Information

Coronavirus (COVID-19): state of the epidemic - 29 April 2022

This report brings together the different sources of evidence and data about the Covid epidemic to summarise the current situation, why we are at that place, and what is likely to happen next.

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Estimated Infection Levels and Case Numbers

Estimated Infection Levels

The UK Health Security Agency's (UKHSA) consensus estimate for R in Scotland as at 12 April is between 0.8 and 1.0. The lower and upper limits of the R value have both remained unchanged since the previous publication (Figure 1)[3] [4].

Figure 1: R in Scotland over time by publishing week [5].

a graph showing the estimated range of R over time from April 2021 to April 2022. The estimated lower and upper range moved above 1 in June 2021, September 2021 and January 2022. As at 12 April the estimate for R in Scotland is between 0.8 and 1.0. The chart has a note on 1 April 2022 that says: “change to fortnightly publication schedule”.

As at 12 April, the UKHSA's consensus view was that the incidence of new daily infections in Scotland was between 191 and 569 per 100,000 people. This equates to between 10,400 and 31,100 people becoming infected each day in Scotland[6] [7].

The latest growth rate for Scotland as at 12 April was between -5% and -1%. The upper growth and lower growth limit have both decreased since the last published figure[8] [9].

Covid Infection Survey

In Scotland, the percentage of people testing positive for Covid-19 as estimated by the Covid-19 Infection Survey continued to decrease in the most recent week (17 to 23 April), as seen in Figure 2[10]. The estimated percentage of people testing positive in Scotland has been decreasing since late-March. This follows a peak in the week 14 to 20 March 2022 which saw the highest estimate for Scotland since the survey began. The estimated percentage of people testing positive for Covid-19 in the private residential population in the week 17 to 23 April in Scotland is 4.14% (95% credible interval: 3.68% to 4.63%)[11], equating to around 1 in 25 people (95% credible interval: 1 in 25 to 1 in 20).

In the week 17 to 23 April 2022, estimates for the other nations of the UK are as follows and can be seen in Figure 2:

  • In England, the percentage of people testing positive continued to decrease: 4.42% (95% credible interval: 4.27% to 4.58%), equating to around 1 in 25 people (95% credible interval: 1 in 25 to 1 in 20).
  • In Wales, the percentage of people testing positive continued to decrease: 5.67% (95% credible interval: 4.98% to 6.41%), equating to around 1 in 18 people (95% credible interval: 1 in 20 to 1 in 16).
  • In Northern Ireland, the percentage of people testing positive decreased over the most recent two weeks, but the trend was uncertain in the most recent week: 4.07% (95% credible interval: 3.30% to 5.00%), equating to around 1 in 25 people (95% credible interval: 1 in 30 to 1 in 20).
Figure 2: Modelled daily estimates of the percentage of the private residential population testing positive for Covid-19 in the four UK nations, between 13 March and 23 April 2022, including 95% credible intervals [12].

a line chart showing the modelled daily estimates of the percentage of the private residential population testing positive for Covid-19 in each of the four nations of the UK, between 13 March and 23 April 2022, including 95% credible intervals. In the most recent week, the estimated percentage of people testing positive continued to decrease in Scotland, England and Wales. The estimated percentage of people testing positive in Northern Ireland decreased in the most recent two weeks, however the trend was uncertain in the most recent week.

In Scotland, the estimated percentage of people testing positive has decreased among older adults. However, the trend was uncertain in young adults and children of nursery/primary and secondary school ages[13].

Wastewater Estimates

Nationwide, wastewater Covid-19 levels have overall reduced in the last two weeks. The week ending 26 April saw levels of around 130 million gene copies per person per day (Mgc/p/d), a slight rise compared to 116 Mgc/p/d the previous week (week ending 19 April), but lower than 220 Mgc/p/d the week before (week ending 12 April) (Figure 3)[14].

Although overall there are decreases in wastewater Covid-19 levels across most of Scotland in the last two weeks, 18 local authorities have increased their levels over the past week. Increases were reported in Aberdeen City, Aberdeenshire, Angus, Argyll and Bute, Clackmannanshire, Dumfries and Galloway, Dundee City, East Ayrshire, East Dunbartonshire, Fife, Glasgow City, Highland, Inverclyde, North Ayrshire, Perth and Kinross, South Ayrshire, South Lanarkshire and West Lothian. Please note that comparisons for Na h-Eileanan Siar, Shetland and Stirling are not possible due to sampling coverage.

Figure 3: National running average trends in wastewater Covid-19 from 31 December 2021 to 26 April 2022, and CIS positivity estimates from 31 December to 17 April 2022 [15] [16] [17].

a line chart showing the national running average trends in wastewater Covid-19 from the end of December 2021 to the end of April 2022, and CIS positivity estimates from the end of December 2021 to mid-April 2022. After a steep decrease in early January, Covid-19 wastewater levels appear to fluctuate throughout January and February, with a peak in late March and decreasing levels from early April.

Covid-19 Cases

By specimen date, the seven-day combined PCR and LFD case rate (including reinfections) continued to decrease in Scotland in the week leading up to 24 April. This follows a period of sharply increasing case rates from late February to mid-March. There were 400 weekly combined PCR and LFD cases per 100,000 population in the week to 24 April, which is a 28% decrease from 557 weekly cases per 100,000 on 17 April (Figure 4)[18].

