As Covid-19 infection rates have soared in the UK, so too have alerts sent by the NHS COVID-19 app, the digital contact-tracing platform used in England and Wales. In the week to July 14, the most recent period for which data is available, 618,903 people were ‘pinged’ by the app, up from 530,126 alerts sent the week before.
The app works by detecting the time and distance between mobile devices via Bluetooth, counting 15 minutes spent within two metres as close contact between users. If anyone tests positive for Covid-19, they can anonymously share their test result with people they have come into close contact with. These people then receive a notification from their app telling them they must self-isolate for up to ten days.
Such vast numbers of alerts have led to commentators terming the phenomenon a ‘pingdemic’. Many businesses have struggled to stay afloat as staff members have self-isolated, prompting the government to release a list of sectors where staff are eligible for exemption from this requirement.
UK supermarket chain Iceland managing director Richard Walker said the company was having to close stores “due to staff absences – not because of Covid-19, but because of a broken and disruptive Track and Trace app”, while the London Underground network has seen closures due to key staff self-isolating.
From 16 August, fully vaccinated people and those under 18 in England will not need to self-isolate at all if they encounter someone who later tests positive, although they will still be advised to take a PCR test and must isolate if they then test positive themselves. So far, over 46 million people in the UK – nearly 90% of the adult population and about 70% of the overall population – have had their first vaccine dose, and more than 37 million – about 70% of adults and 56% of all people – have had both, figures that are only set to increase as time goes on.
As more and more people in England are inoculated against Covid-19, it’s hard to say what the future is for the NHS COVID-19 app, or whether Bluetooth-based contact-tracing still has a place in a vaccinated society without Covid-19 restrictions.
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While it is a legal requirement to isolate in the UK if contacted by NHS Test and Trace, it is not a legal requirement to do so when told to by the NHS COVID-19 app.
Does Bluetooth contact-tracing have a future?
Zühlke Engineering CEO Wolfgang Emmerich, whose team helped develop NHS COVID-19, tells Medical Device Network: “What we do know is that people who have been vaccinated can still get infected. Our Secretary of State for Health is a good example. We also don’t really know how long the vaccines will hold for and there are always going to be people who opt out of vaccination.
“The measures that are being taken when exposure is detected for somebody who has full vaccine coverage are going to be different from the ones that need to happen for people who have opted not to be vaccinated.”
Many commentators have suggested that the pingdemic problem could be solved by adjusting the parameters used by NHS COVID-19. Despite reports earlier this month suggesting that the app would be made less sensitive, with Transport Secretary Grant Shapps telling Sky News that it would be “tailored” to fall in line with new social distancing rules on 9 July, there are no current plans to alter the two metres for 15 minutes metric.
“The unfortunate fact of the matter is that many of [the individuals told to isolate by NHS COVID-19] are no more at risk of having contracted Covid than the rest of the population,” says ConsultMyApp founder Mike Rhodes. “The distancing used by the Test and Trace app is so extreme that even members of different flats who have never come into contact – and have a wall dividing them – could be ‘pinged’ if their fellow residents test positive.
“These sort of error margins were understandable, and potentially even tolerable, when Covid cases were averaging around 5,000 a day, but with that figure rising by over 900%, it is likely to cause severe disruption to society.”
Emmerich says that NHS COVID-19 has been constantly updated since launch, with about 170 releases so far. While there aren’t any current plans to change its sensitivity, the platform will be updated to reflect the 16 August changes to self-isolation requirements.
It may also be updated to include a wider range of symptoms that could signal Covid-19. The UK ZOE COVID Symptom Study has also found that sneezing, runny nose, headaches, sore throats and fevers seem to be more common now with the prevalence of the Delta variant than when other strains of the virus were dominant, while coughs and loss of smell appear to be less common.
Infections may have decreased due to the pingdemic
Despite the disruption caused to businesses, the pingdemic does still seem to have had an inhibiting effect on Covid-19 cases in the UK.
After a drastic spike in infection rates, cases in the country have fallen for the seventh day in a row as of 27 July – something Emmerich believes the pingdemic could be partially responsible for.
“Even in a population with a large proportion of vaccinations, infections can run wild,” he says. “The spike that occurred recently was in a broadly vaccinated population. We don’t really know why infections are currently falling. There are probably various reasons, of which the self-isolation of exposed contacts is probably one, but I’m pretty confident that the number of pings that we send out has also helped to dampen the rise of infections.”
However, a recent YouGov survey has suggested that one in ten previous users of NHS COVID-19 had deleted it while one in five still had the app installed but had disabled its contact-tracing capabilities, suggesting that the pingdemic may be causing the public to lose faith in the Bluetooth-based technology.
Emmerich says: “I can’t confirm the exact data in the YouGov survey but the overall trend is correct, there are some people starting to switch it off.”
Changing rules around self-isolation
As the pandemic moves towards endemicity in the UK, scientists are divided on what the rules surrounding Covid-19 and self-isolation should be.
Kings College London visiting professor in pharmaceutical medicine Dr Penny Ward told Science Media Centre: “In the early epidemic, when there was limited access to testing, and vaccines were not available, it was reasonable to advise individuals in contact with a case to self-isolate until a time at which they would be unlikely to be a risk to others. However in the ‘new’ post vaccinated world, not only are these individuals less likely to become infected in any case, but also would be less likely to transmit even if infected. This then suggests that it would be very reasonable to permit fully vaccinated individuals to continue to work as long as they can undergo PCR testing [and] test negative.”
However, not everyone shares this optimism.
University of Leeds associate professor of medicine Dr Stephen Griffin also told Science Media Centre: “The idea of exempting double-vaccinated individuals is […] a mistake in my opinion, regardless of what sector they might work in. We know vaccines are somewhat less effective at preventing infection compared to their protection from severe disease. Delta makes this all the more challenging as it can partly evade some antibody responses. This means that individuals can potentially be infected and infectious, whilst potentially being unaware that they are a carrier.”
Regardless of whether or how self-isolation laws should be changed, the fact remains that people in the UK are mixing far more than they were when Covid-19 cases have been at similar levels in the past. The respectively low levels of cases, hospitalisations and deaths relative to social contact demonstrates the powerful impact vaccines are having in the UK. It’s also become clear that if all restrictions on movement and social contact are going to be lifted then requiring all people who have been in contact with a positive case to isolate is no longer economically viable.