The risk of severe illness and death from COVID-19 is extremely low in children and teenagers, according to the most comprehensive analyses of public health data yet.
However, research by UCL, University of Bristol, University of York and the University of Liverpool reveals that having COVID-19 increases the likelihood of serious illness in the most vulnerable young people as well as those with pre-existing medical conditions and severe disabilities. The risks remain low overall, say the researchers.
They found children and young people with Black ethnicity had a greater risk of being admitted to intensive care compared to white and that young people with multiple conditions had the highest risk of needing ICU care.
The findings are published in three new pre-print studies and will be submitted to the UK’s Joint Committee on Vaccination and Immunisation (JCVI), the Department for Health and Social Care (DHSC)and the World Health Organisation (WHO).
It is hoped their findings will inform vaccine and shielding policy for the under-18s. None of the papers examined the impact of long COVID.
One preprint study, published on medRxiv, found that 251 young people aged under 18 in England were admitted to intensive care with COVID-19 in the first year of the pandemic, up until February 28, 2021.
This equated to young people of that age group having a one in about 50,000 chance of being admitted to intensive care with COVID-19 during that time.
When they looked at PIMS-TS, a rare inflammatory syndrome in children caused by COVID-19, they found 309 young people were admitted to intensive care, equating to an absolute risk of one in 38,911.
A linked preprint study, published on ResearchSquare, looked at data for England and found that 25 children and young people had died from COVID-19, which equates to an absolute risk of death from COVID-19 of approximately two in a million.
Professor Russell Viner, from UCL Great Ormond Street Institute of Child Health and senior author on two of the studies, said: “These new studies show that the risks of severe illness or death from SARS-CoV-2 are extremely low in children and young people.
“Those young people at higher risk are those who are also at higher risk from any winter virus or other illness – that is, young people with multiple health conditions and complex disabilities.
“COVID-19 does however increase the risks for people in these groups to a higher degree than for illnesses such as influenza.
“Our new findings are important as they will inform shielding guidance for young people as well as decisions about the vaccination of teenagers and children, not just in the UK but internationally.”
Lead author Dr Joseph Ward, also from UCL Great Ormond Street Institute of Child Health, said: “The study found a higher risk of admission to intensive care among young people of Black ethnicity compared to white, as well as among young people with health conditions such as diabetes, asthma and cardiovascular disease. Young people with multiple conditions had the highest risk.
“These conditions were also risk factors for other illnesses leading to admission to intensive care, but to a lesser degree than for COVID-19.”
Dr Rachel Harwood, from the University of Liverpool, who was lead author of the third pre-print study, said their meta-analysis found similar risk factors to the other studies, but also found that obesity increased the risk of severe COVID-19 illness.
Lead author Dr Clare Smith, from the University of Bristol, said 40% of children and young people who had a positive COVID-19 test at the time of death actually died from COVID-19. Children and young people with complex neurodisability were at the highest risk of death.
Senior author Professor Lorna Fraser (University of York) said: “It’s important to remember that the risks are very low for all children and young people. Even when we found higher risks for some groups with severe medical problems, these risks were still very small compared to risks seen in adults.”
Dr Elizabeth Whittaker (Imperial College London) said: “It is reassuring that these findings reflect our clinical experience in hospital = we see very few seriously unwell children. Although this data covers up to February 2021, this hasn’t changed recently with the Delta variant. We hope this data will be reassuring for children and young people and their families.”
Meanwhile, writing for The BMJ, the paediatrician who led the vaccine development in the UK, Professor Andrew Pollard, argues against mass vaccination of children rather than to those who are most clinical vulnerable.
Professor Pollard says it is not clear the benefits outweigh the risks = while vaccines are still in short supply and should be directed to those who need them most.
Methotrexate weakens vaccine response
Meanwhile, a new study presented at this year’s European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) and published in The Lancet Rheumatology, shows that the antibody, but not the T-cell, response to the first dose of the Pfizer COVID-19 vaccine is weakened in people who are prescribed methotrexate.
However, antibody and T-cell responses are preserved in patients taking biological drugs such as tumour necrosis factor (TNF) inhibitors.
Dr Satveer Mahil, Professor Catherine Smith and colleagues at St John’s Institute of Dermatology, Guy’s and St Thomas’ NHS Foundation Trust, London, UK and King’s College London, enrolled 101 participants from January 14, 2021, to April 4, 2021.
Of these, 84 had psoriasis and the remaining 17 were healthy volunteers. The participants’ median age was 43, 55% were male, 84% were white and none had had COVID-19 previously.
The psoriasis patients were taking a range of treatments: 17 took methotrexate, with a median dose of 15 mg/week; 27 took TNF inhibitors; 15 took interleukin (IL)-17 inhibitors; and 25 were prescribed IL-23 inhibitors.
Each had their immune responses were measured immediately before being given a single dose of the Pfizer vaccine and 28 days later.
The researchers found rates of seroconversion were lower in the patients on immunosuppressants. All 17 healthy volunteers had evidence of seroconversion, compared with 78% of those on immunosuppressants.
The lowest seroconversion rate was 47% in patients taking methotrexate.
Levels of neutralising antibodies were significantly lower in patients taking methotrexate compared to healthy controls but were preserved in those taking biologics.
T-cell responses were detected in all groups at similar rates and levels, and many participants without evidence of seroconversion showed a T-cell response.
Levels of neutralising antibodies to the B.1.1.7 (Alpha) variant were also tested and these were low in all participants, including healthy volunteers, which, say the authors, underlies the need to continue taking preventative measures after having a first dose of the vaccine.
Researchers will examine data on the participants’ response to the second dose.
Ward JL, Harwood R, Smith C et al. Risk factors for intensive care admission and death amongst children and young people admitted to hospital with COVID-19 and PIMS-TS in England during the first pandemic year.
Smith C, Dodd D, Harwood R, Ward J et al. Deaths in Children and Young People in England following SARS-CoV-2 infection during the first pandemic year: a national study using linked mandatory child death reporting data.
Harwood R, Yan H, Talawila de Camara N et al. Which children and young people are at higher risk of severe disease and death after SARS-CoV-2 infection: a systematic review and individual patient meta-analysis.
Mahil SK, Bechman K, Raharja A et al. The effect of methotrexate and targeted immunosuppression on humoral and cellular immune responses to the COVID-19 vaccine BNT162b2: a cohort study. Lancet Rheumatology 9 July 2021
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