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How to interpret the 15,152 surge in COVID-19 new cases of February 12

China reported 15,152 new cases for February 12, in an apparent 600% surge over the preceding day. However, this spike does not represent a change in the trend.

In fact, 13,332 of these new cases are clinically (rather than laboratory) confirmed cases, reported for the first time as an effect of a change in how cases are diagnosed and reported in Hubei province starting on February 12. Previously, these cases were counted as “probable” or “suspected” cases.

Of the 15,152 new cases reported, only 1,820 are new laboratory confirmed cases (1,508 in Hubei province and 312 elsewhere in China).

These 1,820 new laboratory confirmed cases actually represent a decline of 26% over the preceding day (when 2,467 cases, all laboratory confirmed, were reported).

Change in how cases are diagnosed and reported

Starting on February 12, in the Hubei province only, a trained medical professional can classify a suspected case of COVID-19 as a clinically confirmed case on the basis of chest imaging, rather than having to have a laboratory confirmation.

This allows clinicians to move and report cases more quickly - not having to wait for lab confirmation - ensuring that people get adequate care faster and also allowing for public health responses - such as contact-tracing - to be initiated.

Redistribution of the surge in new cases

Most of these 13,332 clinically confirmed cases relate to a period going back days and weeks, and were all retrospectively reported as cases on a single day, but they need to be redistributed over the entire preceding period.

WHO is currently working with Chinese health officials to see exactly how those numbers are spread out across those days and weeks.

Worldometer is awaiting the result of this analysis before making adjustments to the historical graphs and tables.

In the rest of the world, laboratory confirmation for reporting is still required, and WHO will continue to track both laboratory and clinically confirmed cases in Hubei province.

Caution when looking at numbers

WHO warned, in its February 13 press conference, that we need to be cautious when drawing conclusions from daily reported numbers and when interpreting any extremes, be in the incubation period (a study had reported a range of up to 24 days), be it in daily numbers.

We must take all numbers into account and look at them seriously, but we must also always try to interpret what those numbers mean and not react directly to the number itself without proper context, WHO said.

FEBRUARY 14 UPDATE:

Subsequently, the National Health Commission of China, in its February 14 official report, deducted 1,043 previously reported cases from the total for February 12 in Hubei Province due to "repeated statistics." (an error of duplicate reporting). Accordingly, the increase for Feb. 12 has been adjusted in our case statistics to 14,109 new cases rather than the 15,152 initially reported.

Sources

  1. WHO Press Conference (Video) - WHO, February 13, 2020
  2. Update on new coronavirus pneumonia situation as of 24:00 on February 13 - National Health and Health Commission of China, February 14, 2020