Hong Kong's Late Season Flu Continues To Rise

Credit HK Flu Express

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While Taiwan's out-of-season summer flu surge appears to have peaked, the same can't be said for Hong Kong, which is entering its third month of increased flu activity with an unusual number of flu-related deaths. 

On May 5th, several weeks after Hong Kong's winter flu season appeared to be  over, severe cases of influenza began showing up in local hospitals (see Hong Kong CHP Reports A Late Season Flu Surge), forcing the Centre for Health Protection to reinstate their enhanced surveillance for severe seasonal influenza system.

While Hong Kong is known for having a biphasic or `double peaked’  flu season, their heaviest activity is usually from February–April with a less severe resurgence in mid-to-late summer (cite).

Hong Kong's `regular' flu season - which ran from February through April this year - ended with 74 severe cases and 42 deaths. Since it unexpectedly re-awoke in early May, Hong Kong has reported an additional 236 severe cases and 157 deaths.

Despite their severity, and unusual timing, all of these cases are reported to be due to seasonal flu viruses, mostly H3N2.  A reminder that it doesn't take a novel flu to be life threatening.

 Some excerpts from today's Flu Express (week 27) follow:

FLU EXPRESS
 
Flu Express is a weekly report produced by the Respiratory Disease Office of the Centre for Health Protection. It monitors and summarizes the latest local and global influenza activities.

Local Situation of Influenza Activity (as of Jul 12, 2017)

Reporting period: Jun 2 – Jul 8, 2017 (Week 27)

• The latest surveillance data showed that the local influenza activity has further increased and was at a high level.
•  The Centre for Health Protection (CHP) has collaborated with the Hospital Authority (HA) and private hospitals to reactivate the enhanced surveillance for severe seasonal influenza cases (i.e. influenza-associated admissions to intensive care unit or deaths) among patients aged 18 or above since May 5, 2017. As of Jul 12, 223 severe cases (including 155 deaths) were recorded. Separately, 13 cases of severe paediatric influenza-associated complication/death (including two deaths) (aged below 18 years) were recorded in the same period.
• Apart from adopting personal, hand and environmental hygiene practices against respiratory illnesses, those members of the public who have not received influenza vaccine may still get the vaccination for personal protection.
•   Influenza can cause serious illnesses in high-risk individuals and even healthy persons. Given that seasonal influenza vaccines are safe and effective, all persons aged 6 months or above except those with known contraindications are recommended to receive influenza vaccine for personal protection.

 (SNIP)

Surveillance of severe influenza cases

(Note: The data reported are provisional figures and subject to further revision)

Since the activation of the enhanced surveillance for severe influenza infection on May 5, 2017, a total of 236 severe cases (including 157 deaths) were recorded cumulatively (as of Jul 12) (Figure 9). These included:

• 223 cases (including 155 deaths) among adult patients aged 18 years or above. Among them, 189 patients had infection with influenza A(H3N2), 18 patients with influenza A(H1N1)pdm09, nine patients with influenza B and seven patients with influenza A pending subtype. 73 (32.7%) were known to have received the influenza vaccine for the 2016/17 season. Among the 155 fatal cases, 63 (40.6%) were known to have received the influenza vaccine. In the winter season in early 2017, 66 adult severe cases (including 41 deaths) were filed.
• 13 cases (including two deaths) of severe paediatric influenza-associated complication/ death. Twelve (92.3%) cases did not receive the influenza vaccine for the 2016/17 season. To date in 2017, 21 paediatric cases (including three deaths) were filed.

Enhanced surveillance for severe seasonal influenza (Aged 18 years or above)

• In week 27, 39 cases of influenza associated ICU admission/death were recorded (including 16 deaths), which was higher than 33 cases (including 24 deaths) recorded in week 26. In the first 4 days of week 28 (Jul 9 to 12), 36 cases of influenza associated ICU admission/death were recorded, in which 27 of them were fatal.

Surveillance of severe paediatric influenza-associated complication/death (Aged below 18 years)

•  In week 27, there were no cases of severe paediatric influenza-associated complication/ death. In the first 4 days of week 28 (Jul 9 to 12), three cases of severe paediatric influenza-associated complication were reported. The case details are as follow:

Credit Flu Express

(Continue . . . )

Elsewhere in the world, we are seeing fairly seasonable flu reports, with cases increasing in Australia (as is expected in July), but no other areas reporting unusual activity.

We will, however, keep a close eye flu activity in Hong Kong and elsewhere over our summer, as they may provide us with some hint as to what to expect next fall in the Northern Hemisphere.