What We Know About the Impact of Covid-19 on Children
Education workers wearing protective masks and face shields greet students in Toronto. (Photographer: Cole Burston/Bloomberg)

What We Know About the Impact of Covid-19 on Children

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Young children typically are “superspreaders” of respiratory germs, so it’s puzzling that they don’t seem to be major transmitters of the coronavirus that causes Covid-19. They’re also relatively absent among hospitalized patients. Initially, that was thought to be because they’re less likely to become seriously ill if infected. Later studies indicate that those of primary school age, at least, may be less likely to catch the virus in the first place. Still, they’re not immune to an array of indirect Covid-19 harms, including physical abuse, learning gaps, anxiety and depression stemming from school closures, social isolation and other stress-inducing consequences of the pandemic. That’s informing considerations for how to safely keep kids in school.

1. How likely are kids to get Covid?

Of all Covid-19 cases reported worldwide last year, children under 18 years accounted for about 8%, despite comprising 29% of the global population, according to the World Health Organization. Under-reporting of pediatric infections is likely. Compared to adults, children with Covid-19 are more likely to have no symptoms or, if they do, predominantly mild ones limited to the nose, throat and upper airway. They rarely require hospitalization.

2. Why might kids be less susceptible?

There are multiple reasons. Children may have a stronger innate immune response to the virus, deploying nonspecific defense mechanisms within hours of its appearance in the body. Past infections caused by coronaviruses that cause the common cold may enable the B cells (a type of immune cell) in children to make antibodies that cross-react with SARS-CoV-2 -- an advantage most adults lack. Importantly, children may lack many of the factors thought to put adults, particularly the elderly, at risk of more serious illness from Covid-19, such as:

  • damage to the lining of blood vessels that occurs with age and increases the susceptibility to the formation of dangerous clots;
  • an abundance of the type of cell-surface protein that the coronavirus uses to invade cells and cause an infection;
  • age-related changes in the immune system that hinder viral clearance;
  • chronic conditions such as obesity, diabetes and hypertension as well as chronic lung, heart or kidney disease.

3. Can kids still become seriously ill?

Yes. Death is extremely rare in children with a SARS-CoV-2 infection, although it can occur in those who are already very sick with cancer or other life-threatening conditions. Relatively more common is a serious blood disorder, known as pediatric inflammatory multisystem syndrome (PIMS) or multisystem inflammatory syndrome in children (MIS-C), which has affected more than 2,000 children in the U.S. alone. This potentially lethal condition is similar to Kawasaki disease and occurs at a rate of about 2 per 100,000 people younger than 21 years -- a tiny fraction of the 322 per 100,000 in which coronavirus infection is diagnosed in that age group. Although the condition is easily treated, some patients may suffer heart abnormalities of varying significance.

4. Anything else?

It’s possible some children may suffer post-acute or “long Covid” symptoms much like the fatigue, muscle and joint pain, breathing difficulties and heart palpitations reported in adults. Data are lacking though. A small study from Rome found half of pediatric patients enrolled had at least one persisting symptom after 120 days, with 43% suffering from an ailment that interfered with daily activities. The research, which was released Jan. 26 ahead of peer-review and publication, was based on a survey of the caregivers of 129 Covid-19 patients ages 18 years and younger. An even smaller study in September found heart damage in 1 in 7 college sports competitors, including in those whose coronavirus infection caused no obvious symptoms.

5. Do kids spread the virus?

Yes. They are capable of transmitting SARS-CoV-2 to other children and to adults. However, studies have found that younger children in particular don’t tend to be the main drivers of transmission within households and communities. In the U.S., resurgent Covid-19 epidemics in 2020 were driven by adults ages 20-49. Even after schools reopened in October, that age group accounted for almost three-quarters of SARS-CoV-2 infections, whereas less than 5% originated from children ages 0-9 and less than 10% from those ages 10-19, a study published in the journal Science found. Children under 10 also may be less susceptible to infection. That’s reflected in the higher frequency of outbreaks reported in secondary and high schools compared with primary or elementary schools and daycare centers, in places where they have remained open.

