The Centre for Health Protection today announced that according to the latest surveillance data, local seasonal influenza activity continued to increase in the past week and exceeded the baseline thresholds, indicating that Hong Kong has entered the flu season.

From the latest surveillance data, among the respiratory specimens, the weekly percentage of detections that tested positive for seasonal influenza viruses has increased from below 1% in the first week of March to 9.89% in the week ending April 1.

The majority of positive detections in that period were influenza A H1 and influenza A H3, with very low influenza B activity.

Of note, past epidemiological data showed that children and adults aged from 50 to 64 years were relatively more affected in seasons dominated by influenza A H1.

The overall admission rate with principal diagnosis of influenza in public hospitals has also continued its rising trend, from 0.01 per 10,000 population in the first week of March to 0.25 per 10,000 population in the week ending April 1.

There were 12 institutional influenza-like illness outbreaks reported in the week ending April 1 compared with one to two outbreaks in March.

The centre will issue letters to doctors, hospitals, institutions and schools to appeal for heightened vigilance. Schools are reminded to take additional measures, including actively checking the body temperature of all students every day when they arrive at school.

As of April 2, about 1.53 million doses of seasonal influenza vaccination (SIV) had been administered through the Government Vaccination Programme, the Vaccination Subsidy Scheme and the Seasonal Influenza Vaccination School Outreach (Free of Charge) Programme 2022/23, representing a 24% rise over the same period in the previous year.

The influenza vaccination coverage rate for seniors aged 65 or above was 47% whereas that for toddlers and adolescents aged six months to below 18 years was 40%, indicating that most people in different age groups have yet to receive SIV.

Meanwhile, a slight increase has been observed recently in positive nucleic acid test laboratory detections newly recorded for COVID-19 as well as per capita viral load in relation to COVID-19 from sewage surveillance.

The centre urged the public to complete the recommended dosage of COVID-19 vaccines and SIV as early as possible for better protection.