Tag Archive for: flu

Flu Shots and Alzheimer’s Disease

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One of the benefits of large cross-sectional studies, especially in the age of electronic medical records, is that medical tests and treatments can be examined while examining diagnoses at the same time. The Veterans Health Administration is one of many medical databases that can identify relationships between health factors and the onset of disease.

In a recent study, researchers used a large medical records database called Optum Clinformatics Data Mart. The methodology section was long, but essentially they divided potential subjects into those who did not get a flu vaccination at all and those who got at least one flu vaccination every year or more. They identified their potential subject list and then tracked them for four years to see if they received a diagnosis of Alzheimer’s disease (AD). In case you were wondering, people under 65 were excluded because AD does not manifest itself appreciably until after that age.

The results were more than a little interesting. Those who got at least one flu shot had a 40% reduced risk of getting diagnosed with AD. Before you even think, as I would have, “How many subjects were there?”–there were close to a million subjects in each group. The better question is how would a vaccination reduce the risk of getting AD? We’ll examine that question on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: J Alz Dis. 88 (2022). 1061–1074. DOI 10.3233/JAD-220361

Another Path to Trained Innate Immunity

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There is one more action that may give a person a way to enhance trained innate immunity short of catching COVID-19 itself, and that’s to catch a cold. Specifically, a coronavirus cold. I read a great article in the New Scientist that I’ll summarize for you. I urge those of you who want to know more to read the paper listed below.

There are four fairly common coronavirus colds we all get at some time: OC43, HKU1, 229E, and NL63. In a study cited by the article in the New Scientist, researchers collected data from medical records of just under 16,000 patients. Of those, 875 had a documented case of coronavirus colds verified by a test; the rest of the subjects did not. Those who had a confirmed case of one of the types of coronavirus colds had milder cases of COVID-19, fewer required intensive care, and fewer had to be put on mechanical ventilation. The mortality rate was 4.8% in those who had a prior cold and 17.7% without a verified cold test.

The upside is that it seems to provide some trained immunity against COVID-19. The downside is that the immunity seems to wane over the years. I think this research is important because it shows one more way to train the immune system. It may not be practical in the real world, but if you happened to catch a simple cold in the past six months, you may have some innate immunity—if you happened to catch the correct form of the cold virus. For the rest of us, the flu shot is still the best course of action in training our immune system.

What are you prepared to do today?

        Dr. Chet

References:
1. The New Scientist. https://bit.ly/35yxbDY
2. J Clin Invest. 2020. https://doi.org/10.1172/JCI143380.

How to Train Your Immune System

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Here’s where we stand: healthcare workers in the Netherlands who got last year’s flu vaccine had fewer cases of COVID-19 than their unvaccinated counterparts. In addition, white blood cells treated with the flu vaccine, with or without the tuberculosis vaccine, demonstrated enhanced immune responses when exposed to the COVID-19 virus.

Where does this lead? It’s a quality known as trained innate immunity: exposure to one vaccine, such as the flu vaccine, will train the immune system to respond to another virus such as COVID-19. However one test-tube study does not prove it will work in the real world. Let’s look at some additional research.

The Flu Vaccine and COVID-19

Several retrospective studies have looked at the flu vaccine and COVID-19. In two studies from Italy, people over 65 who got the flu vaccination had a lower mortality rate from COVID-19. There are several more observational studies, but these studies don’t prove cause and effect.

There are problems doing clinical trials, ethical considerations being one of them; for example, if getting the flu vaccine proves to have a beneficial effect, it puts the people in the study who did not get the flu vaccination at risk. There’s also the possibility that it might have been other factors that were actually beneficial, such as lifestyle. It’s all very complicated.

Other Vaccines and COVID-19

Several studies have reported an enhanced immune response against COVID -19 after certain vaccinations. The polio- and measles-containing vaccines have been identified as stimulating the immune system and providing protection against covid-19. The bacillus Calmette-Guérin (BCG) vaccine against tuberculosis could protect against COVID-19 as well. Both have been investigated as potentially being immune-stimulating against severe upper respiratory infections. In countries where BCG is given on a regular basis, the rates of COVID-19 have remained lower than in countries that no longer use it because tuberculosis has been eradicated for the most part.

The Bottom Line

These are observational studies; there’s a lot of research to be done to find out how vaccinations for one virus can provide benefits against a completely unrelated virus. Trained immunity means immune cells are reprogrammed in some way. The “how” is important because what we may find out is that there’s another way to do it, or research may find other factors such as vitamin D status that complement the vaccinations to enhance trained immunity.

One lesson this foray into trained innate immunity has taught me is that our immune system gets weaker as we get older and must constantly be “trained.” It’s not just diet, exercise, and supplements that help our innate immunity; it seems that exposure to other viruses in the form of vaccines may help protect us against severe cases of COVID-19 and possibly other viruses as well. Right now the simplest way to do that is to get the current flu vaccination. We may not evade catching COVID-19, but having a better-trained immune system may help us avoid the most severe symptoms and possibly even death.

