Weekly national seasonal respiratory report
Week 45 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 level. There were 10 influenza cases: one type A(H3), two type A (subtype unknown) and seven type B. This compares with 11 influenza cases reported in week 44.
• Respiratory syncytial virus (RSV) increased from Baseline to Low 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 2021, week on week increases in laboratory-confirmed diagnoses for RSV were reported between week 23 and week 40. Cases have declined over consecutive weeks since the peak in week 40 but a slight increase has been noted for week 45.
• Coronavirus (non-SARS-CoV-2) and rhinovirus were at Moderate activity level.
• Human metapneumovirus (HMPV) and parainfluenza were at Low activity level. 
• The proportion of NHS24 calls for respiratory symptoms in week 45 remained at Moderate activity level overall. The over 75 age group remained at Baseline activity level and the 65-74 age group remained at Low activity level. The 45-64 age group increased from Low to Moderate activity level. The 15-44 age group and 1-4 age group remained at Moderate activity level. The 5-14 and the under 1 age groups decreased from Moderate to Low activity level.
• Influenza vaccine data are presented and indicate that at least 1,697,724 eligible individuals are estimated to have received their vaccine.

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 25 November 2021.