Viral respiratory diseases (including influenza and COVID-19) in Scotland surveillance report
As at 1 May 2023

About this release

This is a weekly release by Public Health Scotland (PHS) on epidemiological information on seasonal respiratory infection activity in Scotland including COVID-19.

Since the beginning of the COVID-19 pandemic, health care services have functioned differently now compared to previous winter respiratory seasons, so the consultation rates are not directly comparable to historical data.

Main points

Overall assessment for week 17 (week ending 30 April 2023):

• The proportion of NHS24 calls that were for respiratory symptoms in week 17 remained at Baseline activity level.
• Influenza remained at Baseline activity level (0.8 per 100,000 population). There were 43 laboratory-confirmed influenza cases: one type A(H3), six type A (not subtyped) and 36 type B. This compares to 70 laboratory-confirmed cases reported during week 16.
• Adenovirus remained at Low activity level. Parainfluenza decreased from Moderate to Low activity level.
• In the CARI sentinel surveillance programme, rhinovirus was the most commonly detected pathogen with a swab positivity of 14.8%. Influenza B decreased to 2.7% in week 17. SARS-CoV-2 positivity decreased to 5.9% in week 17 from a peak of 11.0% in week 11. Parainfluenza decreased and was at 11.3% in week 17.
• The overall number of emergency hospital admissions associated with RSV, influenza and SARS-CoV-2 has decreased from the high plateau seen in weeks 51 and 52. The largest proportion of admissions in week 16 (92%) was for SARS-CoV-2, while the individual number of admissions decreased for SARS-CoV-2, influenza, and RSV.
• During the period 8 April 2023 to 21 April 2022, wastewater COVID-19 levels decreased from the previous 2 week period (19 to 35 Mgc/p/d).
• There were on average 725 patients in hospital with COVID-19, a 22.6% decrease from the previous week ending 23 April 2023 (937).
• During the current spring vaccination programme, a total of 229,587 COVID-19 vaccines have been delivered to eligible adults currently resident in Scotland.

Background

Surveillance of respiratory disease pathogens is a key public health activity as infection is associated with appreciable levels of morbidity and mortality, especially during the winter months and particularly among those at risk of complications, including the elderly, children under two years of age, those with chronic health problems, and pregnant women. 

Respiratory infection can be caused by a number of pathogens and there is no single surveillance system or data source that can describe the onset, severity and impact of SARS-CoV-2, influenza and other respiratory pathogens, or the success of any control measures. In Scotland, respiratory infection levels and their impact are monitored using various sources of data, including microbiological sampling and laboratory test results from community and hospital settings, NHS 24 calls, primary care consultations, and hospital (including intensive care) admissions. The intelligence generated from these different data sources provide a comprehensive picture of current respiratory illness in Scotland. 

Seasonal patterns and variations 

Many respiratory illnesses, including influenza, are typically associated with a seasonal increase in the autumn and winter. These seasonal patterns have been established based on many years of surveillance data. However, in some cases, circulation of these pathogens have deviated from their usual seasonal trends due to changes in social mixing patterns during the COVID-19 pandemic.  

As yet, SARS-CoV-2 has not been shown to follow the same seasonal patterns as other respiratory pathogens. Increases in infections outside the winter season may be occurring for a variety of reasons, including the emergence of new variants and time-varying fluctuations in population immunity associated with SARS-CoV-2 infection.​

Further information

The next release of this publication will be 11 May 2023.

Find out more

Previous Publications

Versions of the Weekly national respiratory report publication released before 30 November 2022 may be found on the Public Health Scotland website.

Versions of the COVID-19 weekly statistical report publication released before 30 November 2022 may be found on the Public Health Scotland website.

Open data

Open data from this publication is available from the following weblinks:

• Viral respiratory diseases Open Data platform
• Flu and COVID vaccination uptake Open Data platform

Further data

• The COVID-19 Vaccine Wastage datafile was updated on 18 April 2024 to include the most recent information.
• The COVID-19 in Adult Care Homes in Scotland datafile was updated on 27 July 2023 to include more recent information.
• 28 September 2022 COVID-19 statistical report publication contains information on COVID-19 infection and vaccination in pregnancy in Scotland.
• 2 March 2022 COVID-19 statistical report publication contains information on Highest Risk (shielding patients list)
• 7 November 2023 Community Acute Respiratory Infection (CARI) surveillance in primary care contains information on flu Vaccine effectiveness in community settings.
• 25 May 2023 Interim 2022/23 influenza vaccine effectiveness: six European studies, October 2022 to January 2023, contains information on flu Vaccine effectiveness in hospital settings.
• 13 January 2024 Estimated number of lives directly saved by COVID-19 vaccination programs in the WHO European Region, December 2020 to March 2023, contains information on lives saved due to COVID-19 vaccination