The Emerging Pandemic Risk of α-H1N2 Swine Flu Virus

Since COVID-19 took the world by droplet infection, we’ve been looking for the next pandemic - mostly to avoid it. The current challenger is the α-H1N2 swine flu virus, a strain that some scientists are calling a serious pandemic threat.

Recent research published in Nature shows that it has quietly circulated among pigs and is emerging now and may spark a global health crisis.

Just like COVID-19 was not the first Coronavirus we saw, there have been swine flu outbreaks before, most notably in 2009 when the H1N1 strain was called a pandemic by the WHO.

Communications has uncovered critical insights into the α-H1N2 swine flu virus, a strain that poses a serious pandemic threat. Let's explore the fascinating and alarming findings of this groundbreaking study.

But first, here is a small capsule of some crucial headlines in the HealthTech world.

In the Spotlight

1. Germany’s Merck Group shares drop 10% after scrapping trial of promising cancer drug
2. Why cancer risk declines sharply in old age
3. U.S. Government to Pay Moderna $176 Million to Develop mRNA Flu Vaccine
4. FDA approves donanemab, Eli Lilly’s treatment for early Alzheimer’s disease
5. Data breach at Geisinger may have exposed data from 1.2M patients

Potential Pandemic Risk from α-H1N2 Swine Flu Virus

A recent study has highlighted the pandemic potential of the α-H1N2 influenza virus, which is circulating among swine. Influenza A viruses (IAVs) in swine possess high genetic diversity and can transmit to humans, often leading to mild illnesses. However, the lack of population-level immunity to these viruses raises significant concerns about their ability to cause widespread outbreaks

Evolution of Flu

The flu is known for its ability to constantly evolve - the viral proteins (the H# and N# in the flu strain name) relate to which type of proteins they have. It evolves in two distinct patterns - one of the constant minor evolution that requires us to get a new flu shot every year (antigenic drift), and one in the way that it can suddenly have a big evolution and cause a worldwide pandemic like the Spanish Flu (antigenic shift).

The analogy I use for antigenic drift is like updates to your computer’s Operating System - if you use Windows, it occasionally runs Windows updates and minor improvements are made, but you won’t notice much difference. A menu might move, and settings rearranged, but you can recognize and deal with it because it's still similar to what you know despite some software changes. It slowly changes over time with each update, allowing you to still recognize the majority of the features. This is how your body recognizes antigenic drift - it has just slightly changed and your immune system is like “Wait a minute.. I remember you!!” and will react accordingly. (especially with the annual flu vaccine which has 3-4 strains that are predicted by the CDC to be prevalent that year).

Antigenic Shift is a sudden and major shift in the proteins that is unrecognizable to the body. This is like going from Windows 10 to 11. It’s a whole new program, a different layout, that annoying search bar, and some random AI feature crammed in. So it's almost like a brand new infection, not just a variation of a known infection - these are the ones that cause pandemics.

So the viral proteins, neuraminidase (NA) and hemagglutinin (HA) can undergo seasonal Antigenic Drift, affecting virus transmissibility, infectivity, and host specificity, and occasionally Antigenic Shift which causes these pandemics.

Study Overview

The study developed a decision tree to characterize and assess the pandemic risk of swine IAVs.

Researchers focused on two specific strains:

• α-H1 (1A.1.1.3) clade strain A/swine/Texas/A02245420/2020 (α-swH1N2).
• γ-H1 (1A.3.3.3) clade strain A/swine/Minnesota/A02245409/2020 (γ-swH1N1).

These strains were selected based on their geographic distribution, detection frequency, interspecies transmission potential, and lack of cross-reactivity with human seasonal vaccines.

Findings

• Antigenic Differences: Previous research indicated that α-swH1N2 strains have significant antigenic differences from human vaccine strains, leading to lower recognition by human immune sera.
• Airborne Transmission: Ferrets, used as a model for human infection, showed that α-swH1N2 could be efficiently transmitted via airborne routes, even among those with prior immunity to other influenza strains. However, prior immunity did reduce the severity of the disease.
• Undetected Spread: Ferrets with pre-existing H1N1pdm09 immunity shed less virus and showed reduced disease severity, but they could still transmit the α-swH1N2 virus, posing a potential risk for undetected spread.
• CD8+ T-Cell Response: In the absence of neutralizing antibodies, CD8+ T-cells can confer protection against emerging influenza virus strains by recognizing conserved internal proteins. This cross-reactivity was shown to aid in rapid recovery and efficient virus clearance, even in cases where ferrets had no prior immunity to α-swH1N2.

Implications and Recommendations

The study's findings underscore the higher pandemic potential of the α-swH1N2 strain compared to the γ-swH1N1 strain. This necessitates enhanced surveillance efforts to monitor and detect zoonotic events involving swine IAVs. Additionally, expanding vaccination campaigns for swine can help reduce viral circulation in source populations, potentially mitigating the risk of a future pandemic.

Our Expert Take

Everyone’s gunning for the next pandemic - COVID-19 definitely woke the world up to the potential of viral evolution. Though many “threats” have come and gone, it is a good change that the mention of viruses and threats attracts eyeballs.

The thing we don’t want is Viral alert fatigue - many such warnings have come and gone since COVID-19, and soon the public will just ignore them. The perfect storm of transmissibility, infectivity, and lower mortality rates is what the biggest concern is. Something that is “too deadly” like the Ebola Virus, actually kills its hosts too fast for it to become a pandemic. That is also why these strains that appear (if you remember Delta from Covid) - the dominant ones are always LESS DEADLY because that allows a longer time for the virus to jump to a new host.

Overall, continue with vaccination and cautious optimism, but it is worth keeping an eye on this as it is something that we have seen before, though the scale of the 2009 swine flu pandemic has been dwarfed by COVID-19.

That's a wrap on this edition.

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