SARS-Cov-2 Infection in Children

By Dr Tan Poh Tin | 26 June 2020

Are children less often infected by Covid-19? They show milder disease, have less hospitalisation, and deaths are rare.

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A mum told me she was anxious about sending her child back to school. “I really don’t know how to help her with school work at home, but is it really safe?” Here are some of the points I shared with her.

This article is not meant to be taken as blanket medical advice, merely an opinion based on publications which lag behind evolving Covid-19 data. (Best practice guidelines may change, even U-Turn!) Do consult your family doctor who knows your child’s health condition, and especially, where there are elderly family members at significant risk at home.

Children (<19 years) only 1%-5% of all confirmed Covid-19 cases worldwide

Globally, about 29.3% of the world is under 18 years of age (7.9% above 65 years). In most studies, confirmed Covid-19 among children below 19 years (henceforth referred to as “children” or “child”) only makes up 1-5% of all cases.

Could it be that children, for mechanisms which remain unknown, are significantly less likely to be infected than adults? Is their infection often so mild, that they may not have been brought for medical attention or testing and hence not counted?

51% of the largest study of 2,143 paediatric patients with Covid-19 from China were reported to have mild symptoms (fever, fatigue, myalgia, cough), 4% were asymptomatic.

There have been multiple reports of children with asymptomatic SARS-CoV-2 infection, up to 13% in one study. What is the role of such undiagnosed child cases in Covid-19 transmission?

The researchers in this (pre-print, non-peer reviewed) article, COVID-19 Infection in Children: Estimating Paediatric Morbidity and Mortality, searched 23 government websites of the 70 countries with a minimum 1,000 Covid-19 cases by 13 April 2020. Of 424,978 cases in these 23 countries, 8,113 (1.9%) were children. They also reviewed nine publications with 4,251 cases in four additional countries.

Combining data from the websites and publications, 14% required admission and 7% of the admitted children needed ICU. There were only 15 reported child Covid19 deaths in this large series.

Malaysia, to date, has 317 Covid-19 positive children (3.7% of total 8,572 cases) with no deaths. None were ventilated and a few needed oxygen via nasal prong. (Source: verbal communication).

Most Covid-19 children present with mild symptoms and require supportive care only. Prognosis is typically good. They recover within one to two weeks.

This systematic review of 18 studies (1 December 2019 to 3 March 2020) had 1065 cases (<19 years of age) and only one death. All articles reflected research in China, except for a Singapore case report of a well infant with Covid-19 with high viral load.

Most presented with mild respiratory symptoms, fever, dry cough and fatigue or were asymptomatic. Bronchial thickening and ground-glass opacities on chest X-ray were the main radiologic features. These X-ray findings were also reported in some asymptomatic patients.

Most paediatric patients were hospitalised. Symptomatic children received mainly supportive care. A 13-month-old presented with pneumonia, complicated by shock and kidney failure, and was successfully treated with intensive care.

No deaths were reported in the age range of 0 to 9 years. One death was reported in the age range of 10 to 19 years.

Deaths have been uncommon in children with Covid-19 in most countries

A systematic literature review of 45 published papers and letters showed that only 1%‐5% of all confirmed Covid‐19 cases (1 Jan – 18 March) were children (0-19 years).

The China CDC Novel Coronavirus Pneumonia Emergency Response Epidemiology Team analysed 72,314 Covid-19 cases reported through to 11 February 2020. 44,672 were positive by RT-PCR. Of these confirmed cases, only 2% were children aged 0-19 years. Only 0.9% (416 cases) were below 10 years of age with no death. There was one death in 10-19 year group (549 cases). 86.6% cases were 30–79 years old. Those older than 60 years were 31.2% of total cases, but contributed to 81% of deaths.

1.2% of 22,512 Italian Covid-19 cases were children (0-18 years) with no deaths as of March 15, 2020. In fact, no deaths were reported below the age of 30 years in this report. 87.9% Italian deaths were aged above 70 years, who made up 37.6% of total cases.

In the United States, as of April 2, 2020, there have been three deaths among children. As of April 2, 2020, infants aged <1 year accounted for 15% of paediatric Covid-19 cases in the U.S. Compared to adult patients, there were fewer children with Covid-19 requiring hospitalisation (6–20%) and ICU admission (0.6–2%).

However, this age group remains underrepresented among Covid-19 cases in patients of all ages (0.3%) compared to their percentage in the U.S. population (1.2%).

In the United States, of 4,226 Covid‐19 cases detected 12 Feb -16 March, only 5% were children. Less than 1% of all Covid-19 hospitalizations were children. Overall, adults aged >65 years account for 31% of cases, 45% of hospitalizations, 53% of ICU admissions and 80% of deaths associated with Covid-19. The highest percentage of severe outcomes was among persons aged ≥85 years.

In Germany, the Robert Koch Institute reported 174,355 Covid-19 cases as of 17 May 2020. Infected children <10 years was 1.9% and 10-19 years was 4.3%. Only three deaths occurred among those 3-18 years, all of whom had underlying conditions.

Widespread community testing found significantly less infected children

The reports from most countries seem to suggest that children are underrepresented among cases, especially the severe and fatal ones. Is this because they are less likely to be infected even when exposed (and why)? Or are there more asymptomatic cases who are missed because they do not get tested or screened? Have there been clusters from these asymptomatic, undiagnosed infected children?

