Vaccines and antiviral drugs

Is there a vaccine effective against HPAI H5N1 in humans?

A number of H5N1 vaccines are currently in various stages of development and early results are encouraging.  Vaccine manufacturers are working on different types of vaccine, using H5N1 viruses isolated from different locations.  Mass production of an H5N1 vaccine will not take place unless it mutates into a pandemic strain.

The Department of Health secured a limited amount of HPAI H5N1 vaccine for the UK. This will be used for research and for priority groups such as healthcare workers, should the pandemic occur in the near future.

Will normal seasonal influenza vaccine protect me against avian influenza?

The normal seasonal influenza vaccine provides protection against currently circulating strains of human influenza. It does not provide protection against HPAI H5N1. For information about who should receive seasonal flu vaccine please see the Department of Health flu page.

Are presently available vaccines useful in averting an influenza pandemic?

Not really, except when used in a very precisely targeted way. The current seasonal flu vaccine protects against circulating human strains. Vaccination with seasonal flu vaccine reduces the risk that humans at higher risk of exposure to an avian flu virus (eg groups such as poultry workers) might become infected with both human and avian viruses at the same time. Such dual infections give the avian and human viruses an opportunity to exchange genes, possibly resulting in a new influenza virus subtype with pandemic potential.

Flu vaccines are produced on an annual basis for routine use in protecting humans during seasonal epidemics of influenza. They offer no protection against infection with the HPAI H5N1 virus.
For these reasons, WHO has issued guidelines for the vaccination of groups considered at high risk of expose, with the current trivalent influenza vaccine, in countries experiencing outbreaks of HPAI H5N1 in poultry.

Is it true that some countries are starting to stockpile an HPAI H5N1 vaccine? What is the UK doing?

Until the pandemic starts, it is difficult to predict what strain of influenza will cause it. Predictions may prove to be wrong or the predicted virus may have changed enough for a pre-prepared vaccine to be ineffective.

In the event of an influenza pandemic, an appropriate vaccine will be developed and made available. This could take up to six months from identifying the strain of influenza responsible for the pandemic. The UK has secured advanced supply contracts with pharmaceutical company GSK and Baxter Healthcare to supply a pandemic influenza vaccine as soon as the pandemic strain is identified and made available by the World Health Organization for the entire UK population.  The contracts are worth £155.4 million over four years, and are part of the Government's continued work to prepare for and reduce the impact of a possible flu pandemic.

The European Centre for Disease Prevention and Control has considered a number of questions around human H5N1 vaccines.  A report is available on their website.

Are any drugs available for prevention (prophylaxis) and treatment?

Yes. Two classes of drugs are available (the M2 inhibitors - amantadine and rimantadine - and the neuraminidase inhibitors - oseltamivir and zanimivir). However, initial analysis of viruses isolated from the recently fatal cases in Viet Nam indicates that the viruses are invariably resistant to the M2 inhibitors. Oseltamivir has been demonstrated to be effective against the current HPAI H5N1 strains under laboratory conditions. Most experts agree that neuraminidase inhibitors will be vitally important in managing the consequences of a future influenza pandemic. The UK government has currently acquired a stockpile of antivirals, sufficient for 25% of the population.

Should I obtains some Tamiflu® to protect me from avian flu?

If avian flu was identified in the UK, the risk would almost entirely be confined to those who have close contact with infected domestic poultry or infected materials from poultry. This would include poultry farm workers, veterinarians and others involved in disease control. If outbreaks occurred in the UK the HPA would work with these groups to offer protection such as antivirals to those exposed. The European Centre for Disease Prevention and Control ( ECDC) has not changed its risk assessment. The risk assessment remains that the direct risk to the health of people in Europe is very low, but not zero.

In the UK oseltamivir (trade name Tamiflu®) or other appropriate antiviral agents would be used for the prevention of avian flu in people exposed to the virus or to protect people, including poultry workers, who might become exposed to the virus during disease control activities. Such people will be supplied with appropriate antiviral drugs, under prescription, as soon as possible after potential exposure and within at least 48 hours of exposure.

It is not recommended that people should stockpile Tamiflu® personally as it will encourage inappropriate use of medication.

Should I ask my GP to prescribe influenza antiviral drugs if I am going to an area where avian influenza outbreaks are occurring?

To date, there have been no cases of confirmed HPAI H5N1 infection in UK travellers returning from these regions. Transmission of avian influenza to those visiting a country affected by highly pathogenic avian influenza (HPAI) is highly unlikely if you abide by the travel advice posted on the Department of Health and NaTHNaC websites.
At present, it is not recommended that persons travelling to countries affected by avian influenza carry antiviral drugs, unless they will be placing themselves at special risk (eg going to work in a laboratory which handles HPAI H5N1 viruses).

Last reviewed: 13 August 2008