What Is Immunity Debt and How May It Affect Kids?

A father helping his son blow his nose
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Just when it felt like the resumption of regular life was on the horizon, parents are being warned of a new threat to their children’s health. Doctors have expressed concern that a surge in common illnesses—such as respiratory syncytial virus (RSV) and seasonal influenza—could be around the corner. This is due to what is being called an "immunity debt," a phenomenon caused by the non-pharmaceutical measures taken to combat COVID-19.  

Doctors fear that as COVID-19 restrictions end, so too will the temporary suppression of illnesses such as RSV, chickenpox, strep throat, flu, and more, potentially causing further epidemics down the line.

What Is Immunity Debt?

According to a study conducted in France, an immunity debt is caused by a lack of exposure to regular bacteria and viruses. All the measures taken to suppress the spread of COVID-19, such as social distancing, increased hand-washing, and sanitizing, also helped stop the circulation of other common illnesses. While it was beneficial in the short term to see the case numbers of viral diseases drop, they are expected to surge as children return to school and childcare settings.  

“Children naturally build immunity to microbes, especially viruses, when they get exposed to them,” says Nkeiruka Orajiaka, MBBS, MPH, an emergency room pediatrician at an ER in Columbus, Ohio, noting that this typically happens from close contact with other kids in places like daycare, schools, or playgrounds. However, building immunity through normal contact was halted when the COVID-19 restrictions were put in place. “Hence, most kids experienced an immunity debt, or a lack of immune stimulation due to these reduced exposures,” explains Dr. Orajiaka. “Now, these kids are experiencing a surge in these infections and are getting sicker with exposure to these viruses.”

Robert Cohen, MD, PhD

It is important to understand that non-pharmaceutical measures taken to reduce the burden of the pandemic have also reduced a number of infectious diseases in adults but more so in children.

— Robert Cohen, MD, PhD

Prior to the pandemic, for most children, contact with common infections were not necessarily followed by illness, explains Robert Cohen, MD, PhD, a professor and infectious disease specialist from a pediatric center near Paris who co-authored the study on immunity debt. But without the natural circulation of viruses such as RSV, chickenpox, strep throat, flu, and more, children have been unable to build up any immunity against them. “The non-pharmaceutical measures we have taken have reduced the circulation of the virus and also bacteria," Dr. Cohen says, noting that his concern is that once COVID-19 restrictions end, infectious diseases will spread freely as the reservoir of children unimmunized against them is very large.

What Can We Expect This Flu Season?

To see the effects of a largely unimmunized community, we need only look to New Zealand. After recording just five cases of RSV in May, the country is now in the grips of a significant outbreak. At its peak at the end of July, which is mid-winter in the Southern Hemisphere, the country recorded almost 1,000 cases.

Many hospitals across the U.S. have already experienced an uptick in RSV cases, which is uncommon for this time of year. “The typical season for RSV, flu, and other viruses are between fall and winter, with a few spilling into spring,” says Dr. Orajiaka. “However, with precautions in place for COVID-19 last fall and winter, overall infection volumes for these viruses were low. These viruses are seen now in very high numbers with a lot of hospitals experiencing high volumes of both severely sick and mildly infected children." She also notes that this significant spike is partly fueled by the recommendation by the Centers for Disease Control and Prevention (CDC) to test as many kids as possible for RSV.

“As we slowly see an increase in RSV and rhinovirus, it may not be far-fetched to expect infection spikes with the flu virus," warns Dr. Orajiaka. "This may occur earlier as kids start going back to school. If there is any season to be very prepared, it will be this season.”

Who Is Most At Risk?

RSV symptoms are usually mild but can cause serious infections, such as bronchiolitis and pneumonia. Infants under 12 months (particularly premature infants), the elderly, and those with weakened immune systems are especially at risk. “Protect young infants,” advises Dr. Cohen. “Approximately half of the patients hospitalized for bronchiolitis caused by RSV is before six months of age.”

Dr. Orajiaka notes that children with any chronic medical problems such as lung or heart disease are particularly high risk, too. “Also in consideration would be kids who had never been in daycare or structured school systems or a group of other kids prior to the lockdown," she says. "This is because they never had the opportunity to interact with other kids and get exposed to these normally circulating viruses.”

How To Keep Children Protected

The most effective way of keeping your children protected against the spread of infections is for the whole family to stay as healthy as possible. That means avoiding friends, colleagues and even other family members if they (or you) are unwell. Maintain a safe social distance from others when in crowded places, avoid touching your face and wash or sanitize your hands after touching common surfaces. Here are some other practical ways to help keep illness at bay:

Vaccinate

While there currently is no vaccine against RSV, there are other vaccinations available. Shots for varicella (more commonly known as chickenpox), rotavirus, pertussis (whooping cough), and meningococcus are all on the vaccination schedule for the U.S. If your child is eligible, they should all get the COVID-19 vaccine. “Every family should vaccinate themselves and their older children for the COVID-19 vaccine and then the flu vaccine when it becomes available,” says Dr. Orajiaka.

Mask Up

“I highly recommend every child older than two years of age and developmentally appropriate should wear a mask to school always and to other public settings,” says Dr. Orajiaka. While this does a great job protecting these unvaccinated groups from COVID-19, they will also be protected from this new surge of viruses.

Wash Hands

RSV, like most other viruses, is highly contagious and spreads through droplets in the air when someone coughs or sneezes. It also lives on surfaces, like door handles, mobile phones, or countertops. It is a good idea to continue to practice good hygiene. Wash your hands frequently and apply hand sanitizer.

Decontaminate

Stem the spread of viruses by limiting the exchange of food or other personal items, says Dr. Orajiaka. If you have anyone particularly vulnerable in your house, you will need to take extra steps to protect them. "Parents should have a decontamination plan in place when kids get home from school," Dr. Orajiaka says. This could include changing out of the clothes they wore to school and cleaning any objects brought home with an anti-bacterial wipe.

Boost Your Immunity

Give yourself and your kids a fighting chance this flu season with a healthy immune system. You can boost yours by exercising, getting enough sleep, and eating a healthy diet to help your body maintain its natural immunity, says Dr. Orajiaka.

A Word From Verywell

With respiratory viruses like RSV already on the rise and in the face of warnings against the further spread of other diseases, it is natural to worry about the health of your children right now. However, with some preparation—such as getting vaccinated and naturally boosting your immune system ahead of flu season—there are practical ways of protecting the whole family.

As a parent, it is also a good idea to become familiar with the symptoms of different viruses, says Dr. Orajiaka, who urges parents to pay particular attention to children under 3 months old. "Children younger than 3 months old are at risk of breathing pauses (apnea) with RSV infection so families should be highly cautious."

If your child is having difficulty breathing, is not drinking any fluid, or is experiencing new or worsening symptoms, call your healthcare provider immediately. If you suspect your child might be at high risk for RSV, call your healthcare provider to discuss.

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  2. Henderson J, Hilliard TN, Sherriff A, et al. Hospitalization for RSV bronchiolitis before 12 months of age and subsequent asthma, atopy and wheeze: A longitudinal birth cohort study. Pediatr Allergy Immunol. 2005;16(5):386-392.

  3. Kulkarni H, Smith CM, Lee DDH, Hirst RA, Easton AJ, O’Callaghan C. Evidence of respiratory syncytial virus spread by aerosol. Time to revisit infection control strategies? Am J Respir Crit Care Med. 2016;194(3):308-316.