• Behavioural scientists warn that coronavirus testing could lead potentially infectious people to follow those testing negative out of isolation.
  • Warn that careful managing of testing is required to avoid further outbreaks.
  • World Health Organization advise testing and isolation as the best way to prevent COVID-19 infection.

Mass public testing for coronavirus could have a negative impact on compliance with social isolation and other protective behaviours, scientists have warned.

Professor Madelynne Arden at Sheffield Hallam University, and Professor Christopher Armitage at the University of Manchester, wrote of their concerns to England’s chief medical officer Chris Whitty, Health Secretary Matt Hancock and others.

The behavioural scientists say there is a risk of people who have had coronavirus, and are likely to have immunity, returning to normal life, and being followed by others who have not.

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In an email they told the officials: “News that home/community testing for COVID-19 will soon be possible seems really positive, and as a family who developed mild symptoms we, like others, would be keen to have this test to know if we have immunity.

“However, as professors, HCPC-registered health psychologists and experts in behavioural science, we are very concerned about the likely effect of mass public testing for COVID-19 on people’s reactions to public health messages to stay at home and socially isolate.

“It may well be that these issues are already being given careful consideration, in which case we apologise for taking up your valuable time, but we felt compelled to write in case they are not.”

Another concern is that people who are fed up with isolation will go out and simply claim to have had the infection.

The scientists also raise concerns that people who are fed up with being in isolation will claim to have had the infection in order to get out and about.

The professors add: “Making tests easily available in the community could therefore have detrimental effects on public social isolation and therefore on the spread and containment of COVID-19.”

The scientists say social norms to isolate are extremely important, pointing to the weekend of March 21/22, when a large number of people were seen out and about despite government guidance.

Professor Chris Whitty © Leon Neal/PA
Professor Chris Whitty © Leon Neal/PA

The email explains: “Clearly the Government expected that people would make rational assessments of personal/family risk and that, once they realised that physical separation would not be possible in a tourist location, they would turn around and go back home.

“But they did not.

“A likely reason for this seemingly contrary behaviour is that other people being out and about created a social norm that this was OK and safe: ‘if other people are doing it, then it’s probably safe for me as well’.”

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However, the letter does not advise against mass testing, instead urging careful planning on how it will be managed to avoid these potential issues.

The email was also sent to shadow health secretary Jon Ashworth, Public Health England chief executive Duncan Selbie and other officials dealing with the pandemic.

Although the letter addresses the possible outcomes of allowing people testing negative for COVID-19 to come out of isolation, the World Health Organization (WHO) explicitly advises mass testing to help stop the spread of the coronavirus.

"The most effective way to prevent infections and save lives is breaking the chains of transmission, and to do that, you must test and isolate," said Dr Tedros Adhanom Ghebreyesus, director general of WHO at a press conference last week.

"You cannot fight a fire blindfolded and we cannot stop this pandemic if we don’t know who is infected.


"Once again, our key message is: test, test, test."

Can I get the coronavirus twice?

There have been a few stories in the press of people apparently being re-infected by the coronavirus SARS-CoV-2. These people reportedly became infected and hospitalised, and then were sent home once they’d tested negative for the virus. Then, days or weeks later, they tested positive again.

But this doesn’t necessarily mean that they caught the coronavirus twice.

First, during recovery from infection, a person may have very low amounts of the virus remaining in their body – low enough that our tests can’t accurately detect it. In this case, the person may be sent home on the assumption that they’re virus-free. However, their body may still be fighting the virus, and a resurgence of the virus (and symptoms) can occur, resulting in a positive test. In this case, it would just be one protracted infection, not a re-infection.

Second, we know that in most people, SARS-CoV-2 generates a strong response from the immune system. With the related coronavirus SARS-CoV, this response creates an immune memory of the virus that prevents re-infection for one to two years, and it’s likely that this is also the case for the new virus. SARS-CoV-2 also has a fairly low mutation rate, which means that it (hopefully) won’t change enough that our immune system no longer remembers it (this is what the flu virus does and why we need a new jab every year).

If this all turns out to be true, then it would suggest that re-infections are unlikely and that the cases in the news reflect testing sensitivity. However, SARS-CoV-2 is so new that we won’t know for sure until we’ve found out just how protective our immune response to the virus is, and how long it lasts.

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Alexander McNamaraOnline Editor, BBC Science Focus

Alexander is the former Online Editor at BBC Science Focus.