Covid Likely To Become Endemic

Nature magazine, one of the top two science journals in the world, did a survey of 100  immunologists, infectious-disease researchers and virologists working on the coronavirus, asking if they thought that the virus would become endemic in the human population. Ninety percent of them said they thought it would. From just the mathematics of it, and the fact that it’s everywhere in the world now, I agree with that. I don’t see how it can be otherwise.

But that doesn’t mean that our current situation continues. People will be vaccinated; some will acquire immunity by being infected (although current guidance is that they should be vaccinated anyway); and more will continue to die. As immunity spreads, we will be able to relax social precautions, probably this summer or later. We will, perhaps in a couple of years, be able to go back to something like normal.

We don’t know enough about immunity – how long it lasts and how robust it is to variant strains of the virus – to be sure about timing and exactly what “something like normal” will look like. It is likely to include vaccination against SARS-CoV-2, probably as one of the childhood vaccinations.

To understand why we’ve been hit so hard by this virus and why it’s possible to envision something like normal, think about what would happen if measles suddenly appeared out of nowhere, a new virus to which humans had no immunity.

Measles has an incubation period of 11 or 12 days and is transmitted through the air. Children under 5 and adults are more likely to have complications, which include bacterial ear infection, inflammation of the voice box (larynx) or inflammation of the inner walls that line the main air passageways of your lungs (bronchial tubes), pneumonia (particularly in people with compromised immune systems), encephalitis (which may occur right after measles or months later), and problems in pregnancy, including preterm labor, low birth weight and maternal death.

These complications have low occurrence rates, but if large numbers of people are infected, many will suffer complications.

So introduction of measles into a population that had never seen it would look a lot like the SARS-CoV-2 pandemic. It would spread quickly, there would be arguments about needing masks and when to open schools and bars, and it would present varying symptoms of different degrees of severity in different people. Some would have long-lasting effects. Death rates are hard to pin down precisely for any disease, but it looks like measles is less deadly than SARS-CoV-2. Still, large numbers of deaths would occur.

But humans have lived with measles – it has been endemic – for hundreds of years. It probably came to us from cattle. Babies are born susceptible to it, which is why we vaccinate infants. Adults who have been infected or vaccinated are immune.

This is what will happen with SARS-CoV-2. Most of humanity will become immune. We don’t yet know how frequent immunizations will need to be. There will be occasional cases.

Smallpox has been eliminated in the wild. Like measles and polio, it has no animal reservoir. Polio has almost been eliminated, but the pandemic has interfered with progress. Vaccine deniers and other factors make it unlikely that measles can be eliminated any time soon.

SARS-CoV-2 has animal reservoirs. How plentiful they are will affect its control once it calms down to endemic status. We will not eliminate it for a very long time, if ever.

Cross-posted to Balloon Juice

One comment

  1. The Blog Fodder · February 18

    You are likely right though no one wants to hear it. Vaccines will be developed that work better than what we now have and perhaps will be given to the very young. Or like the flu, we will need shots every year and some will still get it and some will still die from it. Life goes on with one more risk added. Some days I am glad I am old.


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