COVID-19 can just transform into a childhood disease

As adults become immune, the risk of infection will shift to younger, unvaccinated children, researchers predict.

What we know so far about the coronavirus seems to be hitting mainly the elderly population. For example, relatively few children worldwide have contracted COVID-19. However, that could just change in the future. Researchers warn that COVID-19 could transform into a childhood disease in the coming years.

Endemic

Many scientists suspect that the coronavirus is becoming endemic. That means the disease may not go away. In that case, the SARS-CoV-2 virus could behave like other known influenza or coronaviruses that became endemic, mainly affecting young children who have not yet been vaccinated or exposed to the virus. “Historical data on respiratory diseases show that diseases behave very differently during an initial epidemic than when they become endemic,” explains researcher Ottar Bjornstad.

At the moment, mainly older people are getting sick from corona. “After infection from the coronavirus, the likelihood of severe symptoms or death seems to increase with age,” said Bjornstad. “Yet our model results suggest that the risk of infection is likely to shift to younger children as the adult community becomes immune, either through vaccination or exposure to the virus.” In short; as more and more elderly people are protected against a new infection by a previous infection or vaccination, most infections will occur among young people.

Study

In the study, the scientists studied the disease burden in the short, medium and long term – 1, 10 and 20 years, respectively. They also examined the burden of disease for eleven different countries, including China, Japan, South Korea, Spain, the United Kingdom, France, Germany, Italy, the United States, Brazil and South Africa; countries that differ greatly in their demographics. For each of these countries, they used data from the United Nations to parameterize the model. “Thanks to our model, we can make robust predictions about age-related risk,” explains researcher Ruiyun Li.

Disease burden

Because the severity of COVID-19 in children is generally lower, the overall burden of the disease is expected to decrease. However, Bjornstad warns that if immunity among adults declines, the disease burden in that group could remain high. And that would mean that many older people could still die from the disease. While it is true that previous exposure to the virus could reduce the severity of the disease, we should certainly not bet on this, according to the researchers. “Empirical evidence from seasonal coronaviruses shows that prior exposure only provides short-term protection against reinfection,” said Bjornstad. “This can make recurrent outbreaks possible. Research into COVID-19 shows that vaccination offers stronger protection than exposure to the SARS-CoV-2 virus. That is why we encourage everyone to get vaccinated as soon as possible.”

The researchers argue that their model is useful for policymakers and can serve as a powerful and flexible tool. Because thanks to the model, we get a better picture of the future circulation of COVID-19 among different age groups. And that can help to strengthen our preparedness and act in a timely manner. “The mathematical framework we have built is flexible and can help tailor mitigation strategies for countries around the world with different demographic and social patterns,” explains Bjornstad. “This makes it a crucial tool in important policy decisions.”