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The Office for National Statistics (ONS), have released the latest data from their COVID-19 Infection survey.
Prof Sheila Bird, Formerly Programme Leader, MRC Biostatistics Unit, University of Cambridge, said:
“Re-infection is defined as infection at 120+ days after previous infection.
“Omicron dominant period is defined as 20 December 2021 to 23 January 2021. ONS Community Infection Survey’s UK-wide data from 2 July to 19 December 2021 determine the pre-Omicron period.
“Results (see Table) echo round 17 of REACT-1 and are stunning. No wonder UKHSA hastily amended its reporting standard. Besides, change of variant on PCR-testing (previous infection, current infection) was surely a clear signal of re-infection. Columns 2 and 4 are for documentation only.
“The true comparators when duration differs for the two periods under consideration is re-infections per 100,000 days at-risk & re-infections with ct-value less than 30 per 100,000 days at-risk, see columns 3 and 5.
“Cycle-threshold value (ct-value) less than 30 is a proxy for higher viral load and hence higher infectiousness. Notice that 76% of re-infections in the Omicron-dominant era had ct-value less than 30 versus 60% in the pre-Omicron era. Hence, the relative infection rate is even higher at 20:1 for low ct-value re-infections than for all re-infections at 15:1.
“Fifteen-fold greater re-infection rate in the Omicron-dominant era is itself massive, as previously signalled in the REACT-1 surveillance. Of course, ONS Community Infection Survey, being longitudinal, does not rely on self-report because its participants undergo repeat-testing.
“However, testing from 2 July 2020 does not account for those who were ill from SARS-CoV-2 during wave 1 when there was not widespread community testing.”
All our previous output on this subject can be seen at this weblink:
www.sciencemediacentre.org/tag/covid-19
Declared interests
None received.