Explainer: A look at Hong Kong's worst COVID-19 wave, and mainland-aided fight

HONG KONG -- Hong Kong has reported a rapid increase in COVID-19 infections since the fifth wave of the epidemic began. On Tuesday, it registered 32,597 new cases and 117 more deaths.

During the week from Feb 23 to March 1, Hong Kong reported a daily average of 23,961 cases, compared with 6,227 cases in the previous week.

Why are the cases rising so rapidly? What are Hong Kong's anti-epidemic measures? And how is the Chinese mainland beefing up Hong Kong's defense in this critical stage? Here is what you need to know.

Why are cases jumping recently?

An important factor is that the Hong Kong Special Administrative Region (HKSAR) government changed the procedure for confirming cases.

Before the change, a preliminarily confirmed case required a positive retest before it would be recorded as a confirmed case, and the process would take three to four days. After the change, re-testing is no longer needed. Besides, the conditions for confirmation have been simplified, the results of residents' rapid self-tests are recognized by the HKSAR government.

"The current surge in the number of confirmed cases is also related to the fact that the number of cases was not fully reflected in the previous tally," said Ming Wai-kit, an assistant professor at the Department of Infectious Diseases and Public Health, City University of Hong Kong.

Before the simplification of procedures, many asymptomatic and mildly ill patients failed to be tested because they could only be sampled at a medical facility, and such cases were not included in the statistics, he told Xinhua.

There is still some doubt as to whether the number of confirmed cases are all true positives, which will ultimately need to be determined after Hong Kong's mass mandatory testing, Ming said.