The Centre for Health Protection announced on Thursday the summer influenza season had ended and warned that its winter equivalent is approaching with the weather taking a decidedly colder turn in recent days.

The Department of Health said influenza activity had been decreasing over the past few weeks and in recent weeks fell to below the baseline level.

Centre controller Edwin Tsui said Hong Kong entered the summer influenza season in early September and that the season peaked in middle to late October.

Latest data for the most recent week, he said, showed the percentage of respiratory specimens testing positive for seasonal influenza virus was 4.08 percent and that the influenza-associated admission rate in public hospitals was 0.23 cases per 10,000 population, both of which were lower than the baseline levels of 4.94 percent and 0.27 cases.

The end of the summer influenza season at this time meant that the two seasons had not, he added, overlapped.

In the summer season, the predominance of influenza A led to 25 severe paediatric and 507 severe adult cases and caused 342 deaths, with most of the fatalities involving people who had not undergone vaccination.

More than 1.91 million doses of seasonal flu vaccine have been administered so far, but coverage among children aged between six months and under two years remains low at about 22 percent, the department said.

It called on residents to get the flu jab for the winter season as soon as possible, especially those who are expecting, the elderly, children and chronically ill people.