6. Do the new variants change anything?

It’s unclear. The B.1.1.7 variant discovered in the U.K. in September is significantly more transmissible than previously circulating strains, and has been associated with an uptick in spread across all age groups, including children under 15. The age distribution of Covid-19 cases may change as vaccination programs prioritizing older people are rolled out. Israel, where the variant has proliferated since December, reported a steep jump in SARS-CoV-2 infections among young people in January, threatening to prolong school closures. All individuals aged 16 years or older became eligible to receive the vaccine on Feb. 4. The previous month, more than 50,000 children and teens tested positive the previous month -- more than the nation recorded in any month during its first and second waves -- with the proportion of new daily cases among kids under 10 increasing by 23%, the BMJ medical journal reported Feb. 8.

7. How risky are schools?

The U.S. Centers for Disease Control and Prevention said in February that available data show “in-person learning in schools has not been associated with substantial community transmission.” However, a review in December by its European counterpart found SARS-CoV-2 can spread within schools, and clusters of Covid-19 cases have been reported in preschools, primary and secondary schools. The frequency of cases appears to reflect levels of community transmission; when it’s low and when appropriate mitigation measures are applied, schools aren’t likely to be the main drivers of Covid-19, according to the WHO. Staff and other adults spending prolonged periods in schools don’t appear to have a higher risk of Covid-19 than other occupations.

8. Why close schools?

Health officials say such a decision shouldn’t be taken lightly due to the negative impact school closures have on education and the physical and mental health of children, but rather as a last resort. Although keeping kids out of classrooms can help reduce transmission, that alone won’t prevent Covid-19 cases in the community in the absence of other measures, such as restrictions on gatherings and mandatory mask-wearing.

9. How has the pandemic affected learning?

The disruption has been unprecedented, affecting more than 1.6 billion learners in over 190 countries in 2020 alone, according to Unesco. The majority of students continued to be affected by full or partial closures of schools and universities into January, increasing the risk of learning loss, dropping out of education and social isolation. Although alternatives to in-person learning have been introduced, some 470 million pupils can’t get access to online or other required content for remote education.

10. What effect will that have?

Prolonged school closures look certain to result in long-lasting economic and psychological harm, with deprived and marginalized groups affected most. The longer disadvantaged children are out of school, the less likely they are to return. According to Unicef, kids from the poorest households are almost five times more likely to be out of primary school than those from the richest. Although children in low- and middle-income countries will be hardest hit, large inequities exist in wealthy countries too. Estimates indicate that 3-10% of students in the U.S. have been “disengaged for almost the better part of a year,” according to Annette C. Anderson, deputy director of the Center for Safe and Healthy Schools at Johns Hopkins University in Baltimore. Learning loss will probably be greatest among youth from low-income families, and Black and Hispanic students, exacerbating existing achievement gaps by 15-20%, McKinsey & Co. estimated in June. The consulting firm predicted U.S. students in grades K-12 may lose, on average, the equivalent of a year of full-time work in lifetime earnings solely as a result of Covid-related learning losses. Black and Hispanic Americans would suffer the highest toll. That’s supported by modeling by researchers at the University of Washington and University of California, Los Angeles who found, by not graduating high school, children may experience a lifetime of lower wages and disadvantage, and that prolonged, missed instruction may reduce life expectancy.

What We Know About the Impact of Covid-19 on Children

11. Why are schools so important?

Beside being a place of learning, schools often provide safe places, as well as social, emotional and nutritional support. Dropping out of school or missing lessons increases the risk of teenage pregnancy, sexual exploitation, child marriage, violence and food insecurity, according to Unicef. Prolonged school closures may also disrupt important services, such as immunization and psychosocial support.

12. Are there measures that can mitigate risk for schools?

Yes. The CDC has outlined strategies that include the proper use of masks, social distancing, strict cleaning and maintenance of classrooms and rapid contact tracing, echoing guidelines and recommendations from the WHO and others. These also include guidance on producing outbreak prevention and management plans, testing for cases, ensuring adequate ventilation and hygiene practices and frequent communication with parents, students, teachers and staff. U.S. President Joe Biden acknowledged that many of the CDC guidelines would be costly and difficult to implement, but called reopening schools a “national imperative.” Vaccination will help too. Studies are underway to test the efficacy of immunizations in children and adolescents. Pfizer said in late March that shot was 100% effective in a final-stage trial in kids ages 12 to 15, a finding that could pave the way for teens and pre-teens to get shots before the next school year.

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