Viral respiratory diseases (including influenza and COVID-19) in Scotland surveillance report
As at 24 April 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 16 (week ending 23/04/2023):

• Influenza remained at Baseline activity level (1.3 per 100,000 population). There were 69 laboratory-confirmed influenza cases: one type A(H3), two type A(H1N1)pdm09, 17 type A (not subtyped) and 49 type B. This compares to 43 laboratory-confirmed cases reported during week 15
• HMPV remained at Low activity level. Parainfluenza remained at Moderate activity level
• In the CARI sentinel surveillance programme, rhinovirus was the most commonly detected pathogen with a swab positivity of 16.0%. Influenza B increased to 4.6% in week 16. SARS-CoV-2 positivity decreased to 5.8% in week 16 from a peak of 10.9% in week 11. Parainfluenza increased and was at its highest at 15.5% in week 16
• 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 15 (91%) was for SARS-CoV-2, with the individual number of admissions for SARS-CoV-2, influenza and RSV decreased
• During the period 2 April 2023 to 15 April 2023 wastewater COVID-19 levels were in the range of 24 to 40 million gene copies per person per day (Mgc/p/d)
• There were on average 937 patients in hospital with COVID-19, a 16.5% decrease from the previous week ending 16 April 2023 (1,122)
• During the current spring vaccination programme, a total of 159,001 COVID-19 vaccines have been delivered to 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 4 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 14 September 2023 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
• The COVID-19 Vaccine Wastage datafile was updated on 18 April 2024 to include the most recent information.