Covid reader: 16 July
by Steve Brown
16 July 2021
The scientific advice behind July's relaxation of rules, why NHS pressure is not just about Covid admissions and the value of isolation. Our new weekly review highlights key further reading from the last week
The case for removing restrictions
Scientific Advisory Group for Emergencies, 7 July minutes
We are constantly being told that the country’s response to Covid-19 is being ‘led by the science’. But the messages we hear can depend on who is quoting the science at you – whether that is a politician, a media outlet or specific interest group. Far better to go to the horse’s mouth then and the Scientific Advisory Group for Emergencies (Sage) is probably as close as we can get. The minutes for its 7 July meeting were published this week providing some interesting thoughts on how the planned blanket removal of restrictions in England could impact on the NHS.
There are lots of uncertainties in Sage’s modelling of the potential effects of the move to step 4 of the government’s roadmap. How will behaviours change, the level of vaccine effectiveness, and vaccine uptake are some of the key ones. ‘It is important to note that even small changes in these assumptions (eg a 92% uptake rather than a 96% uptake, or small changes in how people behave after step 4 is taken) have significant effects on modelled outcomes,’ the advisory body said.
In all the scenarios, there is a period of extremely high prevalence of infection lasting until at least the end of August. How high is not clear. A high number of infections creates four risks:
- An increase in hospitalisations and deaths
- More long Covid
- Workforce absences (including in the NHS)
- Increased risk of new variants
High prevalence also presents a challenge to testing, contact tracing and sequencing. ‘If PCR testing and genomic sequencing capacity are overwhelmed, it may not be possible to rapidly identify a new variant,’ the minutes report.
The number of hospital admissions is highly uncertain but likely to reach at least 1,000 per day, depending on the speed of changes following step 4. Most modelled scenarios have peaks lower than January 2021. However, with more pessimistic assumptions, the resurgence exceeds the January numbers. One model from the University of Warwick suggests that with the most rapid return to pre-pandemic behaviours over the course of a month, daily admissions could be between 1,300 and 4,800.
Delaying step 4 by four weeks from 21 June has enabled more vaccinations to be administered and moved the end of restrictions closer to the school holidays, when transmission is expected to be lower. A further delay would have some additional benefit, but this would be smaller than the current delay and would push the wave further towards the autumn and winter. However the scientists are clear that the country needs to return to pre-pandemic behaviours gradually, over several months. ‘If the aim is to prevent the NHS being under pressure the priority should be to avoid a very rapid return to pre-pandemic behaviour which could lead to a peak in hospitalisations similar to (or possibly even higher than) previous peaks,’ they said.
Not just about hospitalisations
NHS Providers, Chris Hopson BMJ blog
In a blog first published in the BMJ, NHS Providers chief executive Chris Hopson acknowledges the fact that vaccines have weakened the link between infection and the high levels of hospitalisation and death seen in previous waves of Covid-19.
But even with a lower conversion rate from infections to hospitalisations, the NHS still faces significant pressure. ‘Just focusing on the potential level of Covid-19 admissions completely misses the broader picture,’ he writes. Instead you need to look at the total demand the NHS is currently coping with and the significant capacity constraints it is juggling.
There are five issues at play.
- Trusts are flat out trying to tackle the backlog of care built up over the last 18 months. Trusts are working at maximum capacity including extended use of theatres and weekend working. And there are backlogs outside the acute sector too.
- Urgent and emergency care pressures, partly driven by an increase in complexity and severity of some patients’ conditions.
- Trusts have reduced capacity due to infection control measures – with 12% fewer beds according to some reports. This is pushing up occupancy levels with more than a third of trusts operating at more than 95% occupancy.
- There are staff shortages – with pressure from exhausted staff taking deserved leave and because of staff self-isolation as a result of rising community infection rates.
- Covid admissions are rising. ‘If a river is full and the ground is sodden, it doesn’t take much extra rain for the banks to burst,’ said Mr Hopson.
In response, NHS Providers wants to see a review of self-isolation requirements if staff are double jabbed. It also wants the government to be ‘honest, open and clear’ on the pressures facing the NHS and the trade-offs that will have to be made. But mostly it calls for the spending review to provide a ‘proper match between NHS demand and capacity’ as well as an appropriate pay settlement.
The value of isolation
Statistician David Spiegelhalter, The Guardian comment
Statistics about Covid-19 can be bewildering, which is why it can be useful to keep a friendly stats professor handy. Enter David Spiegelhalter. Sir David is chair of the Winton Centre for Risk and Evidence Communication at the University of Cambridge and a former past president of the Royal Statistical Society (RSS). While a regular contributor to BBC Radio 4’s popular More or less statscast, he can currently be found hanging out manning a weekly column on The Guardian with RSS statistical ambassador Anthony Masters. Their latest translation of numbers for the masses provides some interesting figures around the value of self-isolating – balancing the reduction in cases against the economic cost.
Sir David highlights that 10% of the 7.5 million close contacts reached by NHS Test and Trace became lab-confirmed cases themselves. And those that do go on to test positive may have already passed on the virus before they were contacted – the median time to reach contacts after the initial case first reported symptoms is around four days. He also highlights a Public Health England technical report that shows an estimated 11% of household members and 6% of other contacts of Delta cases had confirmed infections.