The effect of this year’s vaccine mismatch due to a `drifted’ H3N2 virus has been keenly felt across the Northern Hemisphere, but perhaps no more so than in Hong Kong which has seen a doubling of severe cases and a tripling of deaths over last season.
While the flu season is slowly winding down for most of us, Hong Kong continues to report new deaths daily, and historically often endures a second peak of influenza in the summer (see Hong Kong Girds For More Flu).
HK’s recent history of `Twin Peaks’ of influenza– Credit Flu Express
Although the Northern Hemisphere flu vaccine was a bust this year, the re-formulated Southern Hemisphere vaccine is due out in the next few weeks, and it includes a strain that should match the `drifted’ H3N2. In an unusual move, Hong Kong’s CHP announced last February they had ordered a limited supply of the New Southern Hemisphere flu vaccine (SH SIV), which was expected to arrive in April.
With a population of over 7 million, of which roughly 13% (1 million) are over the age of 65, and only about 100, 000 doses of this new vaccine expected to be available, Hong Kong has had to make the kind of vaccine prioritization decisions that we might expect to see in the opening months or year of a pandemic; deciding who gets part of limited resource.
Since 1.7% of the city’s population – those 85 and older – comprise 53% of this year’s influenza deaths, that cohort will have top priority when the new vaccine arrives (see HK Demographics Chart). Whatever vaccine remains after this first tier is served will be used for those aged 75-84, although depending on uptake, supplies are likely to fall short of that cohort’s needs.
Despite the original April target delivery date, it now appears this vaccine won’t be deployed until May or June.
This from Hong Kong’s CHP:
The Controller of the Centre for Health Protection (CHP) of the Department of Health (DH), Dr Leung Ting-hung, today (March 20) welcomed the recommendations on the use of the southern hemisphere seasonal influenza vaccine (SH SIV) by the CHP's Scientific Committee on Vaccine Preventable Diseases (SCVPD) in Hong Kong.
"The SH SIV contains the currently predominant influenza A/Switzerland/9715293/2013 (H3N2)-like virus strain. Based on the risk assessment, the SCVPD recommends the elderly to be the priority group to receive the SH SIV to protect them from the possible summer influenza season. Besides, the SCVPD recommends all persons living in residential care homes for the elderly (RCHEs) to receive the SH SIV for the prevention of influenza outbreaks," Dr Leung said.
Epidemiology and priority groups
The SCVPD convened two meetings respectively on February 17 and this morning to examine the latest local, neighbouring and overseas epidemiology of seasonal influenza in this winter season, and assess the risk of various groups. It also studied issues related to the use of the SH SIV, including vaccine composition, vaccine effectiveness, any adverse effects and priority groups.
"The elderly, particularly the very old elderly, are the most vulnerable in this season as reflected by the high proportion of severe and fatal cases affecting the elderly, the high influenza admission rate among the elderly and the high proportion of RCHEs having outbreaks of influenza-like illness (ILI)," Dr Leung explained.
As of noon of March 16, among influenza-associated admissions to intensive care unit or deaths in adults aged 18 or above under the enhanced surveillance with public and private hospitals since January 2, 86.0 per cent were the elderly aged 65 or above (41.4 per cent aged 85 or above, 31.3 per cent aged 75 to 84, 13.2 per cent aged 65 to 74). As for deaths, 93.5 per cent were those aged 65 or above (53.0 per cent aged 85 or above, 31.7 per cent aged 75 to 84, 8.8 per cent aged 65 to 74).
The influenza-associated public hospital admission rate for the elderly aged 65 or above peaked at 5.54 cases per 10 000 persons in the last week of January, which is the highest since 2005, and has remained elevated so far. Institutional ILI outbreaks in this season mainly occurred in RCHEs (over 40 per cent).
"The SH SIV, when available, may be given by phases starting from the oldest age group, such as those aged 85 or above, in the community first as they are at higher risk of developing severe illness after infecting influenza. Most of them also have pre-existing underlying illnesses predisposing them to severe illness," Dr Leung remarked.
The DH has procured about 100 000 doses of SH SIV from a vaccine supplier by contract upon completion of the tender in accordance with government procurement procedures and requirements. As they are expected to be delivered in late April or early May, the vaccination programme is preliminarily planned to be conducted in May and June.
"Vaccination will be provided to priority groups, i.e. the elderly, under the existing Government Vaccination Programme (GVP) for free. As part of the GVP, the Residential Care Home Vaccination Programme will provide the SH SIV to RCHEs' residents through enrolled Visiting Medical Officers to which an injection fee of $50 per dose will be reimbursed. We will work out the logistics with RCHEs shortly," Dr Leung said.
Regarding the elderly in the community setting, the CHP is working closely with the Hospital Authority on the implementation. The elderly will receive the SH SIV by phases in public hospitals and clinics, with those of higher age to be vaccinated first, followed by other elderly in the next.
Ends/Friday, March 20, 2015
Issued at HKT 13:33