The following essay is reproduced with permission from The Conversation, an online publication covering the latest research.
Every fall and winter, viral respiratory illnesses like the common cold and seasonal flu prevent children from going to school and participating in social activities. But this year, more children than usual are ending up in emergency departments and hospitals.
In California, the Orange County Health Department declared a state of emergency in early November 2022 due to record numbers of pediatric hospitalizations for respiratory infections. In Maryland, emergency rooms are running out of beds due to unusually high numbers of respiratory syncytial virus, or RSV, infections. Emergency departments must therefore refer patients across state lines for care.
In the United States, the winter respiratory virus season started earlier than usual this year. Given that infection peaks usually occur in late December or January, this unusual early wave suggests the situation could worsen for people of all ages, especially children.
We are epidemiologists specializing in epidemic analysis of emerging disease threats, including respiratory infections. We closely monitor the patterns of these infections and pay close attention when the patterns are unusual. We are increasingly concerned about the number of pediatric hospitalizations in recent months and the emerging trend.
The “triple threat”
In early November, the Centers for Disease Control and Prevention issued a health advisory regarding increased activity of respiratory infections, particularly in children. The CDC and other health experts warn of the so-called “triple threat” of respiratory illnesses from RSV, influenza — or seasonal flu — and COVID-19.
The underlying reasons for the convergence of these viruses and the increase in infections so early in the season are not yet clear. But health experts have some clues about the contributing factors and what it could mean for months to come.
With respect to COVID-19, 2022 is expected to usher in another winter wave of infections, similar to patterns seen in 2020 and 2021. Previous winter waves resulted from a combination of factors, including the emergence and spread of new viral variants, more people gathering indoors rather than distant outdoors, and people gathering for the holidays.
But unlike previous pandemic winters, most COVID-19 precautions — like using masks in public spaces or avoiding group activities — are more relaxed than ever. With the looming threat of new variants, it is difficult to predict how big the next wave of COVID-19 might be.
And while the seasonal flu has proven somewhat unpredictable during the COVID-19 pandemic, it almost always strikes in late October. Flu season has also arrived about a month earlier and in greater numbers than in recent history. From our reading of the data, pediatric flu hospitalizations are almost 10 times higher than what has been seen at this time of year for more than a decade.
RSV infections tend to follow a seasonal pattern similar to influenza, peaking during the winter months. But this year, there was an unexpected summer surge, long before the start of the typical fall respiratory virus season.
In typical years, RSV attracts little media attention. It’s incredibly common and usually only causes mild illness. In fact, most children encounter the virus before the age of 2.
But RSV can be a formidable respiratory infection with serious consequences for children under 5, especially infants. It is the most common cause of lower respiratory tract infections in young children, and more serious illnesses can lead to pneumonia and other complications, often requiring hospitalization.
Why children are especially at risk
Children, especially young children, tend to get sicker from influenza and RSV than other age groups. But infants under 6 months suffer the most, with nearly double the risk of death from RSV compared to other children under 5. Hospitalization rates for COVID-19 are also four to five times higher for infants than for older children.
One of the reasons younger children are more at risk is that their immune system is not yet fully developed and does not produce the robust immune response seen in most adults. Additionally, infants under 6 months old — who are most at risk of severe illness — are still too young to be vaccinated against influenza or COVID-19.
These viruses present challenges on their own, but their co-circulation and simultaneous increases in infections create a perfect storm for multiple viruses to infect the same person at once. The viruses might even act together to evade immunity and damage the respiratory tract.
Such co-infections are generally rare. However, the likelihood of co-infection is significantly higher in children than in adults. Co-infections can be difficult to diagnose and treat, and can ultimately lead to greater disease severity, complications, hospitalizations and death.
Factors behind the Triple Threat
There are several reasons why the United States could see an increase in pediatric respiratory infections. First, protective strategies against COVID-19 actually help prevent the transmission of other respiratory pathogens. School and daycare closures have likely also minimized children’s exposure to various respiratory viruses.
These and other efforts to prevent the spread of COVID-19 appear to have suppressed the wide circulation of other viruses, including influenza and RSV. As a result, the United States has seen an overall drop in non-COVID respiratory infections — and an almost non-existent flu season in winter 2020.
Decreased viral activity means that children have missed out on some exposures to viruses and other pathogens that typically help boost immunity, especially in the early years of life. The resulting so-called “immune debt” may contribute to an excess of pediatric respiratory infections as we continue this season.
To further complicate the picture, the changing nature of viruses, including the emergence of new variants of COVID-19 and the natural evolution of seasonal influenza viruses, means we could see a unique combination of particularly transmissible strains or strains that cause more serious illnesses.
Proactive steps people can take
The early resurgence of respiratory infections with high rates of hospitalization underscores the importance of prevention. The best tool we have for prevention is vaccination. Vaccines that protect against COVID-19 and influenza are available and recommended for anyone over 6 months old. They have been shown to be safe and effective, and they can and do save lives.
In particular, the most recent data on the recently updated bivalent COVID-19 booster vaccine suggests that it produces a more rigorous antibody response against current circulating omicron variants than the original COVID-19 vaccines.
The best way to protect infants under 6 months against influenza and COVID-19 is to vaccinate them during pregnancy. When a pregnant mother is vaccinated, maternal antibodies cross the placenta to the baby, reducing the risk of hospitalization for COVID-19 in young infants by 61%. Immunizing other caregivers, family and friends can also help protect infants.
Other preventative measures, such as washing hands, covering sneezes and coughs, staying home, and isolating yourself when sick, can help protect the community from these and other viruses. Paying attention to local public health advisers can also help people have the most up-to-date information and make informed decisions to keep themselves and others safe – of all ages.
This article originally appeared on The Conversation. Read the original article.