I got my flu vaccination and so did Paula. Talk with your physician and see if it’s right for you. Your body. Your choice. But I hope you’ll do whatever you can to put the odds in your favor.

What are you prepared to do today?

        Dr. Chet

References:
1. medRxiv preprint doi: https://doi.org/10.1101/2020.10.14.20212498
2. Nat Rev Immunol. 2020 June; 20(6): 375–388.

How Vaccines Can Affect COVID-19

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In vitro studies, more commonly called test-tube studies, are used when you want to see if there’s a relationship between cells and microorganisms. In the case of the researchers in the Netherlands, blood cells, vaccines, and the COVID-19 virus were used. While the laboratory techniques were complex, here’s what they found.

The researchers isolated peripheral blood mononuclear cells from the Buffy coat layer of cells. The Buffy contains primarily white blood cells after centrifugation. The researchers then exposed the white blood cells to the flu vaccine commonly used in the Netherlands for 24-hours. Half the samples were also exposed to the bacille Calmette-Guérin vaccine, typically used for tuberculosis. After a week, the samples were exposed to the COVID-19 virus. The objective was to see if immune system markers were increased after exposure to the virus.

The flu vaccine increased the immune capability of the white blood cells. The addition of the BCG vaccine increased the capability of the immune response. The cells were better able to make cytokines faster. If it happened in humans, the cytokines would be able to respond faster thus reducing the ability of the COVID-19 virus to replicate.

What does this all mean? I’ll finish this on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: medRxiv preprint doi: https://doi.org/10.1101/2020.10.14.20212498

The Flu Shot and COVID-19

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This week, I’m going to review a series of studies that outline a strategy that includes getting the current flu vaccination. The first study is an observational study. In my opinion, it’s the way research should begin: look for relationships between factors first, and then conduct experimental trials.

Researchers in the Netherlands used the medical records database of a large hospital to find out the answers to a couple of questions. First, of over 10,000 healthcare workers who worked there, they wanted to find out how many got the flu vaccination during the 2019–2020 flu season last fall. Then they examined how many employees got the COVID-19 infection since the pandemic began. They learned that of those who were not vaccinated, 2.23% got the COVID-19 virus; of those who got the flu vaccination, 1.33% got COVID-19. That works out to a 39% reduction in the risk of catching COVID-19 for people working in a healthcare setting if they get vaccinated for the flu.

As we know, there’s not a cause-and-effect relationship in these types of studies. But it does indicate that it’s a place to look—which is exactly what they did in the next phase of the research paper. More on Thursday.

What are you prepared to do today?

        Dr. Chet

Reference: medRxiv preprint doi: https://doi.org/10.1101/2020.10.14.20212498

Build Herd Immunity: Vaccinate

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Let’s take a look at both types of herd immunity with the goal of deciding which is better in 2017 when it comes to the flu vaccination.

Natural Herd Immunity

The benefit of natural herd immunity is the innate ability of the immune system to protect against other forms of the same virus. No question that’s a benefit that’s not available via vaccination to any degree. In response to the initial Memo on the flu vaccinations, someone posted a link on Facebook to an interesting study (1).

In that study, researchers examined the immune response of children to the flu vaccine several years ago. The results indicated that vaccinations did not promote the ability of the immune system to manufacture specific types of immune cells that would protect against variations of the viruses in that flu vaccine. It was a small study, but it demonstrates why we need flu vaccinations every year: one shot does not fit all viruses.

The downside to natural herd immunity is obvious: in order to get immunity, lots of people have to get sick. The flu can knock a healthy person out for a few days—inconvenient but not usually life threatening. But for the very young, the elderly, those who are pregnant, and those with an auto-immune disease, it can be life threatening.

The strains this year are not especially virulent, but that begs the question: what if there’s a strain that’s similar to the Spanish flu of 1918-1919? A half million people died in that pandemic. How many people would we be willing to risk to achieve natural herd immunity?

Vaccination Herd Immunity

When it comes to the flu vaccine, there are a couple of concerns besides the potential lack of protection against future viruses. The first is allergies to eggs because the vaccine is typically grown in eggs. Good news: there are some vaccines available that are made from recombinant DNA and thus do not need to be grown in eggs.

The second are the preservatives that are used to keep the vaccine safe when used in multiple doses per vaccine vial. The primary concern is thimerosal, a mercury-based preservative that has been used since the 1930s. There are thimerosal-free vaccines available if you want to avoid it altogether; the single-dose vaccination, for example. However the amount and type of mercury found in a vaccination will be eliminated by your liver’s detoxification system within 24 to 48 hours, so I wouldn’t be concerned about it.

