health

Busting Covid myths: Why those Covid temperature tests aren't just pointless – they're dangerous


The anticipation is palpable. In just over a fortnight, Britain will begin to spring back to life. Pub gardens will bustle and the pavements outside restaurants will be transformed for continental-style alfresco dining.

Gyms will throw open their doors, hairdressers will be ready to get to work on the nation’s lockdown locks. And, as Chancellor Rishi Sunak indicated on Thursday, working from home will start to end. No doubt, employers will be bending over backward to stay ‘Covid-safe’. This will mean employing measures from enforced mask-wearing and social distancing, to regular testing and enhanced cleaning regimes – much of which is now a legal requirement.

Debate continues to rage about the introduction of Covid immunity passports –proving an individual has had their jab.

But one practice, which does seem to have quietly become a mainstay of pandemic life, is proving just as controversial – in scientific circles at least.

Last year, scores of businesses, from fitness facilities and salons to pubs, restaurants and offices, required anyone who entered to have their temperature taken.

A fever is one of the three officially recognised signs of Covid-19, along with a cough and a loss of taste and smell.

The theory is that if you weed out those running even a mild temperature, you pick up hidden Covid cases. Those with a temperature above a normal 37 degrees must then isolate and take a test, removing them from the environment and curbing the spread of infection.

Experts say that temperature screening 'has been proven to be ineffective for identifying Covid-infected or infectious people'

Experts say that temperature screening ‘has been proven to be ineffective for identifying Covid-infected or infectious people’

Musical impresario Andrew Lloyd Webber was so taken with the idea that last summer he invested in high-tech ‘fever detection’ scanners that he intended to install in theatres. And just last week, political insiders claimed one idea being floated in Whitehall was to require everyone to log their temperature every day using the NHS Covid app.

But speaking to The Mail on Sunday’s Medical Minefield podcast, top international experts say temperature scanning is, at best, ‘futile’ and at worst, ‘dangerous’. Dr Jeremy Deuel, a Covid safety researcher from the University of Cambridge who has studied this, said: ‘Temperature screening has been proven to be ineffective for identifying Covid-infected or infectious people.’

In the US, where public health experts have been warning against the use of temperature scanners for months, Dr Monica Gandhi, an infectious disease specialist at the University of California San Francisco, says the measure is simply ‘for show’.

Nadhim Zahawi’s face shield is totally useless too 

Another bone of contention for scientists is the face visor, or face shield – worn by hairdressers and beauticians almost everywhere after the easing of the first lockdown.

Now even Government Ministers are adopting them.

Vaccine Minister Nadhim Zahawi chose to wear one instead of a mask while he was injected with his first Covid-19 vaccine earlier this month.

Vaccine Minister Nadhim Zahawi chose to wear a visor instead of a mask while he was injected with his first Covid-19 vaccine earlier this month

Vaccine Minister Nadhim Zahawi chose to wear a visor instead of a mask while he was injected with his first Covid-19 vaccine earlier this month

But experts have long warned that the plastic visors are virtually useless.

Last summer, scientists raised concern following an outbreak in a Swiss hotel. The infected hotel workers had all been wearing visors, but those who wore face masks in communal areas remained Covid-free.

At the time, Yann Hulman, a spokesman for Switzerland’s Federal Office of Public Health, said visors ‘do not serve as an alternative to masks’. In fact, Mr Zahawi’s choice of protective face gear was directly against his own Government’s advice on masks and visors.

Official guidance states face visors must not be worn instead of a mask, but ‘in addition’ to one. 

This is because visors fail to filter out viral particles that circulate in the air – the most common way in which Covid spreads is via inhalation.

Professor Julian Tang, a virologist at the University of Leicester, agrees. ‘It is very easy for virus particles to escape out the sides and underneath of a visor,’ he says. 

‘It is better than nothing, but I would say they do very little to protect you or others around you.’

Mr Zahawi, who in January said that the Government was ‘concerned’ about the lack of mask-wearing in supermarkets, declined to comment.

