Thursday, July 20, 2017

Week 28: Hong Kong's Flu Activity Increases To `A Very High Level'.

Credit HK Flu Express - Week 28











#12,625

It is rare that we should find ourselves talking this much about seasonal influenza in mid-July, but this summer's surge of flu in South East China (see yesterday's Macao, Hong Kong & Guangdong Province All Reporting Heavy Flu Activity) is more than just a little unusual.
Hardest hit (at least, based on reporting), has been Hong Kong, which after declaring their winter flu season over in mid-April (see chart above), was forced to reinstate their enhanced surveillance for severe seasonal influenza system in early May.
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 May, Hong Kong has reported an additional 312 severe cases and 208 deaths.
In the 7 days since the last (week 27) update, Hong Kong reported another 76 severe flu cases, and 53 deaths. Included are 5 severe pediatric cases, including 1 death.
Some excerpts from this morning's HK Flu Express, then I'll return with a bit more.
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 19, 2017)

Reporting period: Jul 9 – 15, 2017 (Week 28)

  • The latest surveillance data showed that the local influenza activity further increased to a very high level in the past week. It is foreseen that the influenza activity will remain at a very high level in the coming weeks.
  • 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 19, 297 severe cases (including 205 deaths) were recorded. Separately, 15 cases of severe paediatric influenza-associated complication/death (including three 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 get the vaccination as soon as possible 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)

Laboratory surveillance, 2013-17

Among the respiratory specimens received in week 28, 2746 (40.66%) were tested positive for seasonal influenza viruses, including 107 (1.58%) influenza A(H1), 2549 (37.75%) influenza A(H3), 73 (1.08%) influenza B and 17 (0.25%) influenza C.
The percentage of respiratory specimens tested positive for seasonal influenza viruses last week was 40.66%, which was higher than 35.87% recorded in the previous week (Figure 2). Among the influenza viruses detected in the last week, the proportions of A(H3), A(H1), B and C were 92.8%, 3.9%, 2.7% and 0.6% respectively.

(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 312 severe cases (including 208 deaths) were recorded cumulatively (as of Jul 19) (Figure 9). These included:

  • 297 cases (including 205 deaths) among adult patients aged 18 years or above. Among them, 257 patients had infection with influenza A(H3N2), 21 patients with influenza A(H1N1)pdm09, 11 patients with influenza B and eight patients with influenza A pending subtype. 101 (34.0%) were known to have received the influenza vaccine for the 2016/17 season. Among the 205 fatal cases, 85 (41.5%) were known to have received the influenza vaccine. In the winter season in early 2017, 66 adult severe cases (including 41 deaths) were filed.
  • 15 cases (including three deaths) of severe paediatric influenza-associated complication/ death. Thirteen (86.7%) cases did not receive the influenza vaccine for the 2016/17 season. To date in 2017, 23 paediatric cases (including four deaths) were filed.
Enhanced surveillance for severe seasonal influenza (Aged 18 years or above)
  • In week 28, 72 cases of influenza associated ICU admission/death were recorded (including 50 deaths), which was higher than 39 cases (including 16 deaths) recorded in week 27. In the first 4 days of week 29 (Jul 16 to 19), 38 cases of influenza associated ICU admission/death were recorded, in which 25 of them were fatal.
Surveillance of severe paediatric influenza-associated complication/death (Aged below 18 years)
  •  In week 28, three cases of severe paediatric influenza-associated complication/ death (including one fatal case) were reported. In the first 4 days of week 29 (Jul 16 to 19), two cases of severe paediatric influenza-associated complication were reported. The case details are as follow: 
http://www.chp.gov.hk/files/pdf/fluexpress_web_week28_20_7_2017_eng.pdf

 (Continue . . . .)
 
Although the percentage of fatal cases known to have received a flu vaccine is fairly high at 41.5%, Hong Kong ramps up their annual flu vaccination program in the fall, focusing primarily on high risk groups like the elderly and pregnant women. 
With such a late season surge, presumably some of protective effects of last year's vaccine have begun to wane, particularly among the elderly. 
Add in that the highest risk groups are the ones most apt to get vaccinated, and the growing diversity among the H3N2 subtype (see Eurosurveillance: Emergence Of A Novel Subclade Of Seasonal A/H3N2 - London), and this number - while disappointing - isn't all that surprising. 

While flu vaccines are still available, next fall's flu vaccination program is set to begin in October (see Seasonal influenza vaccination programmes in 2017/18 to be launched), and will be targeted towards the following priority groups.




Lastly, although hardest hit have been those over 65, this morning the CHP is reporting on yet another severe pediatric case.




The Centre for Health Protection (CHP) of the Department of Health is today (July 20) investigating a case of severe paediatric influenza A infection.
 
"The local seasonal influenza activity remains at a very high level and it is expected to remain very active in the coming weeks. We strongly urge the public, particularly children, the elderly and chronic disease patients, to adopt strict personal, hand and environmental hygiene both locally and during travel in the summer," a spokesman for the CHP said.
 
The 1-year-old baby boy, with good past health, has developed fever, cough and runny nose since July 12. He was taken to the Accident and Emergency Department of Kwong Wah Hospital on July 17 and was admitted for management on the same day. He was subsequently taken to a private hospital yesterday (July 19) for further treatment and was later transferred to the Paediatric Intensive Care Unit of Prince of Wales Hospital on the same day as his condition deteriorated.
The clinical diagnosis was influenza A infection complicated with severe pneumonia and he is now in stable condition.

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