Deaths from COVID-19 used to peak three weeks after cases, although University of NSW mathematician and pandemic modeller, associate professor James Wood, said this had been closer to two weeks with the Omicron variant, which has been dominant in Australia throughout 2022.
After cases peaked in mid-to-late July, Wood said the current wave “should have just passed [its] peak-in-mortality”.
However, with more COVID deaths occurring outside public hospitals, and so being tallied by other agencies such as births, deaths and marriages, the time when a virus death is reported by state health departments is less uniform than in earlier waves of infection.
“The level of case reporting is also not as high as it used to be, so the level of known cases relative to the number of deaths we see may not necessarily match up,” Lang said.
In February, the working group warned Australia would experience excess annual mortality, or more overall deaths from all causes than expected, in 2022, unless there was a significant reduction in cases. Lang said excess mortality was now expected.
David Muscatello, an associate professor in infectious diseases epidemiology at the University of NSW, agreed this was a foregone conclusion, mostly due to high COVID-19 deaths.
The recent wave has been driven by the BA.4 and BA.5 Omicron sub-variants, known to evade immunity gained from earlier infection or vaccination. It has also seen a higher proportion of older people catching the virus, which has affected the death toll.
Of the 164 people NSW virus deaths reported in the week ending July 30, 124 were aged 80 and over, data from NSW Health’s latest surveillance report showed. Sixty-five were in their 90s and 79 were living in residential aged care.
Old age is a risk factor for severe COVID-19.
However, the return of school has shifted the outbreak’s demographics, with NSW data showing cases now rising among 10 to 19-year-olds.
Cases in aged care also appear to have peaked: the number of homes with an active outbreak fell from 1064 to 952 last week, according to federal government weekly reports.
“The age profile of people who are getting infected does seem to change somewhat as each [virus] lineage comes along,” Muscatello said. However, I believed the volume of cases was what was driving Australia’s death toll.