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.