In a Japanese report, the age-specific attack rates for 313 domestically acquired Covid-19 cases were 7.2% for male and 3.8% female children 0-19 years, compared to 22.2% male, 21.9% female aged 50-59 years.

In Italy, following the first Covid-19 death in the Municipality of Vo, researchers (RT-PCR) tested 85.9% and 71.5% of its 3275 population at the beginning and end of the two week lockdown. 2.6% adults were positive in the first screen and 1.2% two weeks later. Notably, 43.2% of the confirmed cases detected across the two surveys were asymptomatic. None of the 234 children in Vo, aged below ten years, tested positive. 13 children, living with infected family members, also tested negative (i.e. did not get infected).

A population-based study in Iceland (364,000 inhabitants), using targeted screening and by invitation, showed that children under 10 years of age and females had a lower prevalence of SARS-CoV-2 infection than adolescents or adults and males.

Nasopharyngeal and oropharyngeal samples were combined into a single tube for each participant before RNA isolation. Targeted testing involved 9,199 persons at high risk for infection (mainly those who were symptomatic, had recently travelled to high-risk countries, or had contact with infected persons). Open invitations were extended to 10,797 persons and random invitations sent to 2283 persons. This survey covered 6.1% of the Icelandic population.

In the targeted group, 6.7% of the 564 children under the age of 10 years tested positive, in contrast to 13.7% positive aged 10 years and older. In the population-screening group, the difference was even more marked. None of the 848 children under the age of 10 years tested positive, as compared with 100 (0.8%) of 12,232 persons 10 years of age or older.

At the current time, children do not appear to be super spreaders

An Englishman infected from Singapore stayed 4 days in the French Alps chalet with 10 English tourists and a family of 5 French residents. He infected 5 individuals in France, 5 in England and 1 in Spain. One infected 9-year-old child visited 3 different schools while symptomatic. Not a single SARS-CoV-2 case was found among the child’s 172 contacts.

In a school study from New South Wales, Australia, a proportion of 863 close contacts of 18 Covid-19 cases (9 child, 9 teachers) from 15 schools were either tested by RT-PCR or had blood tested for antibodies (positive antibody test taken as a marker of recent infection). No evidence of children infecting teachers was found.

735 students and 128 staff were close contacts of these initial 18 cases. One child from a primary school (positive nasal swab and antibodies) and one child from a high school (positive antibodies) may have contracted Covid-19 from the initial cases at their schools. No teacher or staff member contracted Covid-19 from any of the initial school cases. (In this report, a ‘close contact’ is defined as a person who has been in face-to-face contact for at least 15 minutes or in the same room for two hours with a case while infectious).

The authors concluded: “It is notable that half of the initial cases that occurred in schools were in staff. This is consistent with the higher rate of Covid-19 seen in adults than in children. This reinforces the need for both adults and children to ensure they do not attend school when ill and if they become ill to promptly isolate themselves and seek medical attention. It is also important for all adults, including teachers, to follow recommended social distancing practices while at school and in the community.”

Children are less likely to be index case (case#0) in household clusters

A literature review of 31 household transmission clusters from China, Singapore, South Korea, Japan, and Iran showed that only 9.7% started from a child index case. Data from Guangzhou have supported this, finding an even lower rate of children as index cases in households at 5%.

The majority of children infected by SARS-CoV-2 have been part of a family cluster outbreak. In contrast, adults more often get infected outside the household and spread to children at home.

Take-Home Points

  • Covid-19 infection in children occur less commonly and are milder than adults requiring less hospitalisation and intensive care.
  • Infants below 12 months and children with underlying conditions, e.g. chronic lung disease (including asthma), cardiovascular disease, and immunosuppression may be at higher risk of infection, severe disease, hospitalisation and intensive care.
  • Covid-19 deaths in children are uncommon.
  • An increase in Kawasaki syndrome cases (multisystem inflammatory syndrome in children (MIS-C) linked to Covid-19 have been reported, and more information will no doubt be available in due course. In my paediatric practice in Kuching, pre-Covid, I have referred one to two cases a year for investigation and hospitalization. So far, I have not seen any increase in cases.
  • Transmission risks from an infected child to others in the home or school seem to be lower than from adults.
  • Infected adults seem more likely to transmit the virus to children than the other way around.
  • Talk to your doctor when child is unwell – he may prefer you to go directly to the Covid screening centres rather than to clinic.
  • Wear masks, hand-wash frequently, help school sanitise common areas, toilets and high touch items, keep classrooms and dormitories well ventilated (open windows),
  • Schools with dormitories should be particularly vigilant when their students, teachers or supportive staff are not well. These are potential super-spreader hotspots.

So far no children have died in Malaysia from SARS-Cov-2. Let’s keep it that way by maintaining a high index of suspicion, testing and isolating when in doubt. Early diagnosis and admission can prevent deterioration and death. Malaysia Boleh.

A fusion opinion from a Sarawakian public health specialist, paediatrician, ex-associate professor, disaster relief and medical volunteer, passionate about helping people learn.

  • This is the personal opinion of the writer or publication and does not necessarily represent the views of CodeBlue.
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