How will Covid affect the NHS this winter?

On the one hand, given that this is our third winter with the virus and our second in which a majority of the population has been vaccinated - many several times - our immune defences against severe disease and death are substantially higher than they were back in 2020.

This is illustrated by the fact that by April of this year, according to data from NHS Grampian, the proportion of Covid positive patients being admitted to hospital because of the infection had fallen to just 20 per cent (compared to 57% as recently as the beginning of January this year).

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None of this was to suggest that Covid was not piling enormous pressure on the health service, however.

What became clear during successive waves of Omicron and its BA.2 and BA.5 sublineages was that very high rates of Covid in the community (peaking with an estimated one in 11 Scots infected in March; pre-2022, it had never been higher than than one in 45) translated into serious disruption for the NHS.

Covid rates have been higher during 2022 than in the previous two years of the pandemic (Source: PHS from Office for National Statistics household infection survey) (Image: PHS)

Staff absences rocketed; outbreaks in care homes had a knock on effect for delayed discharge in hospital, because premises would be forced to close temporarily to new admissions; and requirements to separate Covid and non-Covid patients, regardless of symptoms, reduced bed availability on wards.

Undoubtedly this has been a contributory factor (though certainly not the sole cause) of the tragic logjams we have seen in A&E departments this year, as thousands of patients have languished on trolleys for more than 12 hours - sometimes days - while doctors tear their hair out trying to find an empty bed for them in the hospital.

READ MORE: NHS crisis has been years in the making - Covid just accelerated it

There are signs that Covid is on the march once again, so how will the NHS cope with it this winter?

Well, the short answer is by not testing for it in the first place.

As of September 28, updated guidance from the Scottish Government has removed the requirement for frontline healthcare workers and social care staff to regularly test themselves for Covid. They will only be expected to do so now if they have symptoms.

The requirement to test all patients for the virus on admission, and during their stay, has also been dropped.

It now applies only in the case of immuno-compromised patients prior to elective surgery, patients with symptoms, and as part of outbreak management.

Only people about to move into a care home are still being routinely tested for the virus.

The number of people in hospital with Covid rose 25 per cent, from 611 on September 17 to 762 by October 1. However, reductions in hospital patient testing mean this will no longer be an accurate gauge for the prevalence of the virus in the community (Source: PHS) (Image: PHS)

The rules in Scotland mirror those already adopted in England, but both governments say they will be "kept under review".

What impact might it have?

The optimistic take is that axing asymptomatic Covid testing will significantly reduce staff absences, increase the number of available beds, and thus help to alleviate throughput from A&E to wards.

It is difficult to quantify exactly what proportion of Covid cases are asymptomatic but several studies put the figure around 50%, maybe as much as 80% in young people, but it depends what you define as "Covid symptoms" (a sore throat seems to be more common now that loss of taste or smell).

According to Public Health Scotland, around 62% of patients who catch the virus while in hospital are asymptomatic at the time they test positive.

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For detractors, however, it is a defeatist approach which will increase hospital transmission of the virus (already around 30% of people "in hospital with Covid" are patients infected post-admission) when the priority should be making indoor air safer, for example through better ventilation and high-grade masks.

Catching Covid in hospital can also slow some patients' recovery time, meaning beds end up occupied longer. 

Ultimately it comes down to a balance of risks and, for now, policymakers favour increased capacity.

Waiting list backlogs and A&E bottlenecks are themselves contributing to hundreds of avoidable deaths.

On the other hand Covid was still directly responsible for around 40% of Scotland's excess deaths in the past six months, despite its lethality (thanks to vaccines, antivirals, repeat exposure and Omicron) now being on a par with flu.

Flu rates in Scotland (red line, week 39 = up to October 2) are low but higher than average for the time of year and rising (Source: PHS) (Image: PHS)

Influenza, however, is another reason why maximising capacity is the priority.

Currently flu rates in Scotland are low but higher than average for the time of year - and creeping up.

If we do see a resurgence, as Australia did, it is likely to be sudden, steep and earlier than normal.

Of course, one thing which might force a U-turn is a new and worrisome Covid variant.

There is no sign of an entirely new strain, but Omicron's sublineages seem to be evolving and re-combining into ever more immunity-dodging forms.

This would only really upend current winter plans if it led to many more people being symptomatic (and thus tested), or if it considerably eroded vaccine protection against severe illness as well as infection - resulting in many more people being hospitalised because of Covid.

An 'Omicron family tree' showing how substrains have evolved from the Omicron BA.1 parent (Source: @dfocosi Twitter) (Image: kk)

The outlook on this front is unclear.

A couple of offshoots in particular - B.Q.1.1 (a descendent of BA.5, which drove Scotland's most recent wave) and BA.2.75.2 (a descendent of the so-called Centaurus strain of Omicron which was behind a surge of infections in India) - have caught scientists' attention.

Early research suggests that previous BA.5 infections and antibody drugs, including Evusheld, would have very weak ability to stop infections caused by either B.Q.1.1 or BA.2.75.2.

READ MORE: Cases of B.2.75 'Centaurus' detected in Scotland 

Another, XBB, was described by immunologist Yunlong Richard Cao as "the most antibody-evasive strain tested" with the potential to cause "significant immune escape at a scale never seen before".

The Beijing-based scientist tweeted that XBB's immune-escaping capability is "comparable to or even exceeding SARS-CoV-1" - the coronavirus behind the 2003 SARS outbreak.

With mitigations against the virus spreading all but gone, all we can really do is watch, wait, and hope for the best.