What is the H5N1 virus (avian influenza or “bird flu”) and should you and your loved ones be worried about your health? With all the information circulating online and in the media, it’s hard to tell fact from fiction. To help you understand how to prevent the infection—and at the same time dispel some myths—our infectious disease expert, Dr. Caroline Quach [1], will answer some of your most pressing questions about this headline-grabbing strain of the flu virus.
At the moment, avian influenza is spread only through direct contact with infected poultry.
No. The virus is spread through contact with live poultry, most often on farms or in slaughterhouses.
Our biggest concern is that a person will be infected with avian influenza and human influenza at the same time. We know that influenza viruses have a strong ability to combine with other types of flu viruses. For human-to-human contact to become possible, all it would take is for the avian influenza virus to combine with a human influenza virus and take on the latter’s ability to spread between humans.
The H1N1 influenza virus that caused the last pandemic is different from the avian influenza virus (H5N1). The vaccines currently available do not protect against H5N1. However, clinical trials are underway to develop new vaccines.
Children under age 5 are at higher risk of catching any respiratory virus—such are the joys of school and daycare. However, in this situation, because the main risk factor is contact with live, infected poultry, children under 5 are largely unaffected. A few cases in children have been reported in Asia, all of which can be linked to contact with poultry, and these cases have been associated with serious illness.
At the moment, the mortality rate is around 59%, meaning that 59 out of every 100 people infected with the virus will die from it. However, the cases tested and reported to the public health authorities are obviously the most severe, which could be contributing to an over‑evaluation of the mortality rate.
In order for strains of human influenza and avian influenza to combine, both viruses must be present in the same host at the same time—with a little bad luck thrown in! The more contact between the two viruses (greater number of co-infected individuals), the higher the statistical risk of recombination. Hence the importance of getting the seasonal flu vaccine to prevent both viruses from being present in the same person at the same time. This fact has been taken into consideration in formulating the vaccination recommendations for workers in contact with chicken, especially those working in slaughterhouses.
A vaccine is currently being developed (phase 3) by a Québec company and has been administered to several volunteers to date. In the event of a pandemic, a potential vaccine is almost ready.
As for antiviral medications, the virus still seems to be sensitive to the medications currently available on the market (oseltamivir and zanamivir).
Public health authorities, jointly with the WHO, have been preparing for this scenario for a long time now. Pandemic preparedness plans are in place that should halt the spread of the virus. However, the most important thing will be to remain on high alert for the first signs of any changes in way the virus spreads.
In Québec, flu vaccination recommendations have been issued to reduce the risk of complications in people at risk of severe flu symptoms. As such, the flu vaccine is offered free of charge to babies between the ages of 6 and 23 months, to children and adults with chronic medical conditions (e.g. diabetes, asthma), and to people with weakened immune systems. People age 60 and over and anyone in contact with an at-risk person are also being vaccinated. Of course, everyone else is welcome to be vaccinated, however, they would have to pay for the vaccine at a clinic.
You’re right, 59% is very high, which is why we’re worried about avian influenza combining with a strain of human flu. What I said earlier still stands, however: if we test and report only the most serious cases, then the mortality rate for all severity levels combined may be lower than in actual fact. In any case, this avian influenza should not be taken lightly.
A diagnostic lab test is only way to tell the difference between the avian flu and a regular flu. However, we will not do a lab test unless you’ve been in contact with poultry in one of the affected countries. From a clinical standpoint, it is impossible to distinguish the avian flu from a bad case of the seasonal flu, and it can sometimes even be difficult to tell it apart from a respiratory infection (cold) caused by another virus.
Of course, an isolated case is precisely that: isolated. The flu season in Canada seems to be running its normal course. Are the media blowing things out of proportion? You’d have to ask them, since they have a duty to provide information. As for public health authorities, they have a duty to prevent disease and, as such, an obligation to inform the public about any potential problem situations. The public health authorities keep members of the health network informed so that we know what to look out for. In my opinion, public health authorities have been more reassuring than alarmist lately.
People travelling to China, as with any destination, should visit a travel medicine clinic for the appropriate vaccines. After that, it all depends on where you go. Regular hand-washing is probably the most important thing to remember. You should also avoid poultry markets, where large numbers of birds are found together in one place.
If only there were a simple answer to that question... and if you actually had that answer, I’d be out of a job! That being said, my approach is to state the facts on the safety of vaccines, but also to be frank about the perceived risk of vaccination versus the real risk of a serious disease that could otherwise have been prevented. The most serious cases can be very heartbreaking. Imagine looking a parent in the eye who asks you, “Doctor, could I have done something differently?” and knowing that, yes, the disease could have been prevented by a simple vaccine. And also knowing that the diseases for which vaccines have been developed are highly arbitrary: it’s impossible to know in advance who will contract them and who will develop serious complications. What’s more, there are still no approved treatments for many of these diseases (for example, measles). So, that’s a very tough question, indeed.
It’s important to remember that H1N1 is not the same thing as H5N1 (avian). Someone who had the H1N1 flu during the 2009 pandemic should still be protected against this year’s strain of the H1N1 virus, since it doesn’t seem to have changed much in the past few years. After 2009, the H1N1 flu became considered a seasonal flu; as such, it has been included in all flu vaccines since 2009.
I don’t have any data on deaths due to the H1N1 virus, specifically in people who had been vaccinated. We know that the seasonal flu vaccine has an efficacy rate of around 60-70%, depending on the year and the patient population. We also know that some patients who get vaccinated still get the flu, especially if they’re older (phenomenon of immunosenescence) or if they have a weakened immune system. Some people even need to be hospitalized. Personally, I’ve never seen a death from the H1N1 flu in a person who had been vaccinated, but that doesn’t mean it can’t happen.
We recommend vaccinating children starting at the age of 6 months; the flu vaccine is still available at the various clinics (CLSCs). As to whether it’s better to keep your baby at home, that’s fine as long as no one (and especially no one with symptoms) comes to visit. The problem is that the flu can spread even before symptoms appear, and isolating yourself may not be the most appealing solution (it’s certainly not one I would enjoy).
The cytokine storm that you’re talking about can occur as a result of the vaccine, but can also be triggered by the flu in people with an overly robust inflammatory system. Currently, there is no indication that the vaccine causes excessive inflammation. As for whether vitamin D and other anti-inflammatory agents can have a beneficial effect in someone with the flu, so far no studies have been done on the subject, although that’s a very interesting question. A recent study showed that women are more likely than men to have a strong immune and inflammatory response to the flu vaccine, and that the higher a man’s testosterone level, the less he will react to the vaccine (fewer antibodies produced). It’s all a mystery!
Links
[1] https://www.thechildren.com/departments-and-staff/staff/caroline-quach-md-msc-frcpc-pediatric-infectious-diseases-and-medical
[2] https://childrenfoundation.com/donate-now/
[3] https://www.thechildren.com/departments-and-staff/departments/department-of-infectious-diseases