BSL-3 – Credit CDC PHIL
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While a heated debate continues (see CIDRAP article
H5N1 researchers question proposed HHS funding framework) over the future of research that seeks to enhance the transmissibility, pathogenicity, or host range of the H5N1 virus - there are many labs around the world that are called upon to deal with the virus in a more routine way.
There are laboratories that screen influenza virus samples in regions where H5N1 is endemic, labs that that test samples taken directly from livestock or human subjects suspected of H5N1 infection, along with other research facilities not engaged in `enhanced’ H5N1 research.
Although laboratory bio-safety protocols tremendously lower the risk of accidental infection, that risk is not zero.
Which is why today it was announced that a special advisory committee in Hong Kong has recommended certain high risk laboratory technicians be offered an H5N1 vaccine, to further reduce those risks.
From this release we also gain some insight into Hong Kong’s pandemic strategy, which eschews the stockpiling of a pre-pandemic vaccine (which may not be effective against a newly emerging pandemic strain), and concentrates instead on using stockpiled antivirals until a strain-specific vaccine can be created.
Scientific Committee's recommendations on human influenza H5N1 pre-pandemic and pandemic vaccines
18 December 2012
A spokesman for the Department of Health (DH) announced today (December 18) that the Scientific Committee on Emerging and Zoonotic Diseases (SC) under the Centre for Health Protection (CHP) of the DH has provided its recommendations on human influenza H5N1 pre-pandemic and pandemic vaccines.
The spokesman said that after reviewing the latest scientific data, including local disease epidemiology, international experience and the World Health Organization (WHO)'s recommendations, the SC recommends providing human influenza H5N1 pre-pandemic vaccine for the protection of specific laboratory workers at higher risk of exposure to avian influenza H5N1 virus during the inter-pandemic phase.
The laboratory workers who are eligible for the vaccination are those involved in:
- large-scale production or manipulation of highly pathogenic avian influenza (HPAI) H5N1 virus;
- working with the virus over a long period;
- working with HPAI H5N1 virus strains that are resistant to licensed antiviral compounds;
- or working with strains with the potential for increased transmissibility in mammalian species.
"As recommended by the SC, a locally registered human influenza H5N1 pre-pandemic vaccine, which is based on the currently more widely circulating strain and demonstrated cross-reactivity to more clades should be the choice of vaccines," said the spokesman, adding that the DH will proceed with the necessary procedures in procuring the vaccines recommended by the SC.
The spokesman explained that a human influenza H5N1 pre-pandemic vaccine contains antigens that correspond to circulating avian influenza H5N1 virus strains that are thought to have the potential to cause a pandemic.
However, given the uncertainties about the timing and the strain/subtype of the next pandemic, physical stockpiling of additional human influenza H5N1 pre-pandemic vaccine was not recommended by the SC.
As regards pandemic vaccines, the spokesman explained that it is a vaccine against a future pandemic influenza strain with unknown antigenic composition. It will protect against the pandemic influenza strain but will only be available after the emerging virus of the next influenza pandemic has been characterised.
In view of the doubtful benefit based on currently available information, the SC at present does not recommend the option of procuring the pandemic vaccines by advance purchase agreement (APA), that is, a contract with vaccine manufacturers for reserving a certain percentage of vaccine output capacity.
The spokesman stressed, "As part of the preparedness plan for influenza pandemic, the DH has stockpiled sufficient antiviral agents for the treatment of patients as well as chemoprophylaxis for certain target groups including health care workers.
"The DH will continue to monitor the development of pre-pandemic/pandemic vaccines and APA closely and recommendations are subject to review by the SC if new evidence/option becomes available," he added.
The full version of SC's recommendations on human influenza H5N1 pre-pandemic and pandemic vaccine has been uploaded to the CHP website (www.chp.gov.hk) today.
Ends/Tuesday, December 18, 2012
Five or six years ago a number of countries elected to stockpile quantities of an experimental H5N1 vaccine, which typically only have a shelf life of 2 to 3 years, only to see them expire unused.
In a few cases, authorities opted to release some of these vaccines to high risk individuals, and even the general public, rather than see them go to waste.
In September of 2008, roughly 6,000 medical workers in Japan received an experimental pre-pandemic bird flu vaccine as a test for a larger distribution of their stockpile (see Japan: Pre-Pandemic Vaccination Priority List).
And in September of 2010 Taiwan offered a limited number of H5N1 vaccinations to the public (see Taiwan Offers Public Bird Flu Vaccinations).
While it is unknown how effective these early vaccines would be against any newly emerging H5N1 strain, many researchers believe even a fair match would help prime the recipient’s immune system, so that a single booster (instead of two shots) might offer protection (see The Prime Of Our Lives).
The logistics of producing and delivering an emergency pandemic vaccine (likely requiring 2 doses, 28 days apart) to a significant portion of the world’s population remain daunting, and with today’s technology only limited quantities of vaccine would become available after 5 or 6 months.
Ultimately the solution may lie in the development of a universal flu vaccine, one that targets a conserved epitope common across a wide range of flu viruses, that would convey protection against many strains.
Unfortunately, while progress is being made on that front, such a development is still likely years away.
