September 20, 2020

Flu, COVID-19, and Herd Immunity

Vaccines have changed the landscape of infectious diseases over the past 100 years. Polio, smallpox, measles, tetanus, diphtheria, mumps, rubella, and many more are now rare diseases or eradicated altogether. Streptococcal Pneumonia and Hemophilus Influenza, both bacteria, were frequent killers of children, causing meningitis, as well as pneumonia and ear infections. Native Americans were particularly hard hit by these bacteria that are, thankfully, now prevented with immunizations of infants. As the vaccines came into use, I saw cases drop when I worked with the Hopi in the early 90’s. It was remarkable to see the difference the vaccines made. Chicken Pox can be prevented now, as well as cervical and anal cancer by immunizing against HPV. Complications and long term aftereffects of viral infections can be prevented also. They can return to haunt us years later. Sadly, a recently approved vaccine for preventing shingles has had a shortage due to manufacturing delays. This delayed Jamie, my husband, from receiving his vaccine and now he has been struck with an outbreak of shingles. Ouch. Get your vaccine now, if you can. One benefit of the shutdown is the shortage has been resolved and it is available. Get a flu shot while you are at it, more important than ever.

Much research is being conducted into finding an effective and safe vaccination for COVID-19. Scientists are racing world wide to find at least one that is effective. Considering the poor uptake of flu vaccines in the US, I was reassured to see that 70% of people in one survey say they plan to get COVID-19 vaccine when available. That may get us to herd immunity, depending on its effectiveness and how many in your community get the new vaccine.

The Lancet, a prestigious journal from the UK, has an article describing the history of the term “Herd Immunity”. I found it interesting, especially when realizing that it began as a recognition that a disease dies down in livestock when a certain percent have been infected. In a disease like COVID-19, the number of infections needed to reach herd immunity would cause an unacceptable number of deaths. The hope is to get there by immunizations, when we have them. The Lancet acknowledges that calling it “herd immunity” is problematic because of its association with livestock, and wonders if changing the name to “population immunity”might be a better phrase. The percent of the population that needs immunity to protect the herd varies by disease and we don’t know yet what that is for COVID-19. Further, we don’t know how long the effectiveness of the vaccine will last. We are still in limbo.

But there is strong evidence that all the social distancing we did, the mask wearing, and the hand washing, wiped out the flu this past spring. Flu is not as transmissible as SARS-CoV-2 so this data is not surprising. Continuing our social distancing and mask wearing can help cut down on flu as much as COVID-19.

Wash your hands, cover your nose, keep safe six, catch up on your vaccinations.

And finally, my caveat is that this is my experience and my opinions, which are subject to change as more information is available, and not related to the organization I work for. Thanks for reading.