In 1918 an influenza virus ripped through the world. Commonly called the “Spanish Flu”, the death totals were huge. The equivalent deaths worldwide today would have been over 115 million, and over 2 million deaths in the US.
What was particularly unusual is that the vast majority of those deaths occurred in people between the ages of 20 and 40.
The virus was extremely lethal; young healthy men and women who showed signs of the disease in the morning often were dead by the end of the day. Hospitals were unable to keep up with the deaths and had few if any potential therapeutics to reverse the symptoms.
Epidemiologists have tried to understand this result.
The most likely explanation of this strange distribution of mortality is that people who were over 40 had probably been infected earlier in their life with a similar, less lethal version of the influenza virus and that the established immunity was able to at least prevent their deaths, while those under 40, having no immunity at all, were susceptible to dangerous and potentially fatal disease.
So, what can be learn from this and apply those learnings to our current situation with COVID-19?
(Note: I have no data to support this proposition, it is my personal speculation)
We can see potential parallels in the COVID-19 pandemic last year and this year.
The data last year was that young children, if infected with COVID-19 were able to tolerate the infection quite well with either subclinical or mild infections. Likewise, young adults between 20 and 40 were also able to tolerate infection.
The data this year is quite different; we are seeing increased infections, increased hospitalizations and increased deaths in both school-age children and young adults.
WHY?
We know that multiple strains of coronaviruses have circulated in school-age children for years and years, often responsible for the “colds” that keep them home from school for a few days.
We also know that parents are often infected with those “colds” that their children have brought home from school.
Suppose that prior infection with circulating coronaviruses provided a low level of protection against COVID-19, not necessarily from getting infected, but from suffering severe disease. That would explain why last year, school children and their parents were unlikely to require hospitalization from COVID-19 infection.
That protection may well have had a limited time frame and the protection may have waned during the year in which children were held out of school, masked and protected at home. Certainly, we know that the number of “colds” circulating was dramatically reduced.
That result has now changed. If, in fact the protection has waned, then school-age children are now at risk of severe infection, and if they bring the virus home, their parents would be equally more at risk. And this is what we are seeing in the hospitals today.
When considering whether we should be protecting children in schools with masks it is critical to consider whether those children are at higher risk for hospitalization and death this year than last, and whether their unvaccinated parents are also at a higher risk of hospitalization and death.