Key takeaways:
~ Some people are more susceptible to different flu strains than others.
~ Check your genetic variants below to see which flu strains you are likely to be more or less susceptible to.
~ The Lifehacks section gives you the well-researched, natural options for fighting the flu — things that you may want to have on hand during flu season.
Members will see their genotype report below, plus additional solutions in the Lifehacks section. Consider joining today.
Flu season, genes, and solutions:
The flu – influenza – is a respiratory disease caused by two virus types, influenza A and influenza B.
The flu goes around each year — usually in November/December and then again in Feb/March in the Northern Hemisphere. Even with the flu vaccine available, about 10 to 40 million people in the US get the flu each year.[ref] The WHO estimates that about 1 billion people get the flu each year, with about 3-5 million having more severe illness and 300,000–500,000 deaths (2017 numbers).[ref]
The efficacy of the flu vaccine depends on which strain ends up circulating for the year. For 2024 in the US, the CDC estimates that the flu vaccine will be about 35% effective in preventing hospitalization and severe illness.[ref]
Flu symptoms include:
- Fever, chills
- Fatigue
- Body ache
- Cough
- Sore throat
- Stuffy nose
- Headache
In some cases, influenza can cause viral pneumonia or result in someone getting a secondary bacterial in the lower respiratory tract which causes pneumonia. In addition, an influenza virus infection can also lead to complications affecting the heart, central nervous system, and other organ systems.[ref]
Influenza viruses:
Four types of flu viruses have been identified: Influenza A, B, C, and D.
Influenza is a negative-strand RNA virus in the family Orthomyxoviridae. Within each type, multiple strains are going around each year.[ref][ref] The exact flu strain changes each year by recombining parts of different strains.
- Influenza A (H1N1 or H3N2): Sometimes called swine flu, this variant usually arises from recombining H1N1 strains from birds, pigs, and humans.[ref] H5N1, the new bird flu, is a type of influenza A.
- Influenza B: About 20-30% of flu infections each year are influenza B strains.[ref] Influenza B is usually found only in humans.
- Influenza C: Usually causes mild respiratory illness or is asymptomatic. Most people have antibodies to influenza C by the time they are teens.[ref] Influenza C is usually found only in humans.
- Influenza D: Mainly circulates in cattle and pigs.[ref]
So far this year (fall/winter 2024), the CDC reports a mix of influenza A(H1N1) and influenza B(H3N2).[ref]
Interestingly, several studies show that most people exposed to a new flu strain don’t get the flu, or at least don’t get any symptoms. A study on the swine flu pandemic (2009) noted the “majority of people newly exposed to one of the most dangerous viruses to circulate in human populations in recent history… did not notice any symptoms.”[ref]
We have robust immune systems which fight off viruses in multiple ways. Plus, we all have slight genetic differences in immune system genes, giving some an advantage for certain flu strains.
Differences in immune system genes are a feature allowing parts of a population to survive new pathogens.
Cell entry and replication:
With Covid in the news for the past few years, we have all gotten a crash course in SARS-CoV-2 virology and how the virus enters the cell via the ACE2 receptor.
The flu virus is not as picky about needing a specific type of cell receptor for entry.
Hemagglutinin is a cell surface protein on the influenza virus that helps it to attach to the host cell. It attaches to glycans, called sialic acid, on the surface of cells in the respiratory tract.[ref] Sialic acids cause a negative charge on cell surfaces and help keep water at the cell’s surface. Thus, they are found in areas with a mucous membrane – such as the nose, lungs, and intestines. And this is where the flu virus easily enters the cell by endocytosis and replicates.
Inside the cell, the flu virus makes its way to the cell nucleus, where it uses the host’s RNA replication enzymes to transcribe the viral proteins for replication.[ref]
All influenza viruses are enveloped, negative-sense single-strand RNA viruses. Influenza A and influenza B viruses contain haemagglutinin (HA) for attaching and entering the cell and neuraminidase (NA), which is used for viral release from the cell once it has replicated. The RNA is segmented, which means that the different strains of flu viruses can easily swap segments to become a new strain.
Detecting and fighting the virus:
The influenza A viruses are detected by toll-like receptors 3, 7, and 8 (TLR3, TLR7, and TLR8), as well as RIG-I. These receptors then activate antiviral inflammatory responses. An excessive response can lead to a hyperinflammatory state, but not enough response can let the virus replicate for a longer period of time. Thus, a balanced immune response is needed to fight off the flu, without the immune system going overboard and causing damage to the body.[ref]
Transmission of the flu:
The flu is an airborne virus, spreading via aerosols and probably by direct contact.[ref]
Airborne transmission is defined as inhaling infectious viruses smaller than 5 μm at distances greater than 3-6 feet from the infected individual. Influenza, RSV, rhinovirus, SARS-CoV, MERS, and Covid are all spread this way. Viral aerosol particles can linger in the air for hours to days.[ref]
Understanding airborne viruses can help explain how the flu is transmitted between people and why it is seasonal…
Why is the flu seasonal?
The question of why the flu always goes around about the same time in a region has puzzled researchers for years. There are theories on vitamin D levels, UV light changes, seasonal movement, and humidity changes.
For humidity, the theory is that lower humidity allows the flu aerosol particle size to become smaller and remain in the air longer. Viruses have specific humidity ranges where they are likely to linger in the air and be breathed in by people.
But seasonal relative humidity changes don’t tell the whole story. What feels like a humid day in Grand Junction, CO, would be considered a very dry day in Charleston, SC.
A recent study points towards the combination of humidity changes along with changes to the mucus membranes of people living in the area.
Take Florida, for example. For people whose noses and mucus membranes were used to more humidity, a drop in humidity will feel dry, and there will be changes to the mucus production in the noses adapted to the area. Similarly, Wyoming may always have less humidity than Florida’s driest day, but a change from 15% relative humidity to 8% will dry out Wyoming noses.[ref]
Genetics is the other key to who gets the flu, so let’s dig into the genes identified in research studies.
Beating Flu Genotype Report:
Lifehacks:
You wake up with muscle aches and a fever… What are your options? The research studies are presented here so you can decide what is best for you.
Research on Natural Solutions for the Flu
Vitamin C:
A small study in healthy adults showed that 1,000 mg of vitamin C taken every hour for six hours at the onset of symptoms reduced symptoms by 85%. After the first six hours, participants took 1,000 mg three times a day.[ref]
Related article: Vitamin C genomics
Zinc:
An important co-factor in immune response pathways, zinc deficiency can increase the risk of severity in respiratory viruses, including the flu.[ref] Before flu season, be sure to get enough zinc in your diet, or consider supplementing with a low-dose zinc supplement. Dietary sources of zinc include oysters, crab, beef, elk, lamb, bison, and certain types of mushrooms. The recommended dietary allowance (RDA)for zinc is 11 mg/day for men and 8 mg/day for women
Related article: Zinc genes
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Guide: Saving Money on Supplements
Five quick examples of how you could use your genetic data to dial in the supplements worth trying and which ones to skip for now.
Vitamin D, Genes, and Your Immune System
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