Children are at risk of “immunity debt”. Credit: Pixabay, sweetlouise
The Covid-19 pandemic may be behind us, but its effects are still evident across Europe. In the aftermath, countries are seeing an increase in viral infections, particularly among children and teenagers.
Are these infections a cause for alarm, or is it a natural consequence of our post-pandemic world?
The surge in viral infections across Europe
In Denmark, cases of Mycoplasma Pneumoniae, a bacterium responsible for respiratory infections, have surged. The 2023-2024 season saw a threefold increase in infections compared to pre-pandemic years, and hospitalisations rose 2.6 times, according to a report on The Lancet.
Despite this uptick, the severity of infections hasn’t worsened, indicating that while more people are getting sick, they’re not necessarily experiencing more severe symptoms.
England, Germany and France have also reported higher incidences of respiratory syncytial virus (RSV) in recent years. As Dr. Peter Openshaw, a respiratory doctor from Imperial College London, told Euronews: “There has been quite a bounce-back in a number of these infections which were not circulating significantly for a good winter or two, and they came back with quite a vengeance.”
What is immunity debt?
The concept of “immunity debt” has been frequently discussed as an explanation for this surge in post-pandemic infections. During the height of the pandemic, non-Covid illnesses saw a significant drop due to widespread restrictions such as social distancing, frequent handwashing, and reduced social interaction. These preventative measures led to the temporary suppression of many common viruses.
Some viruses, like certain flu strains, disappeared during this period, while others re-emerged once restrictions were lifted. This phenomenon, known as “immunity debt”, refers to the delayed exposure to viruses, resulting in more people being susceptible to infection when normal social interactions resumed.
The term “immunity debt” has sparked debate, particularly around the notion that natural infections are better for immunity than vaccines. Some critics suggest that the concept implies pandemic restrictions were unnecessary because people eventually got sick anyway. However, Dr. Openshaw disproves this, telling Euronews that public health measures “saved many, many thousands, possibly millions of lives.” The post-pandemic rise in infections, he adds, was largely inevitable.
RSV and immunity debt
Respiratory Syncytial Virus (RSV) offers an example of immunity debt supposedly in action. Most children typically contract RSV by age two, but during the pandemic, babies were kept away from others, delaying their exposure. Once restrictions eased, the virus spread quickly among those who had never encountered it before. However, this delay may not be entirely negative, as RSV is particularly dangerous for infants under six months old. Dr Amesh Adalja, an infectious disease doctor and senior scholar at the US Johns Hopkins Center for Health Security, told Euronews, “Each human owed their debt to RSV, and it just got delayed. The debt collector was coming.”
Are all viral infections linked to immunity debt?
While immunity debt explains much of the increase in viral infections, it doesn’t account for everything. For instance, France experienced its worst outbreak of whooping cough in 25 years earlier this year.
However, this rise is more likely due to cyclical trends rather than immunity debt, as whooping cough outbreaks tend to occur every three to five years. Similarly, schools in Spain have been hit by whooping cough outbreaks, highlighting the risk to children.
Surging viral infections and the impact on healthcare systems
One of the most concerning aspects of this rise in infections is the strain it places on healthcare systems. In 2021, European paediatric societies called for stronger childhood vaccination programmes to counter the effects of immunity debt. In response, new vaccines, including RSV vaccines for pregnant women and older adults, have been rolled out across the European Union and the UK.
“Vaccines are a great way of filling the gap in immune stimulation which was left by a reduced rate of virus circulation,” Dr. Openshaw told Euronews.
However, the sharp increase in viral infections could overwhelm hospitals already struggling with staff shortages. According to Openshaw, “We’re still seeing an awful lot of hospital attendances, serious illness with these viruses because they’re circulating at a higher-than-previous level.”
As countries head into the winter season, the risk of viral infections remains high. While vaccination programmes offer hope, the strain on healthcare systems means it’s more important than ever to take preventative measures, especially for those with young children or vulnerable family members.
