Children develop weaker antibodies to coronavirus than adults do, new research suggests.
Scientists at Columbia University believe that children actually recover so quickly that they typically don’t get seriously ill, or develop a particularly significant reservoir of antibodies for COVID-19.
But that may not mean that kids are any more vulnerable to reinfection than adults are, experts say.
And the findings may be biological evidence that children also remain contagious for a shorter period of time than adults.
Children develop fewer, weaker coronavirus antibodies to coronavirus – but they are likely still protected, a new Columbia University study found (file)
The sheer number of U.S. children with COVID-19 has increased dramatically in recent weeks, with a record 61,000 children infected last week, according to the American Academy of Pediatrics.
But coronavirus does not seem to pose nearly as dire a threat to the vast majority of kids as it does to adults.
As of Wednesday, the Centers for Disease Control and Prevention (CDC) had recorded 110 COVID-19 deaths among children under 18.
There is nothing insignificant about the deaths of children, but those fatalities represent just 0.02 percent of the 663,797 infections among the same age group.
Although coronavirus triggers a potentially life-threatening condition, known as MIS-C (multisystem inflammatory syndrome in children) in some kids, most just don’t get very sick.
And the results from the new Columbia study backs up observations that children don’t stay sick or contagious with COVID-19 as adults do.
Researchers there analyzed plasma – the immune cell-rich, clear component of blood – from 32 adults and 47 children that came to two hospitals in New York City at the height of the pandemic there.
Sixteen of the kids had been hospitalized with MIS-C. The other had mild or asymptomatic cases of COVID-19.
Thirteen of the adults had to be hospitalized, while the rest were outpatient visitors who tested positive.
Adults (left) maintained much higher levels of coronavirus antibodies in their plasma. Children’s antibody levels (right) fell moe quickly, but scientists think the types of antibodies they develop will offer lasting protection
All adult and pediatric patients had immune responses to the infection, but these varied very clearly based on which age group a person fell into.
‘We found that children had a very distinct type of response,’ lead study author Dr Donna Farber told DailyMail.com.
She explained that there are a handful of different types of antibodies, and which ones develop in what quantities can tell scientists a lot about what kind of infection and protection a patient will have.
Both adults’ and children’s plasm contained immunoglobulin G (IgG), a type of antibody that develops later in the course of infection and are more likely to confer lasting immune protection.
Adults also had immunoglobulin M (IgM), a type of antibody that forms earlier on in the course of infection. But children had very little of this immune protein.
Children’s plasma also showed fewer signs of antibodies that form in response to fragments of coronavirus proteins that are left scattered in the stream after the virus infects and kills a cell.
‘One explanation,’ for the lack of antibodies to this type of viral shrapnel, ‘is that children are not getting as disseminated an infection,’ said Dr Farber.
‘In a child, you’re not getting as many dying cells and [as much] viral spread.’
Without such widespread infection, children are likely less contagious and Dr Farber says they may not be ‘massive vectors’ of the disease.
Adults had, overall, a ‘higher magnitude’ of immune response, said Dr Farber.
And in children it may be that ‘the magnitude of response being low reflects that they’ve cleared the virus, either through a robust innate immune response, or, the other possibility is that they could have cross-reaction [of antibodies] from other coronaviruses.’
Humans are born with the ‘innate’ defenses against infection she describes, which is full of naive immune cells that are not specially developed against particular pathogens, but are ready and raring to attack whatever invaders may come.
But this first line of defense is not specialized, and wanes over time, so it’s little help to adults.
Children also come into contact with many cold-causing viruses when they’re young, and other coronaviruses account for about 15 percent of all seasonal respiratory viruses.
Adults develop immunity to these, but children’s more recent infections may mean they’re better primed to fight off the new coronavirus.
Dr Farber also thinks that children’s naive T cells – another infection fighter, apart from antibodies may keep coronavirus at low levels.
‘Children are designed to respond and to make new antibodies to new viruses because they have a lot of naive T cells,’ she says.
And despite the lower number of weaker antibody response, she suspects children exposed to coronavirus will be protected long term.
Her hope – and suspicion – is that kids’ coronavirus immunity ‘will just be one these memory responses that these children who have grown up during our pandemic will be protected.’