Trends in human parainfluenza virus in Scotland before and after the peak of the COVID-19 pandemic, January 2017 to October 2023

Abstract

BackgroundHuman parainfluenza viruses (HPIV) commonly cause upper respiratory tract infections, with potential for severe lower respiratory complications. Understanding seasonal increases informs strategies to prevent HPIV spreading.AimWe examined the impact of COVID-19 on HPIV epidemiological and clinical patterns in Scotland using non-sentinel and sentinel surveillance data.MethodsInformation on HPIV swab positivity (January 2017-October 2023) and demographic data was obtained from the Electronic Communication of Surveillance in Scotland (ECOSS) non-sentinel surveillance sources (laboratory-based data from hospital and community) and the Community Acute Respiratory Infection (CARI) sentinel surveillance programme (enhanced surveillance and symptom data).ResultsIn 2020 during early COVID-19 waves, HPIV detection decreased aligning with lockdowns and preventive measures. In summer 2021, HPIV positivity increased, with HPIV-3 possibly reverting to pre-pandemic seasonality, but HPIV-1 not yet re-establishing alternate-year peaks. Most positive results from non-sentinel sources came from hospital tests. Sentinel surveillance (CARI) complemented non-sentinel data, offering community-level insights. There was no significant difference in CARI swab positivity by sex in any age group. Consistent with historical trends, children under five years exhibited highest test positivity: 9.3% (95% CI: 7.6-11.2) in females and 8.5% (95% CI 7.0-10.2) in males.ConclusionThe COVID-19 pandemic impacted HPIV detection in Scotland. The decline during the pandemic peak and subsequent partial resurgence underscores the complex interplay between viral epidemiology and public health measures. Combining diverse surveillance systems provides a comprehensive understanding of HPIV dynamics. Insights into age-specific and symptom-associated patterns contribute to understanding HPIV epidemiology and refining public health strategies.

Keywords: COVID-19 pandemic; Human parainfluenza viruses; epidemiology; respiratory infections; surveillance.

Figure 1

Rates of positive human parainfluenza virus samples from tests undertaken in the community and in hospitals (non-sentinel sources, Electronic Communication of Surveillance in Scotland) stratified by (A) surveillance source and (B) human parainfluenza virus type, Scotland, January 2017–October 2023

Figure 2

Overall human parainfluenza virus swab positivity in the Community Acute Respiratory Infection (CARI) sentinel surveillance programme (A) over time and (B) stratified by human parainfluenza virus type, Scotland, November 2021–October 2023 (2021/22 and 2022/23)

Figure 3

Human parainfluenza virus swab positivity in the Community Acute Respiratory Infection (CARI) surveillance programme and number of positive human parainfluenza virus samples by type, stratified by age and sex, Scotland, November 2021–October 2023 (2021/22 and 2022/23)

Figure 4

Human parainfluenza virus swab positivity in the Community Acute Respiratory Infection (CARI) surveillance programme and number of positive human parainfluenza virus samples, stratified by HPIV type, age and sex, Scotland, November 2021–October 2023 (2021/22 and 2022/23)