune system was "out of control," and that this was what caused the symptoms.

In men, such reactions were less common, and Ueno said, "Women have always been more prone to autoimmune diseases such as rheumatoid arthritis than men. The pattern of immune response in women may be related to their susceptibility to autoimmune diseases and the aftereffects of the coronavirus."

Meanwhile, in men, there is a possibility that a different mechanism may lead to the aftereffects. Those with stronger symptoms of poor concentration and depression tended to have lower overall T-cell counts.

Ueno speculated, "It is believed that pieces of the virus are scattered in various organs as a result of viral infection, but if the number of T cells is low, these pieces cannot be removed from the body, and the symptoms may linger for a long time."

However, there is a possibility that the immune response will be different in patients suffering from the aftereffects of the omicron variant that is currently prevalent. Ueno hopes to have his data verified by researchers around the world, leading to the elucidation of the mechanism of the aftereffects and the development of a treatment focusing on T cells.

The difference in aftereffects between men and women was also confirmed in a large-scale survey conducted by a health ministry research team. The team conducted a questionnaire on aftereffects among approximately 1,000 patients aged 18 or older who were infected with the COVID-19 virus and hospitalized for treatment between January 2020 and February 2021. The survey also followed them for three months, six months, and one year after diagnosis.

The results showed that 46.3% of all respondents had one or more symptoms three months after diagnosis, and 40.5% six months later. Although the number decreased over time, 33% still had some symptoms after one year.

Looking at the results by gender, 43.5% of men and 51.2% of women had symptoms three months after diagnosis. The most common symptoms among women were coughing, hair loss, headaches, and smell and taste dysfunctions. The health ministry concluded that "women clearly had a higher percentage of aftereffects at three months (after diagnosis)."

However, after one year, the gap had narrowed, with 32.1% of men and 34.5% of women still experiencing symptoms. Among men, coughing, joint pain, muscle pain, and numbness in the hands and feet were observed.

(Japanese original by Mikako Shimogiri, Lifestyle and Medical News Department)