Children’s immune systems are better at recognising the coronavirus as a threat, helping to explain why they suffer less severely from Covid-19, research has found.
Scientists said children’s airways produced strong antiviral proteins that stopped the virus in its tracks without having encountered it before.
Adults have a more adaptive immune system that is trained to recognise threats it has seen before – which is the principle behind vaccination.
But children have a stronger innate response that recognises dangers automatically, researchers said.
“The innate immune system of children is more flexible and better able to respond to new threats,” said Dr Masahiro Yoshida, one of the authors of the University College London study.
He described a very quick immune response in children that “helps to explain why they are less severely affected by Covid-19”.
Children can still spread the virus, and are recommended for vaccines in many countries. School-age children had the highest rates of infection in the UK in the week ending on December 17.
But rates of serious illness and death are very low – fewer than 100 people under 15 have died from Covid-19 in England. Scientists said this was not previously fully understood.
-
A man wearing a protective face shield and two mask waits be vaccinated in Quito, Ecuador. Elderly people waited hours to be inoculated. AP Photo -
An aerial view of cars queuing at a drive-in Covid-19 testing site in the car park of Hiram Bithorn baseball stadium, in San Juan, Puerto Rico. Reuters -
A shopper wearing a mask is reflected in a window as she walks down Oxford Street in London. Daily numbers of Covid-19 cases have passed 100,000 for the first time in the UK. AP Photo -
A nurse holds a vial of the Pfizer-BioNtech vaccine, in the Israeli town of Ramat Gan, near Tel Aviv. Israelis over the age of 60 and medical teams are being offered a fourth Covid shot. -
An official hands out Covid-19 testing kits in Bensonhurst, Brooklyn, in New York. The resumption of holiday travel and the emergence of Omicron has left Americans scrambling to find Covid tests. AFP -
Amelie and Ludo Khayat hold each other during a visit at the Covid-19 unit of Marseille University Hospital Timone, in Marseille, southern France. Ludo, 41, is recovering after spending 24 days in a coma. AP Photo -
Christmas shoppers brave the rain in Sydney's central business district. Covid-19 cases are rising in the Australian city and elsewhere in New South Wales, where health authorities have reported cases of the Omicron variant. Getty -
Travellers and vehicles crowd the departures and arrivals areas outside Tom Bradley International Terminal at Los Angeles International Airport during the holiday season. Reuters -
Medical workers prepare to conduct Covid-19 tests at a pop-up screening clinic in front of Seoul Station in South Korea. New coronavirus cases in the country have fallen to 7,000, but critical cases and deaths have surged to record highs of 1,083 and 109, respectively. EPA -
Car queue at a drive-through testing centre at Bondi Beach, in Sydney, Australia. New South Wales has broken another daily record for Covid-19 case numbers as Omicron takes hold, with hospital admissions almost doubling in a week. EPA -
A queue for Covid screening in Manhattan. Test provider CityMD closed 13 branches in New York temporarily because of staff shortages as demand surged. AFP -
Travellers queue outside the security checkpoint at Hartsfield-Jackson Atlanta International Airport in Georgia, US, as the Omicron variant spurs a rise in case numbers in many countries. Reuters -
Cars line up at a drive-through Covid-19 testing site at Tropical Park in Miami, Florida. As Covid-19 cases rise in the US, healthcare workers are urging people to take precautions during holiday get-togethers. AFP -
People wait in the check-in queue for Air France/KLM at Tom Bradley International Terminal at Los Angeles International Airport. EPA -
Christmas shoppers pictured out and about in Nottingham, England. The UK government has not imposed further restrictions in England to slow the spread of the Omicron variant. PA -
Pastor David Shrimpton, 57, known as the ‘flying padre’, puts on a face mask as he prepares to speak to pupils about Christmas at a school in Broken Hill, Australia. Since 2003, he has flown to some of Australia’s most isolated communities to preach. Reuters -
