Objective  To understand the epidemiological characteristics of infections with human parainfluenza viruses (HPIVs) in patients with acute respiratory tract symptoms in Beijing from 2020 to 2023.

  Methods  Clinical samples of patients with acute respiratory infection were collected in 35 sentinel hospitals in Beijing and tested for HPIV-1, HPIV-2, HPIV-3, HPIV-4 and other common respiratory tract viruses.

  Results  The overall HPIV positive rate in Beijing from January 2020 to February 2023 was 3.22% (486/15106), with the lowest HPIV positive rate in 2020 (1.65%, 70/4234), followed by an increase to 5.61% (214/3817) in 2022 and 2.54% (27/1062) during January-February 2023. The annual infection peak of HPIV was in autumn. In addition, the HPIV positive rate in October 2022 (23.05%, 74/321) was higher than that in any month between 2020 and 2023. In 2020−2023 HPIV-3 was the most commonly detected (2.11%, 318/15106), followed by HPIV-1 (0.73%, 111/15106), HPIV-2 (0.24%, 36/15106) and HPIV-4 (0.15%, 22/15106). But after 2022, the positive rate of HPIV-1 decreased obviously, while the positive rate of HPIV-2 increased significantly. HPIVs were mainly detected in people aged 0-5 years (8.50%, 176/2070), 6−17 years (4.10%, 49/1195) and over 60 years (2.82%, 147/5214). Children aged 0−5 years were susceptible to severe pneumonia caused by HPIV-3 with a positive rate of 8.51% (12/141).

  Conclusion  In 2020−2023, the incidence intensity of HPIV infection was significantly suppressed in the initial phase and gradually rebounded in the later phase; the peak of HPIV infection was delayed, which might influence the incidence of HPIV infection in future.