Variation in the prevalence of cough symptoms 4-5 days after infection with SARS-CoV-2 between seasons with different prevalent strains.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a major global health concern in 2022. The association between the rapid spread of the variants, which eliminated the original strain, and clinical manifestations with the variants remains undetermined. This was a population-based longitudinal cohort study. Whole citizens in a city with approximately one million population who had contacted COVID-19 patients and were tested by nasopharyngeal SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) swab test between July 2020 and March 2021 were enrolled. Detailed contact episode and the presence of cough symptoms 4-5 days after contact with patients having COVID-19 were evaluated. Among the 359 RT-PCR test-positive patients, 88 (24.5%) developed cough symptoms by 4-5 days from the infection. The same rate in RT-PCR test-negative cases was 8.6%. The prevalence of cough did not significantly differ by age, sex, and places or closeness of the contact episode. The rate of cough symptoms in RT-PCR test-positive patients increased in February-March 2021 with E484K variant predominance compared to that in July-December 2020 with the original strain (32.9% vs 19.4%, p = 0.0221), whereas the cough prevalence among RT-PCR test-negative population did not increase. Cough symptoms in COVID-19 patients was associated with strong fatigability, but was independent from fever or dysosmia. Cough symptoms 4-5 days after infection with SARS-CoV-2 was suggested to have increased with E484K variant, compared to the original strain.