Medical workers treat a patient with Covid-19 in intensive care during the fifth wave of the pandemic in Neuchatel, Switzerland. EPA -
A protester wears a latex mask with syringes attached to it during a rally in front of the government headquarters in Bucharest, Romania. Marchers object to a Covid-19 ‘green certificate’ in workplaces to limit infections. AP -
Dr Sydney Sewall fills a syringe with a Covid-19 vaccine at a clinic in Augusta, Maine, US. AP -
A coronavirus test centre employee waits for clients on the shop-lined Kurfuerstendamm street in Berlin. Germany has announced new restrictions aimed at slowing the spread of the Omicron variant. AP -
A drive-through testing centre in Bellingham, Washington. The US state, which was hit hard early in the pandemic, has reported at least 400 cases of Omicron. AP -
New Yorkers check their Covid-19 results outside a rapid testing centre in Manhattan. AP -
People line up to be tested for Covid-19 in Washington, DC. Omicron variant is now the main coronavirus variant in the US. AFP -
Holiday travellers transit through Dulles International Airport in Virginia. United Airlines chief executive Scott Kirby has said the coming two weeks are expected to be its busiest since the pandemic began, despite Omicron. AFP -
Early closing for Oliver St John Gogarty, a pub in Temple Bar, Dublin. Under Irish coronavirus rules, which will last until January 30, hospitality venues must shut by 8pm. Getty -
People enjoy refreshments at a Christmas market in Piccadilly Gardens in Manchester. The UK government has faced pressure to tighten coronavirus restrictions. AFP -
A Ferris wheel in the historic centre of Antwerp, Belgium. The government will meet to decide whether new Covid-19 measures will be taken. AP -
A child watches a Covid-19 test being administered in Washington, DC. EPA -
A poster featuring Father Christmas and Wee Jimmy Krankie, a popular character from children’s TV, on Leith Walk, Edinburgh. The Scottish government is considering whether to tighten Covid restrictions. PA -
A man receives his Covid-19 vaccine inside a National Health Service bus in the town of Farnworth, near Manchester in north-west England. AFP -
A trader works on the floor of the New York Stock Exchange at the start of trading on Monday after Friday’s steep decline in global stocks amid fears about the Omicron variant. Stocks fell sharply in morning trading, with the Dow falling more than 500 points. Getty -
People arrive to receive a booster dose of Covid-19 vaccine at an inoculation centre in Kuwait City. EPA -
People crowd together without social distancing at a railway station in Bangalore, India. EPA -
Women wear masks in Tehran. The Iranian Health Ministry said it had found a case of the Omicron variant in the country. EPA -
People wait to receive a dose of the Pfizer-BioNTech Covid-19 vaccine in Bangkok, Thailand. Bloomberg -
Churchgoers wearing masks observe social distancing as they attend a pre-dawn Mass at a church in Paranaque, Metro Manila, Philippines. Getty -
An intubated Covid-19 patient receives treatment in the intensive care unit of Westerstede Clinical Centre in north-west Germany. AP
The UCL study explained that the airway proteins, known as interferons, give a signal to nearby cells to tighten their defences against an intruding virus.
Adults produce them too, but they were found to be stronger, more numerous and generated more quickly in children.
Interferons have been studied as a possible therapy for Covid-19, while researchers say a nasal swab could be used to measure the immune response in adults.
The findings are based on blood samples from 78 people, including children and adults infected by the virus.
This produced a data set of more than 650,000 individual cells that revealed dozens of cell types in the airways and blood – including some never previously described.
In addition, children were less prone to a dangerous effect in which the immune system works against the body by attacking infected cells. This is known as a cytotoxic response.
“Once the virus has spread to several areas of the body, organ damage can be caused by the immune system trying and failing to control the infection,” said Dr Marko Nikolic, another UCL study author.
“Our study shows that not only do children respond better initially, if the virus does enter the blood the cytotoxic response is less forceful.”
The research from UCL, the Wellcome Sanger Institute and their collaborators is published in Nature.
