Despite reports to the contrary, Ballarat has not set new records for the most new COVID cases recorded in the city in a single day.
Local media, including the ABC, incorrectly reported that 329 cases new cases on Monday was a record, subsequently broken by 389 cases on Tuesday.
While the new case numbers are alarmingly high, they are not records and highlight the changing face of the state government's health data.
So what is the record?
According to the state health department, Ballarat's record for the most new COVID cases in a day is 650 on January 7, 2022.
This figure is most likely an aberration.
While case numbers were high at the time, January 7 was the day the Victorian government introduced self-reporting of positive rapid antigen test (RAT) results.
"Most people who reported a positive rapid antigen test got that result earlier in the week, and reported it when the web form opened," the health department noted in a tweet on January 8.
This suggests that the record of 650 from January 7 included positive RATs recorded by people before that day, but were included in that day's total.
Even if we leave January 7 aside, the days that followed also yielded some high numbers:
- 482 on January 8,
- 463 on January 9,
- 470 on January 10, and
- 409 on January 12.
That would make Tuesday's total of 389 the sixth highest on record, according to the state health data.
So how was the 'mistake' made?
The huge influx of self-reported RATs took the state health department a while to sift through.
The department data dump on January 8 showed 251 cases reported the previous day.
That number was reported in local media and added into their ongoing graph.
But on the days that followed the health department retroactively updated the figures for January 7, and over the course of a few days it crept from 251 towards its current standing of 650.
This has happened regularly throughout the pandemic — late results are added to the correct date days later, sometimes even weeks or months later, which means the daily totals are continually being updated and re-calculated to ensure they are as accurate as they can be.
Unless reporters go back and continually check the updated raw data and not the figure they wrote down at the time, their calculations will be off.
So what is happening in Ballarat?
On May 9, Ballarat recorded 329 new cases of COVID-19 — the ninth highest daily total at the time.
In the days that followed, 389 cases have been recorded on both May 10 and May 11 — the equal sixth highest daily total to date.
The case numbers are alarming and add up to 1107 new cases in three days — the highest three-day total since January 10-12.
Ballarat has been averaging 278 cases a day for the past week.
By comparison, new cases dropped to an average of 130 a day towards the end of March, which was the lowest they had been since the start of the year.
