COVID-19 could behave like other common cold coronaviruses for years to come, particularly affecting young children who have not yet been vaccinated or exposed to the virus, according to a pilot study published today.
The US-Norwegian team noted that because the severity of COVID-19 in children is generally lower, the overall burden of this disease is expected to decrease as the SARS-CoV-2 virus becomes endemic in the global population.
“After infection by SARS-CoV-2, there is a clear signature of progressively more severe consequences and fatalities with age,” said Ottar Bjornstad of the University of Oslo in Norway.
“Still, 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,” he said.
The study, published in the journal Science Advances, noted that such shifts have been observed in other coronaviruses and influenza viruses as they emerged and then became endemic.
“Historical data on respiratory disease indicate that patterns of age incidents during virgin epidemics may be very different from endemic circulation,” said Mr Bjornstad.
For example, ongoing genomic research suggests that the 1889-1890 pandemic, also known as the Asian or Russian flu – which killed a million people, mostly adults over the age of 70 – may have been caused by the emergence of the HCoV-OC43 virus, which is now an endemic, mild, repetitively infecting cold virus that mainly affects children aged 7-12 months,” he said.
However, Mr Bjornstad cautioned that if immunity to SARS-CoV-2 reinfection among adults declines, the disease burden in that group could remain high, although previous exposure to the virus would reduce disease severity.
“Empirical evidence from seasonal coronaviruses indicates that prior exposure only confers short-term immunity to reinfection, allowing for recurrent outbreaks. This prior exposure may prime the immune system to provide some protection against serious illness,” said Mr Bjornstad.
“However, research on COVID-19 shows that vaccination offers stronger protection than exposure to the SARS-CoV-2 virus, so we encourage everyone to get vaccinated as soon as possible,” he explained.
The team developed a “realistic age-structured (RAS) mathematical model” that integrates demographics, the degree of social mixing, and the duration of infection-blocking and disease-lowering immunity to explore possible future scenarios for age incidence and mortality for COVID-19.
The researchers analyzed the disease burden in the short, medium and long term – 1, 10 and 20 years, respectively.
They also examined the burden of disease for 11 different countries – China, Japan, South Korea, Spain, UK, France, Germany, Italy, US, Brazil and South Africa – which differed widely in their demographics.
The team used data from the United Nations for each of these countries to parameterize the model.
The team’s model assumes that the reproduction number (R) — or level of portability — on any given day is linked to the amount of mobility on that day.
The model also encompasses a variety of immunity scenarios, including both independence and dependence on disease severity from previous exposure, as well as short- and long-term immunity.
“For many infectious respiratory diseases, the prevalence increases in the population during a virgin epidemic, but then decreases in a decreasing wave pattern as the spread of the infection unfolds to an endemic equilibrium over time,” said Ruiyun Li, a postdoctoral fellow. researcher at the University of Oslo.
“Depending on immunity and demographics, our RAS model supports this observed trajectory. It predicts a strikingly different age structure at the start of the COVID-19 epidemic compared to the eventual endemic situation,” he added.
The researchers noted that in a scenario of long-term immunity, permanent or at least 10 years, young people are predicted to have the highest infection rate, as older individuals are protected from new infections from previous infection.
Jessica Metcalf, an associate professor at Princeton University, USA, noted that this prediction is likely to hold only if reinfections cause only mild illness.
However, the mortality burden over time may remain unchanged if primary infections do not prevent reinfections or reduce serious illness in the elderly, she added.
(This story was not edited by NewsMadura staff and was generated automatically from a syndicated feed.)