The pingdemic could have prevented cases soaring to 100,000 a day, an expert has said.
In July, Health Secretary Sajid Javid suggested cases could rise to more than 100,000 a day in the summer after all restrictions were eased on July 19.
However, after so-called Freedom Day, daily cases have not been higher than 45,000.
Professor Graham Medley said that in July data was pointing towards cases heading towards 100,000 per day, but the figures did not materialise, which modellers “do not have a good explanation” for.
The member of the Scientific Pandemic Influenza Group on Modelling (SPI-M) said the pingdemic may have contributed to cases flatlining after restrictions eased as networks of transmission were “broken”.
He also warned that if people return to pre-pandemic levels of mixing before Christmas then transmission rates could pick up “a lot”.
Asked about the prediction of case numbers over summer, he said: “Up until about July 15, we were seeing a trajectory that was heading towards 100,000 cases a day.
“Then, something happened on July 15, and to be completely honest, I don’t think any of us on Spi-M, any of the modellers, have a very good explanation for what happened.
“The pingdemic may well have played quite a role in that, in the sense of it asked people to isolate not if they were infected but if they had been in contact with someone who was infected and, as a result, those people who then isolated were at lower risk of infections, so that may well have had a role in terms of breaking up the networks along which Covid was transmitting at that point.
“For some reason, the exponential growth up until that point just turned off and we have been pretty much flat in England ever since, which none of the models predicted – but as we said at the time there is uncertainty because we don’t know what people are going to do.
“I think the impact of the pingdemic was not so much on the people who were infected being asked to isolate, it was on the people who were not infected, but who were contacting people who were infected so it broke up those networks of transmission.”
Prof Medley warned that there is still potential for another peak of cases.
“There is still potential for another peak, although it will not be as high, we think, as previous peaks, but it’s still there if people go back to full contact rates,” he said.
“The CoMix study suggests that we are still making a half or less than half the number of contacts that we make without being in a pandemic, so people are still being quite conservative about what they do
“If everyone went back to full mixing, for example, in the months leading to Christmas, then we could well see the transmission rates pick up quite a lot.”