Immunity Debt: When the Bill Comes Due

Other than Covid-19, we haven't seen many respiratory illnesses over the past two years. Now we're paying the debt that accrued over time.

We’re so pleased to welcome back pediatric hospitalist, Dr. Eliza Holland, an #UrgencyOfNormal team member! Eliza’s previous post, Camp Covid was about the personal costs of overly restrictive summer camp policies. Here, she focuses on “Immunity Debt,” which is caused by a lack of exposure to benign pathogens, bacteria and other viruses. Some experts warn about new, harsher impacts of Flu, RSV & other common illnesses due to the many layers of mitigation that were applied so broadly over the past two plus years.

Not so long ago, bacterial diversity was all the rage. In 2013, Michael Pollan had written the popular and eye-opening article Some of My Best Friends Are Germs, world-renowned microbiologist Martin Blaser was revered by the media for his brilliant look at antibiotic overuse Missing Microbes, and ecologist Jack Gilbert was advising parents to let kids play outside -and together- in his book Dirt is Good. We considered the risks of too much time spent in the built environment and even floated the idea of building a global bank of germs.

But then the pandemic changed everything, and the abysmal messaging about risk, reward and the benefits of normal interaction was terrible for our children’s mental and physical health. VA Tech aerosol scientist Linsey Marr, for example, infamously advised that during Thanksgiving 2021, “You could have the kids wear masks, eat quickly and stay away from the older adults when eating.” We strayed so far from what parents innately knew to be healthy because of medical “experts,” who admonished us to isolate, stick screens in our kids’ faces, mask, distance and sanitize when outside and gathering in public.

But all is not lost. We can still correct course. Get outside, play sports, socialize with friends, eat fresh and healthy foods! Our kids - and their parents - are resilient- we just need to make sure to trust intuition and a few very carefully selected medical “experts” here and there.

Eliza Holland is one of those. Please read and share her post and make sure to follow her at @etholland71.

-Natalya & Dana

A pediatric resident recently sent me a Today.com article which breathlessly announced that children’s hospitals are full due to respiratory illnesses occurring earlier than expected and presenting with more severe symptoms than usual. As a pediatric hospitalist, I am definitely seeing larger numbers in our children’s medical center.  But it is important to remember that this spike of non-Covid illnesses was expected after the Covid mitigation measures, such as school closures and physical distancing, were lifted. We have not seen many other respiratory illnesses over the past few years and we are now paying the immunity debt that accrued during that time.

Respiratory syncytial virus (RSV) is one of many viruses that cause colds and breathing problems in children. Pre-Covid, it was estimated that all children had seen RSV at least once by the age of 2.  It is most severe in children under 6 months of age and those with underlying heart and lung problems. Older children are often spared hospitalization because of prior infections. In the US in 2016, RSV hospitalized about 58,000 children per year and accounted for 17% of hospitalizations for children under the age of 2. RSV also causes significant illness in patients over 65 and those with heart and lung issues, causing 170,000 hospitalizations and 14,000 deaths per year in the US. However, due to distancing and increased hygiene measures, RSV and many other viral infections spread less effectively during 2020 and 2021. This was good news at the time because it freed up hospitals to care for sick Covid patients. It is now bad news because exposure to the common respiratory viruses is how we build immunity and prevent severe infection on re-exposure. In other words, our immune system needs to see the viruses in order to protect us against later infections. 

It is also likely viral interference, not the easing of mask mandates, is playing a role in the unusual timing of RSV and other respiratory viruses. The theory behind viral interfence is that infection with one virus can provide some temporary protection against a second virus. This was seen during the 2009 H1N1 influenza pandemic when the RSV season was delayed up to 2.5 months after its expected start. There was a late RSV season in 2021 that coincided with a decrease in Covid cases over the summer. As Covid cases have again been declining over this fall, we are seeing an increase in RSV cases and in flu cases in a population with limited prior exposure and immunity. This scenario was predicted by French researchers last summer, “Low viral and bacterial exposures due to NPIs imposed by the COVID-19 pandemic raise concerns as we may witness strong pediatric epidemic rebounds once personal protection measures are lifted.”

San Diego schools are struggling with these viral rebounds right now.  One school reported 40% of the students absent, another 35%. One doctor interviewed for the article stated he is “seeing kids of all ages getting sick right now with things other than Covid and says part of the reason is lack of immunity.” As you are deciding whether or not to mask your student, it is important to keep in mind that the CDC has not recommended community masking as a mitigation measure for viruses such as RSV and influenza.

Another factor in the filling of beds in children’s hospitals is that pediatric wards across the country are being shuttered for financial reasons.  Pediatric wards are not as profitable as adult units. This is not only happening in smaller towns but in cities like Raleigh, North Carolina and Colorado Springs and to well-known centers such as Tufts Children’s Hospital in Boston. With fewer pediatric beds available, more children are sent to the remaining pediatric hospitals which stresses capacity.  This plus the immunity debt creates the perfect storm we are in now.

Routine respiratory viruses are a known and necessary part of childhood for healthy children. One study followed a young child, in daycare and with an older sibling, for 27 months and tracked viral illness. This child was tested for viruses each time she displayed fever, runny nose, or cough, for a total of 196 swabs!

So what are parents to do with this information? Go back to the basics - good handwashing, staying home when ill, avoiding sick contacts, and getting a flu shot can help prevent infection in those who are at high risk. Masking will not stop the spread, the return of school closures and physical distancing will only prolong the inevitable viral illnesses.

As we are seeing now, the immunity debt is always waiting to be paid.

Eliza Holland, MD is a pediatric hospitalist in Charlottsville, Virginia.  She is a member of Urgency of Normal, a collaborative group of doctors and scientists advocating for children’s well being and an urgent return to fully normal life and schooling.

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