Weekly national seasonal respiratory report
Week 38 2021

About this release

This release is a weekly report on epidemiological information on seasonal influenza activity in Scotland. Due to the COVID-19 pandemic, health care services are functioning differently now compared to previous flu seasons so the consultation rates are not directly comparable to historical data.

Main points

Overall assessment:

• Influenza activity was at Baseline. There were two influenza cases detected in week 38: two cases of influenza B. This compares with 11 influenza cases reported in week 37.
• The proportion of NHS24 calls that were for respiratory symptoms in week 38 remained at Moderate activity level overall. The <1-year and 1-4 age groups were at High activity level. The 15-44 age group was at Moderate activity level. The 45-64 and 65-74 age groups were at Low activity level. The 5-14 and over 74 age groups were at Baseline activity level.
• Rhinovirus and respiratory syncytial virus (RSV) were at Moderate activity level. The large majority of RSV detections thus far have been in those aged under 5 years. The typical RSV season usually peaks between week 49 and week 52. However, in 2020/21, week on week increases in laboratory-confirmed diagnoses for RSV have been reported since week 23 2021 up until week 37. Week 38 is the first decrease observed since cases began to increase.  
• Coronavirus (non-SARS-CoV-2), human metapneumovirus (HMPV) and parainfluenza were at Low activity level for the first time in recent weeks.

Background

Surveillance of influenza infection is a key public health activity as it is associated with significant morbidity and mortality during the winter months, particularly in those at risk of complications of flu e.g. the elderly, those with chronic health problems and pregnant women.

The spectrum of influenza illness varies from asymptomatic illness to mild/moderate symptoms to severe complications including death. In light of the spectrum of influenza illness there is a need to have individual surveillance components which provide information on each aspect of the illness.

There is no single flu surveillance component that can describe the onset, severity and impact of influenza or the success of its control measures each season across a community.

To do so requires a number of complementary surveillance components which are either specific to influenza or its control, or which are derived from data streams providing information of utility for other PHS specialities (corporate surveillance data). Together, the influenza surveillance components provide a comprehensive and coherent picture on a timely basis throughout the flu season. Please see the influenza page on the HPS website (external website) for more details.

Further information

The next release of this publication will be 7 October 2021.