Last week, our GP columnist Dr Ellie Cannon raised concerns about the proliferation of temperature testing – which she dubbed ‘Covid theatre’ – a measure designed to appear to be doing something that doesn’t do anything at all.

She revealed that some medical staff even called temperature scanners ‘random number generators’ as they were so inaccurate. As a result, a number of readers wrote in with worrying stories. Perhaps the most concerning came from Jessica Smith, 24, who works in the offices of an engineering company in the North West with 1,000 employees.

She told us that there had been ‘hundreds’ of Covid cases at her workplace since September, despite the use of temperature checks.

‘Every day somebody comes round to our desks with a handheld temperature gun to scan the back of our neck,’ she said, adding that her bosses also require a twice-weekly rapid Covid test.

‘People would be in the office all week with normal temperatures, and then have their Covid test and test positive. And we don’t know when they contracted it.’

Another woman, an NHS nurse who asked to remain anonymous, said the inaccuracies of the temperature scanners used in her clinic are obvious. On many occasions they displayed such an extreme temperature the patient ‘should have been pronounced dead’. She added that many people with Covid may register a low temperature using a temperature scanner.

Traditional thermometers are held to the body, or placed in the mouth or another orifice, to directly measure body heat.

But temperature scanners – non-contact thermometers – work differently. These are either cameras or gun-type machines that contain sensors that pick up infrared energy emitted by the skin. The machine then uses a calculation based on this reading to estimate core body temperature.

These devices are widely used in industry – by maintenance workers, for instance, to help them locate burst pipes inside walls that may be leaking hot gas. But they are not recommended as medical tools.

In July last year, Public Health England issued a statement warning of the ‘problem’ of using temperature checks to spot Covid-19, describing the scanners as ‘not very accurate’.

In the same week, UK health watchdog the Medicines and Healthcare Products Regulatory Agency issued official guidance to manufacturers and suppliers of temperature check devices, warning them not to claim their product could spot Covid-19.

‘These products for temperature screening could put people’s health at risk,’ it stated, reiterating the point that scanners were ‘never designed’ for medical applications.

The main problem is that infrared energy is essentially a measure of surface temperature – and this is not a true reflection of body temperature. Being outside on a hot, or cold day, can alter skin temperature to the point the scanner would be rendered totally ineffective.

A recent Chinese study found even wearing a facemask can raise the temperature reading of a scanner by two degrees. In August – at the height of summer – the director of the US National Institute of Allergy and Infectious Diseases, Dr Anthony Fauci, announced his own organisation had banned temperature scanners, after a device read his temperature to be 39C – which would be a near-fatal fever.

He was, in fact, perfectly healthy, but had been in the blistering hot sunshine seconds before.

Musical impresario Andrew Lloyd Webber was so taken with the idea that last summer he invested in high-tech 'fever detection' scanners that he intended to install in theatres

Musical impresario Andrew Lloyd Webber was so taken with the idea that last summer he invested in high-tech ‘fever detection’ scanners that he intended to install in theatres

The most accurate measure of core body temperature is to take it via a thermometer under the armpit, under the tongue or inside the ear or rectum.

Studies have consistently shown that temperature checks fail to catch people infected with Covid-19. Most recently, a University of Zurich study of 84 Covid patients found that non-contact thermometers failed to detect temperatures in 83 per cent of Covid-positive patients, many of who did, in fact, have a fever. And during the 2003 SARS outbreak, scientists found that temperature checks at Australian airports, out of nearly two million people screened, failed to find a single case.

But the inaccuracy of the devices is only one part of the problem. Crucially, significant numbers of people with Covid won’t get so much as a sniffle, let alone a fever.

‘For this particular infection, symptom-based surveillance doesn’t work,’ says the University of California’s Dr Gandhi.

‘At the beginning of the pandemic, we thought, oh, this is going to be like other infections – you are going to feel unwell and that’s when you can spread it.

