- Covid-19 symptoms tend to be milder in kids, according to studies in Zhejiang and Wuhan, with asymptomatic infections ‘not uncommon’
- But health experts say more investigation into the chain of transmission is needed
Children tend to get less severe symptoms when they contract Covid-19 and cases can be harder to detect than in adults, new research in China has found, as health experts, parents and officials weigh the risks of sending their kids to school.
A study of 36 cases in children in the eastern province of Zhejiang found that 10 " or 28 per cent " had no symptoms, while seven had mild upper respiratory symptoms, according to a paper published in The Lancet Infectious Diseases on Wednesday.
Separate research published this month in The New England Journal of Medicine had similar results. It found that of 171 children who contracted the new coronavirus in Wuhan, where it was first reported in December, 27 " or 15.8 per cent " were asymptomatic, or had no immediate symptoms. Another 12 showed features of pneumonia in their medical scans, but not symptoms of infection.
"The large proportion of asymptomatic children indicates the difficulty in identifying paediatric patients who do not have clear epidemiological information, leading to a dangerous situation in community-acquired infections," the researchers in the Zhejiang study said.
China last week declared it had "basically stopped" domestic transmission of the virus after imposing two months of lockdowns and mass quarantine measures around the country. Several provinces " including Guizhou, Qinghai and Yunnan " have already reopened some schools, and more provinces are preparing to resume classes in early to mid-April. But education authorities in Beijing and the southern province of Guangdong have yet to set a date for schools to reopen.
In Hong Kong, which is bracing for a surge of imported cases, the government has said schools would not go back before April 20.
As the pandemic continues to spread across the globe " with at least 655,000 people infected and more than 30,000 deaths worldwide " other countries have also closed schools and campuses, imposed social distancing measures and in some places total lockdowns to try to curb the contagion.
Canadian medical experts Alyson Kelvin and Scott Halperin said the Zhejiang research pointed to the potential role of children in spreading the virus.
"The most important finding to come from the present analysis is the clear evidence that children are susceptible to infection, but frequently do not have notable disease, raising the possibility that children could be facilitators of viral transmission," they wrote in a comment in the journal.
The study, led by Song Qifa of the Ningbo Centre for Disease Control and Prevention and Chen Dong of Wenzhou Central Hospital, looked at a group of children aged between one and 16 who fell sick from mid-January to the end of February.
The children were all from the cities of Ningbo and Wenzhou and accounted for 5 per cent of the total cases in those places during that period. They had either had close contact with an ill family member or had been exposed to an outbreak area, or both.
Nearly half of them were mild cases and the rest were moderate, and they all recovered after an average of 14 days in hospital. Those with immediate symptoms tended to have a fever and dry cough.
Children may be just as vulnerable to coronavirus as adults, study finds
The researchers found that compared to adult patients in the two cities, the severity of fever, coughs and pneumonia was significantly less in children with Covid-19. They also had a much milder illness compared to children who contracted severe acute respiratory syndrome (Sars) during the 2002-03 epidemic.
"The (new coronavirus) has little effect on the upper respiratory tract of children. Covid-19 is highly transmissible … but can have a covert presentation in children," the researchers said.
"This asymptomatic condition is relevant if community-acquired transmission becomes the primary mode; identification of paediatric patients without … symptoms will become a great challenge."
The separate study in Wuhan carried out by researchers from the city, Beijing and Hong Kong, also found that most children infected with Covid-19 had a milder clinical course than adults.
"Asymptomatic infections were not uncommon. Determination of the transmission potential of these asymptomatic patients is important for guiding the development of measures to control the ongoing pandemic," they said.
The Canadian experts cautioned that more investigation into the role of children in the chain of transmission was needed. But they said if children were found to have an important role in spreading the virus, governments should take this into account in policies to slow transmission and protect the vulnerable.
Online classes in coronavirus-hit China leave kids without Wi-Fi struggling
But other experts were concerned about the toll of school closures on children, especially disadvantaged students who may not be able to access distance learning through online platforms.
"School closure measures should consider epidemiological evidence and avoid exacerbating inequities, providing learning without digital technologies, childcare alternatives, and health care," Richard Armitage and Laura Nellums of the University of Nottingham's epidemiology and public health division, wrote in The Lancet Global Health.
"Authorities should implement strategies to reduce transmission within schools before or instead of closures, including smaller class sizes, physical distancing, and hygiene and sanitation promotion."
In China, parents had mixed feelings about schools reopening.
Xu Zhen, whose 11-year-old daughter is still staying home in Wuxi, Jiangsu province, said the contagion risk was likely to be low when primary schools go back next month.
"Our city hasn't had any new patients for weeks, and we haven't reported any imported cases so far. I think the situation is under control," she said.
"Actually, I really can't wait " I think I'll collapse soon watching my daughter having online classes every day. She's so absent-minded, listening to the teacher while she plays with the cat."
But for Shen Juan, it was too soon to send her seven-year-old son back to school in Beijing. The city's health commission said nearly 95 per cent of its local cases " about 400 " had recovered, but there had been a recent spike in imported cases, which stood at more than 150.
"The real situation may not be as good as the official figures suggest " the reporting system involves many levels and there may be loopholes or misreporting," Shen said.
"I won't send my son back to school until the 'two sessions' open," she said, referring to China's postponed annual political meetings, which were due to be held in early March. Beijing has yet to set a new date for the gatherings.
"Only when the officials and cadres dare to gather can we draw the conclusion that China is safe," Shen said. "I won't send my child to school before that day."
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