Coronavirus (COVID-19): modelling the epidemic (issue no. 49)

Latest findings in modelling the COVID-19 epidemic in Scotland, both in terms of the spread of the disease through the population (epidemiological modelling) and of the demands it will place on the system, for example in terms of health care requirement.


Key Points

  • The reproduction rate R in Scotland is currently estimated as being between 0.8 and 1.0. The range limits are higher than last week.
  • The number of new daily infections for Scotland is estimated as being between 1 and 15, per 100,000 people. The range limits are lower than last week.
  • The growth rate for Scotland is currently estimated as being between -4% and -1%. This is the same as last week.
  • Average contacts are still higher than seen during the lockdown period (when it averaged around 3 daily contacts) with a current level of 3.3 daily contacts.
  • Contacts within the work and school setting have shown a decrease in the last two weeks by 32% and 88% respectively.
  • Mean contacts within the 'other' setting (contacts outside of the school, home or work settings) have increased by approximately 11%.
  • Individuals aged 60 and over have increased their contacts in the last two weeks, while average contacts for those aged under 60 have remained level or have shown a decrease.
  • The 18-39 age group has shown a decrease in interactions with individuals under 18 whereas those aged 40-49 have increased their interactions with this age group.
  • The biggest change in the proportion of participants visiting different locations is seen in those visiting a hairdressers/beauticians[1], increasing from less than 1% to 20% in the last two weeks, followed by visits to non-essential shops[2], increasing from 14% to 22%.
  • Hospital bed and ICU occupancy are projected to fall over the next few weeks, but these both may plateau or increase as a result of all schools reopening and other relaxations of non-pharmaceutical interventions.
  • A major study reported in the Lancet[3] investigated the association between mass roll-out of the first doses of vaccines and hospital admissions in Scotland for COVID-19. Four weeks after receiving a first dose, the Pfizer-BioNTech vaccine was shown to reduce the risk of COVID-19 hospitalisation by 91% (95% CI 85 – 94), and the Oxford-AstraZeneca vaccine by 88% (95% CI 75 – 94). These results show an association with substantial reductions in the risk of COVID-19 hospitalisations across Scotland.
  • There were 4 local authority areas which exceeded what would be expected at this stage in the epidemic between 20-26 April. Dumfries and Galloway, Moray, Inverclyde and Glasgow City were areas of higher risk of transmission.
  • Modelled rates per 100K indicate that for the week commencing 9 May 2021 no local authorities have at least a 75% probability of exceeding 50 cases. This is the same as last week.

Contact

Email: modellingcoronavirus@gov.scot

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