Although we know that vaccines provide good protection against becoming seriously ill with COVID-19, it’s still possible to catch and pass on the virus even if you’ve been double jabbed, leaving children, unvaccinated adults and those who are less well-protected by the vaccine at risk.
Results from our ‘pingdemic’ survey
Over one week in July, we asked contributors to the ZOE COVID Study app to confidentially tell us whether they’d been ‘pinged’ and told to self-isolate by anyof the UK contact tracing apps. More than 750,000 of you responded - thank you!
Next, we compared people who said they had been ‘pinged’ with those who had not, to see who went on to report a positive test.
We found that only 2.4% of fully vaccinated participants who were ‘pinged’ by either the NHS COVID-19 App or Protect Scotland App app and who felt physically welll went on to test positive for COVID.
Figure 1: Positivity rate in people ‘pinged’ and ‘not pinged’ according to whether or not they had any symptoms of COVID-19
People who reported being ‘pinged’ by the NHS COVID-19 app in England and Wales were around four times more likely to have COVID-19 than someone who wasn’t.
However, participants who got ‘pinged’ by the Protect Scotland app were around 10 times more likely to have COVID-19 than someone who wasn’t.
This suggests that the Scottish app is doing a better job of alerting those who are likely to be positive after coming into contact with an infected person than in the other two nations.
Figure 2: Relative risk of being positive of COVID-19 if pinged across NHS COVID-19 app and Protect Scotland app
We also discovered that younger people who were told to self-isolate after being ‘pinged’ were more likely to test positive compared to older age groups. And we found that unvaccinated participants were much more likely to test positive for COVID if they were ‘pinged’ compared with partially vaccinated and fully vaccinated users.
Figure 3: Positivity rate in ‘pinged’ and ‘not pinged’ people by vaccination status
Should you self-isolate if you get ‘pinged’?
Overall, our findings tell us that a combination of symptom monitoring and contact tracing is more accurate when it comes to identifying who should self-isolate than ‘pinging’ alone, especially for people who have been vaccinated.
Even though restrictions are easing, the only way out of the pandemic is to bring down the number of infections while protecting as many people as possible through vaccination.
The message is clear: if you get ‘pinged’ and feel unwell, you should stay home and get tested to protect your loved ones and the community around you - even if you’ve been double vaccinated.
Professor Tim Spector, lead scientist at ZOE COVID Study and professor of genetic epidemiology at King’s College London, says,
“While I welcome efforts to address the ‘pingdemic’, cases are still very high and our research shows that whatever your vaccination status, if you have one of possible 20+ COVID symptoms recognised by ZOE, you should be cautious, self isolate and get a test.”
Our findings also make it even more important that the Government expands the current list of COVID-19 symptoms beyond the ‘classic three’ of cough, fever and loss of smell, to help raise public awareness of the full range of symptoms of infection.