‘Notification figures better reflect Covid situation’

People who have been following the Centre for Health Protection’s (CHP) daily Covid infection numbers may have noticed the introduction of a new set of figures that authorities say paints a more accurate picture of the day-to-day situation than the now-cancelled “preliminary positive” tally.

The new “notification figure” adds up all the cases the CHP has been informed about over the past 24 hours from both public and private laboratories, and covers both preliminary positive and confirmed cases.

This differs from the newly-confirmed cases, which are all the tests conducted by the Department of Health (DH) or the Hospital Authority (HA). The lion’s share of these are confirmatory tests conducted on samples that had previously been deemed as “preliminary positives” based on tests from private labs.

Samples taken at Community Testing Centres, for example, are first tested by a government-approved list of private contractors, before they are confirmed in a government lab.

That means the confirmed infection figures don’t necessarily reflect cases that have emerged during the previous day.

Due to the exponential surge in Covid cases, there have been an increasing number of backlogged cases, so the current day’s confirmed cases could have been of samples taken from the patient days ago.

Previously, the CHP had given “preliminary positive” figures that accurately reflected how many people had actually tested positive over the past day.

But the increasing delays meant that figure kept ballooning as overwhelmed government labs were no longer able to clear the backlog quickly, giving a skewed picture of the actual Covid situation.

“The current situation is that at every stage there are some delays. Some preliminary positives have remained preliminary positives for many days but can still not be confirmed. So that does not reflect the speed,” the CHP’s Chuang Shuk-kwan explained this week.

“So we think that in order to look at the recent trend, the daily trend, we need to have another figure that can reflect the latest situation, so we use a daily number of notifications.”

Health authorities are given information from the Hospital Authority and private laboratories virtually in real time, Chuang said, and are as such able to give a more accurate picture day-to-day of the pandemic situation.

Infectious disease expert Leung Chi-chiu said the notification figures adopted by the CHP can to some extent show that Hong Kong was still facing an exponential increase in the number of cases.

“Confirmed cases by the CHP may not be accurate, and the number of cases preliminary reported by the laboratory within 24 hours should have been a better index,” Leung told RTHK.

“Unfortunately, we have a very long delay in the turnout for the laboratory testing. Some of these positive specimens could have been submitted over a week ago… This may affect our assessment of the epidemic situation. It’s best if we know the number of positive specimens submitted by the day. This may be a more reliable reflection of disease trend.”