By Jamie Hansen and Ranu S. Dhillon
The H5N1 bird flu has been making news for driving up the price of eggs nationwide, but it also has the potential to spur a major epidemic if its circulation among poultry, cattle and humans is not carefully checked.
Such an outcome can be averted by taking the correct preventive steps now, said Abraar Karan, MD, a postdoctoral scholar of infectious diseases at Stanford Medicine who specializes in emerging diseases.
Karan and several colleagues recently authored a commentary in Nature recommending measures to prevent the virus from evolving and adapting in ways that would make it more deadly and transmissible in humans, potentially resulting in a pandemic. Key recommendations include:
- Protecting farmworkers by improving their access to personal protective equipment that isn't too uncomfortable to wear under the conditions they work in.
- Reducing the virus's circulation in dairy cows through consistent testing of milk samples and isolation of cattle when the virus is detected.
- Improving genomic and human surveillance to more quickly identify outbreaks and evolutions in the virus that could present a greater risk to humans.
- Preparing U.S. health systems to respond by developing rapid, decentralized testing tools, while equipping schools and other facilities with high-filtration masks, clear disinfection protocols and inexpensive air filtration systems
- Repairing public trust damaged after COVID-19 through proactive, transparent communication and efforts to "prebunk" disinformation.
Karan discussed why it is critical to act now to protect the health of humans and animals. This interview has been edited for length and clarity.
What is the case for the U.S. making significant investments to protect against this virus, given its current low risk assessment by the Centers for Disease Control and Prevention?
It is true that the H5N1 virus is not transmitting efficiently between people and that most of the 70 reported U.S. cases in humans have been mild, causing mainly conjunctivitis, or pinkeye, with only one reported death. However, flu viruses can adapt very quickly. So as H5N1 circulates between cows, chickens and humans, it can mutate or mix with seasonal flu strains to become both more infectious and more severe in humans.
Something that is not an epidemic today but could become an epidemic tomorrow is high risk.
I think of this analogy: If you drive every day, but you don't wear your seatbelt, and you don't have an accident, that's great. But the moment you get into an accident, you could be dead. So you wear your seatbelt to minimize that potential risk. It's the same thing here. Just because we don't have a bird flu epidemic today doesn't mean it's not possible to have one tomorrow -- meaning now is the time to "put on our seatbelts" by taking measures that minimize our risk.
At this point in the evolution of the virus, what is most important to watch?
Our main concerns involve the virus becoming more infectious between humans -- and more severe. This can happen as the virus circulates back and forth between humans and livestock, especially other mammals.
Influenza viruses are segmented RNA viruses, which means their genome is divided into multiple pieces that can undergo genomic changes very quickly. This is particularly likely to happen during flu season, when people and some animals, such as pigs or cows, can become infected with H5N1 and seasonal flu at the same time. When this happens, the viruses can swap gene segments in a single event to create a reassorted virus that is more virulent and/or more deadly, and therefore capable of causing a pandemic. This is what we saw in 2009 with H1N1, which caused many deaths, including in younger people.
This is the hypothetical scenario on the minds of many of us working in infectious disease. Expanding genomic and human surveillance through regular testing of milk samples on dairy farms can help inform us of how the virus is mutating -- and allow us to respond quickly if we see that it is evolving to be more infectious or severe in humans.
What is the status of vaccine development for both animals and humans and what role can vaccines play in preventing an epidemic?
We're not likely to eradicate bird flu transmission across animal species through vaccines because of the circulation in wild birds and the inability to effectively immunize all potential intermediate species.
Even for humans, the vaccines we have stockpiled for older strains of the virus have not been all that effective. RNA viruses mutate quickly, which creates a risk that any vaccines could be outdated by the time it is ready to be deployed. However, immunizing with the goal of preventing severe disease and death is reasonable and achievable. The drug company Moderna recently received a nearly $600 million award to test an experimental bird flu vaccine, but the new presidential administration is re-evaluating the funding.
Among the recommendations you make in your recent publication, which do you consider the most important or timely?
Now that the horse is out of the barn, in terms of transmission among poultry and dairy cattle, the key is preventing spillover from animals to humans. This is particularly important for people who have contact with livestock, from dairy and poultry farms to backyard chicken flocks.
A key component will be to develop a strong personal protective equipment (PPE) program -- one of the most practical and doable steps we can take. This seems simple, but it's actually very difficult -- especially in a farm setting, where protocols and trainings are not as strict as in labs, and where the nature of the work results in lots of breaks in usage.
We saw this in Colorado, when the conditions were very hot and some people removed their respirators, which resulted in them becoming infected directly from poultry.
But even if we can't make it perfect, minimizing spillovers from livestock to humans is important.
Source : stanford.edu