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Different aftereffects reported between omicron and delta, earlier strains: Japan study

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SHIZUOKA -- The most common COVID-19 aftereffects reported by patients who had contracted the omicron variant were coughing and headaches, compared to the lasting effects on one's senses of smell and taste seen primarily among patients infected with the delta variant or earlier strains, according to a study by the Shizuoka Prefectural Government.

    The prefectural government in central Japan defines coronavirus aftereffects as symptoms that last for four weeks or longer after contracting the virus and cannot be explained as other diseases, and has been carrying out research on the subject since the end of 2021. This is the second interim report released by the prefectural government since February 2022.

    Of the 291 people who responded to the prefecture's survey on aftereffects, 188 who got infected with the coronavirus in December 2021 or earlier were considered as those contracting the delta or earlier variants, while 103 who tested positive for the virus in January 2022 or later were regarded as getting infected with omicron.

    The aftereffects that the omicron group thought were the worst included coughing, cited by 28% of the respondents, headaches (17%) and fatigue (15%), among other symptoms. Meanwhile, those infected with the delta or preceding variants listed the altered sense of smell (19%), effects on the sense of taste (13%) and hair loss (12%), highlighting stark differences depending on the timing of their infection.

    The potential causal relationship between COVID-19 aftereffects and the third booster vaccine shots have not been clear. Shizuoka Prefecture's health and welfare department director Mikio Goto said, "As far as the (survey) results show, we cannot determine that vaccines will prevent aftereffects. I'll wait to comment on the relationship (between the aftereffects and vaccines) until future studies become available."

    The prefectural government additionally asked the respondents about whether they had gone to see a doctor about the aftereffects. As a result, some 40% of those who had experienced aftereffects from the delta or earlier variants went to get checked, while the figure dropped to roughly 20% in the omicron group. Many of those who had prolonged coughing or headaches -- leading aftereffects for the omicron variant -- likely judged they could deal with such symptoms using commercially available medications.

    In the February interim report, some 60% of those who didn't go see a doctor after experiencing aftereffects said they didn't know where to go for diagnosis. The prefectural government has since released on its website a list of medical institutions that are available for examining coronavirus aftereffects.

    Many factors regarding the causes of COVID-19 aftereffects remain unclear. There is no established treatment, and the basic medical practice provides patients with treatment according to their symptoms.

    (Japanese original by Rinnosuke Fukano, Shizuoka Bureau)

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