The current strain of highly pathogenic avian influenza, commonly referred to as bird flu, has change into a world problem. This virus has affected many tens of millions birds, some others animal speciesand a small number of individuals.
Last week the Australian government issued a warning for residents traveling to Europe, North America, South America and Asia about the risk of bird flu.
Alert posted on Smartraveller websiteprovides advice on ensuring your flu vaccine is up thus far. If you are planning to travel, this often means you have had a flu vaccine this 12 months, although whether it is 3-6 months since your vaccination you should discuss this together with your doctor.
But the seasonal flu vaccine we get yearly doesn’t actually prevent bird flu in humans. So why is it really useful in this context?
Some facts about bird flu
Smartraveller’s Notes several strains Bird flu viruses are currently circulating.
The most annoying strain, called clade 2.3.4.4bemerged several years ago from the influenza A (H5 or A/H5) strain that had been circulating for several many years.
Clade 2.3.4.4b primarily affects birds, including wild birds and poultry. It has had devastating effects on bird populations, in addition to on farmers and others involved in the poultry industry.
In recent years, clade 2.3.4.4b has adapted to infect some mammalsUnfortunately, it seems to cause serious illness in some animalsSome marine mammals have been particularly hard hit, causing mass mortality events reported in elephant seals and sea lions. Bird flu has also spread to the United States amongst dairy cows.
Compared to the huge variety of cases in animals, a comparatively small number have been reported. people infected with bird fluSince 2003, 878 cases Human cases of A/H5N1 influenza have been reported, with a small percentage reported after 2020, when clade 2.3.4.4b first appeared. Reported cases have been in individuals who had close contact with infected animals. The disease does not appear to spread from individual to individual.
In reference to the risk for travelers is lowThere are situations where the risk could also be greater, reminiscent of for people visiting livestock markets or people travelling specifically to work with wildlife or in food production.
Infections in humans H5 flu can vary greatly in severity, from mild conjunctivitis to deadly pneumonia. H5 flu strains look like sensitive to antiviral drugs (oseltamivir, also referred to as Tamiflu) and so they are generally recommended as a treatment for infections in humans, but that is not clear whether or not they reduce the risk of death in individuals with severe disease.
To date, one case of A/H5 influenza (not 2.3.4.4b) has been reported. reported in Australiain a baby who has recently returned from abroad.
One sec clade 2.3.4.4b detected on all continents except Australiaother strains of bird flu (A/H7) were reported here earlier this 12 months.
Snowboy/Shutterstock
Seasonal flu vaccines are not effective against bird flu
Seasonal flu refers to the strains of flu that flow into every year. Since the COVID-19 pandemic, three different strains have circulated in various proportions – Influenza A H1N1 (originating from 2009 swine flu strain), influenza A H3N2 (which has in circulation since 1968) and a strain of influenza B. Interestingly, the second strain of influenza B (Yamagata lineage) it seems to have disappeared during the COVID pandemic.
Seasonal flu vaccines contain the current variants of those types (A/H1N1, A/H3N2, and B), that are really useful annually by the World Health Organization. These are moderately effectivereducing the risk of hospitalization by roughly 40–60%.
Flu vaccines are quite specific in the protection they supply. In the case of seasonal vaccines, even very small changes that occur in the virus from 12 months to 12 months are enough to permit it to “escape” vaccine-induced immunity. That is why seasonal flu vaccines they do not provide any protection against influenza A/H5.
Preventing the emergence of a bird-human hybrid strain
The rationale for recommending influenza vaccination for travellers in the context of the current avian influenza epidemic is that seasonal influenza vaccines may help reduce the risk of co-infection with an A/H5 strain and a seasonal influenza strain.
When this happens, there may be a likelihood that the genetic code of the two strains of the virus will “recombine.” This could have the ability to hold a seasonal human virus with the severity of a bird flu virus. The 2009 swine flu strain arose from recombination Over the years, several strains have change into more contagious to humans.
Of course, a more practical vaccine would come with an H5 strain to generate immune responses specific to the H5 influenza strain. Vaccine manufacturers have H5 vaccines have been developed for years, but up to now only Finland implemented the H5 vaccine amongst a small group of people that work closely with potentially infected animals.
Currently risk level The risk that H5 poses to humans is not considered to be sufficient to require a particular vaccination programme because the potential advantages are small in comparison with the costs and potential risks of any recent vaccination programme.
The Value of the Flu Vaccine for Travelers
Seasonal flu vaccines protect against flu infection and may reduce the risk of simultaneous infection with human and bird flu strains. Bird flu aside, for most travelers who haven’t received a flu shot this 12 months, reducing the risk of their travel plans being disrupted by the disease must be reason enough to get vaccinated.
For individuals who have already received a flu vaccine this season, as with COVID vaccines, protection appears to be greater after vaccination fade over timeSo if you’re travelling to the Northern Hemisphere during the winter months and it’s been greater than 3 to six months since your last flu shot, your doctor may recommend you get one other one.
Bird flu poses a low risk to most travellers, but people should take sensible precautions, reminiscent of avoiding close contact with birds at markets.