Figure 4: Seven-day combined PCR and LFD case rate (including reinfections) per 100,000 for Scotland by specimen date. Data to 24 April 2022 [19] [20].

a line graph showing the seven-day case rate (including reinfections) by specimen date per 100,000 people in Scotland, using data from March 2020 up to and including April 2022. In this period, weekly case rates have peaked in January 2021, July 2021, September 2021, early January 2022, and mid-March 2022. The chart has notes explaining that before 5 January 2022, the case rate includes only positive laboratory confirmed PCR tests. After 5 January 2022, the case rate includes PCR and LFD confirmed cases. From 18 April 2022, the Universal LFD Offer for asymptomatic testing is no longer available, so caution should be advised when comparing trends in cases over time.

The week leading up to 24 April saw decreasing case rates in all age groups compared to the week ending 17 April. In the most recent week, the decrease ranged from 20% for those aged 19 or younger, to 34% for those aged 60 to 69 (Figure 5)[21]. Meanwhile CIS estimates indicate the estimated percentage of people testing positive has decreased among older adults. However, the trend was uncertain in young adults and children of nursery/primary and secondary school ages[22].

Figure 5: Weekly total combined PCR and LFD cases (including reinfections) per 100,000 population in Scotland by age group, by specimen date. Data to 24 April 2022 [23] [24].

a line graph showing the weekly total combined PCR and LFD case rate (including reinfections) by specimen date per 100,000 people by age group, from December 2021 to April 2022. All age groups saw a peak in weekly case rates in early January and in mid-March 2022. The chart has notes explaining that before 5 January 2022, the case rate includes only positive laboratory confirmed PCR tests. After 5 January 2022, the case rate includes PCR and LFD confirmed cases. From 18 April 2022, the Universal LFD Offer for asymptomatic testing is no longer available, so caution should be advised when comparing trends in cases over time.

Rising numbers of weekly Covid-19 cases among care home residents throughout February and March were in line with the increasing case numbers among older age groups in the same period. The number of Covid-19 cases among care home residents peaked in the week to 11 March, with 938 reported cases. Case numbers have since decreased, and in the week to 22 April there were 170 reported cases among care home residents, which is a decrease of 41% from the previous week ending 15 April (287 cases)[25].

According to data from ARHAI Scotland, 98.1% of the 50,451 Covid-19 Cases reported in the week ending 3 April 2022 were reported as community onset cases. 389 cases in the same period were reported as nosocomial cases[26]. This is an 18% decrease from the previous week ending 27 March (473 nosocomial cases). This follows a period of increasing numbers of nosocomial cases since the beginning of February (following a peak in late December 2021 and early January 2022). The number of cases in all categories of inpatient diagnosed COVID-19 cases increased during the same time period, including those diagnosed on day one or two, reflecting the high levels of transmission in the community[27].

Reinfections

The increase in the proportion of reinfections seen in late 2021 corresponds to the emergence of the Omicron BA.1 variant in the UK. The proportion of reinfections in Scotland when Omicron BA.1 was first detected on 29 November[28] was 0.8% percent of total cases. These are cases in individuals for whom it has been 90 or more days since their last positive Covid-19 test.

The proportion of reinfections among the total weekly cases has increased in the most recent week. By specimen date, there was an total number of 2,726 reinfection cases confirmed by either a PCR or LFD test in the week leading up to 24 April. These represent 12.5% of reported cases, which is an increase from 10.7% in the week leading up to 17 April. This is the highest level of reinfections seen in the pandemic (Figure 6)[29].

Figure 6: Number of PCR and LFD positive cases by episode of infection and specimen date. Data to 24 April 2022 [30] [31].

a bar chart showing daily PCR and LFD case numbers by episode of infection (first infection or reinfection) by specimen date from March 2020 to April 2022 with a line showing the seven-day average proportion of daily cases that are reinfections. The number of daily reinfection cases is not visible until late 2021. The seven-day average proportion of reinfections peaked in July 2020, April 2021 and early January 2022, and increased to its highest levels so far since then. The chart has notes explaining that before 5 January 2022, the case rate includes only positive laboratory confirmed PCR tests. After 5 January 2022, the case rate includes PCR and LFD confirmed cases. From 18 April 2022, the Universal LFD Offer for asymptomatic testing is no longer available, so caution should be advised when comparing trends in cases over time.

LFD Testing

The weekly total number of LFD tests reported in the week to 24 April decreased by 22% from the previous week leading up to 17 April. There were 223,503 reported tests in the week to 24 April (Figure 7)[32]. Please note that from 18 April LFD Universal Offer for asymptomatic testing is no longer available.

Figure 7: Number of LFD Tests Reported. Data up to the 24 April 2022 [33] [34].

a line chart showing a trend in the number of LFD tests reported in Scotland from December 2020 until April 2022. It shows a fluctuating but increasing trend until December 2021, with peaks in March 2021, September 2021, November 2021,  December 2021 and March 2022. The number of reported LFD tests has been on a decreasing trend since then. The chart has notes explaining that before 5 January 2022, LFD tests were not used to officially confirm a Covid-19 case. After 5 January 2022, Covid-19 cases could be confirmed using PCR and/or LFD tests. From 18 April 2022, the Universal LFD Offer for asymptomatic testing is no longer available, so caution should be advised when comparing trends in testing over time.

The Scottish Contact Survey[35] asks whether people use LFD tests and if so how often. Approximately 68% of individuals had taken at least one lateral flow test within the last 7 days for the survey pertaining to the period 14 April to 20 April, decreasing from 77% two weeks prior[36].

Contact

Email: sgcentralanalysisdivision@gov.scot

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