‘But then reports came back about at least 40 per cent of people having no symptoms, while still having the virus in their nose and being able to spread it to others.’

Dr Deuel warned relying solely on temperature checks for the all-clear, as many pubs, restaurants, bars and offices may do, would be a risky move as it can lull customers into a false sense of security, making them more likely to forgo social distancing.

Hospitals in the US have managed to limit the spread of infection among health workers without the use of temperature checks, according to Dr Gandhi.

She points out that, once the majority of the population is vaccinated, there will be no need for Covid-safe measures: ‘We’ll be immune.’

But until then, the philosophy should be to treat everyone as if they could be carrying the virus.

‘You need people distanced, and in face masks, keep the windows open or have other forms of ventilation,’ she says.

‘Testing can also be useful, but it’s a misunderstanding that healthcare workers in America were all getting swabbed and tested regularly. We weren’t. We were masking, distancing, ventilating, and we kept each other safe that way.’

Last year, scores of businesses, from fitness facilities and salons to pubs, restaurants and offices, required anyone who entered to have their temperature taken

Last year, scores of businesses, from fitness facilities and salons to pubs, restaurants and offices, required anyone who entered to have their temperature taken

A recent study published by Dr Gandhi and her team showed that businesses which adopted mass testing had no fewer outbreaks than those that simply adhered to strict mask-wearing, social distancing and ventilation requirements.

So if temperature checks are known to be an insignificant part of the puzzle, why are so many businesses using them?

Throughout the pandemic, the Government has updated guidance for workplaces regarding safety protocols for managing risk of Covid-19. Currently, all workplaces with more than five employees must carry out a full Covid-19 risk assessment, and share the results with their workforce. Local health and safety officials will then advise what changes need to be made in order to meet the Government’s requirements.

Such requirements include an increase in the frequency of handwashing and surface cleaning, with sinks or hand-sanitisers at exit and entry points. Two-metre distancing must be maintained ‘wherever possible’, which may involve redesigning workplaces and creating one-way systems.

Where social distancing isn’t possible, using screens or ‘barriers to separate people from each other’ is advised.

Employers are also required by law not to ask anyone with Covid-19 symptoms to come to work and remind workers to wear a face covering using signs.

Other suggestions include using back-to-back or side-to-side working and staggering arrival and departure times of employees.

But notably, temperature checks, or other symptom-tracking measurements, do not feature.

Having said that, thanks to the vague advice, you can forgive some business owners from thinking the more safety measures, the better.

The guidance advises employers to ‘reduce workplace risk to the lowest reasonably practicable level’ by taking ‘sensible measures’. Temperature testing, according to health and safety experts, may have been employed as a cost-saving exercise.

‘Some employers are using them as cheap alternatives to safety controls that are robust and effective,’ says Shelly Asquith, Health, Safety and Wellbeing Officer at the Trades Union Congress (TUC), which represents 48 trade unions and 5.5 million workers across the UK.

‘It’s much cheaper to check everyone’s temperature on the way in, rather than invest in proper ventilation and social distancing. But it creates a false sense of security.

‘It needs to be made very clear to employees that this is not a very reliable measure and it doesn’t mean they’re safe.’

Earlier this month, the body informed the Government of its concerns about the widescale use of temperature checks.

Recent research carried out by the TUC found although many workplaces were carrying out temperature checks, they were ‘scrimping’ on other legally required Covid safety measures.

‘One in four have told us Covid risk assessments haven’t even been carried out,’ says Asquith.

‘Usually the issue of cost is driving these decisions.’

There are signs that businesses are waking up to the idea that temperature checks may offer little in terms of Covid security. The British Beer and Pub Association confirmed that temperature testing did not feature in its safety guidance to venues, and EMD UK, which regulates gyms, had a similar approach.

Instead, simply asking customers or employees whether they’ve had any symptoms is far more useful, says Dr Deuel.

He adds: ‘Pubs and restaurants that think they’re doing anything by temperature testing people as they go in are not just wasting time, it can be dangerous to solely rely on that.’



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