The real benefit to vaccination herd immunity is also obvious: lots of people don’t have to get sick in order to gain the immunity to the flu viruses in this year’s flu vaccine. True, we may have to get a yearly flu vaccine, because there are always new viral flu strains. However it seems worth it.

The only issue is getting enough people to get each year’s flu vaccination. The numbers have to get to more than 80% to develop herd immunity.

The Bottom Line

I’ve always recommended that people assess their immune systems before getting a flu shot. As I said last week, I typically don’t get one because I rarely get sick. However, with a two-year-old grandson, I’m more concerned about keeping him safe. He’s very healthy, but viruses don’t discriminate. This is not about me being able to handle the flu if I get it; it’s about trying to prevent those most at risk from getting it. For me, vaccination herd immunity is the correct way to go.

What are you prepared to do today?

Dr. Chet

 

Reference: J Virology. 2011;85(22):11995–12000.

 

What’s Herd Immunity?

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Herd immunity is a way to protect a population against the transmission of an infectious disease from one person to another by increasing the number of people who are immune to the disease. This results in lower transmission of the disease and thus protects more people or “the herd”; herd immunity is the only way to protect people who can’t get the flu shot, such as the very young, the elderly, pregant women, and people with compromised immune systems.

There’s a lot written on the net about herd immunity, and most of it’s confusing or plain misleading, especially when it comes to vaccinations. I’m going to break it down to natural herd immunity and vaccination herd immunity. Today, I’ll define both terms.

Natural herd immunity develops as many people become infected, get sick, and generate antibodies to the virus or other pathogen. When a large number of people get infected and generate an immunity to the virus, those people can no longer catch that virus; thus they won’t be transmitting it, and that protects the rest of the herd. A side benefit is that it will also provide some immunity to similar viruses.

Vaccination herd immunity uses vaccines to help people become immune to a disease without getting sick. When enough people become vaccinated, the herd immunity goes into effect: those people can no longer catch that virus; thus they won’t be transmitting it, and that protects the rest of the herd.

In both cases, the issue is getting enough people to be immune to the disease. Estimates vary but the target is somewhere between 80% and 94%. The question is simple: do we want 80–94% of the population getting sick or do we want vaccinations? More on this question on Saturday.

What are you prepared to do today?

Dr. Chet

 

Further Reading:
1. http://www.pbs.org/wgbh/nova/body/herd-immunity.html
2. https://vector.childrenshospital.org/2017/03/social-media-mumps-herd-immunity/

 

What’s Viral Shedding?

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Based on the response to my email about the flu vaccination, people raised a few questions and I had one of my own. The first question is about viral shedding. Your first thought is probably “What’s that?”

Viral shedding is the period of time when you’re infected and can transmit the flu virus to someone else—it’s when you’re contagious. The question from the reader wondered whether someone who has been vaccinated will still be contagious to others if they’re infected with the flu. The answer is yes; being vaccinated against this year’s flu will not inhibit your ability to infect others if you get the flu. Remember, some people who are vaccinated will still get the flu.

The problem with the flu is that you can be shedding the virus while you still feel fine. You can be infectious up to a day before the onset of symptoms and up to 24 hours past the end of the fever. The difference may be related to the form of flu, whether influenza A or B. However, the data are not completely clear.

The point is that you should still be cautious if you begin to feel symptoms, whether vaccinated or not. While you can’t catch the flu from the vaccination because the virus used is dead, you might still get the flu. The goal is to protect others. Speaking of others, we’ll talk about herd immunity on Thursday.

What are you prepared to do today?

Dr. Chet

 

Reference: https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html

 

The Big Chill: Do You Need a Flu Shot?

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In this final installment of The Big Chill, I’m going to take a look at flu shots: should you get one or not? Before I do that, a word about echinacea.
Echinacea
Many readers have read that echinacea shouldn’t be used long term or used at all if you have an autoimmune disease such as rheumatoid arthritis. The problem is that there are no studies to support either position and no studies to suggest it’s harmful, either. In that situation, the approach is always to proceed with caution until we know more. The only problem with waiting . . .

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The Big Chill: Immune-Boosting Supplements

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Getting ready for cold and flu season, let’s turn to dietary supplements that may help keep your immune system strong. Dozens of supplements are promoted to strengthen the immune system, but let’s stick to what I know works based on the research and my experience: echinacea, garlic, and vitamin C.

Make sure you read this first before you go to the amounts of each supplement to take below because in this case, close enough is. Don’t obsess about the difference between 200 mg or 250 mg, and if I say 300 mg three times a day, don . . .

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If you're already a DrChet.com Member or Insider, click on the Membership Login link on the top menu. Members may upgrade to Insider by going to the Store and clicking Membership; your membership fee will be prorated automatically.