Tag Archive for: vaccination

Are Prenatal Vaccinations Safe?

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Vaccinations for infants and children always inspire debate. Sometimes, fierce debate. Today I’m going to look at a study that examined whether it’s safe for pregnant women to get the tetanus, diphtheria, and acellular pertussis (Tdap) vaccination or if it increases the risk of autism spectrum disorder (ASD) in their babies.

Researchers examined the records of over 81,000 mothers and offspring who were continuously in the care of the Kaiser Permanente Southern California Hospitals. They determined which pregnant women were vaccinated with Tdap. Those women and their children along with the women who were not vaccinated with Tdap and their children were monitored for four to seven years.

The rate of ASD diagnosis was 1.4% of the total subjects. The rate for the children was 3.78 out 1,000 per year for those who were exposed to the vaccination and 4.05 per 1,000 per year for those who were not. In other words, there was no impact on the children of the Tdap vaccination during pregnancy. The researchers concluded that the use of Tdap vaccinations was supported during pregnancy.

But my focus isn’t really on the use of vaccinations; you can look at the data and decide for yourself. It’s on the controversy around vaccinations.

Debate is good, especially as it relates to health, and nothing inspires more debate than vaccinations. But are all debates a real discussion of the issues or are they an attempt to create discord? A recent study may give us some insight. More on that Thursday.

What are you prepared to do today?

Dr. Chet

 

Reference: PEDIATRICS 14(3) September 2018:e20180120

 

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

 

A Reasonable Discussion

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I spent the past weekend with thousands of people in Peoria. It’s always refreshing to talk face-to-face and answer questions. Occasionally I’m challenged, but I don’t mind because it forces me to do more research to find answers for things I don’t know. But it’s not the science that presents the biggest challenge; it’s the people interpreting the science that’s the challenge. I’m going to use what I read and saw Monday morning to help illustrate the issue.

I’ll begin with a network TV morning show. The show did . . .

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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 . . .

We're sorry, but this content is available to Members and Insiders only.

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.