Are children and young people more susceptible to the newer strains of SARS-CoV-2 than earlier ones? Current evidences

INTRODUCTION

According to the Centres for Disease Control and Prevention (CDC), it has been reported that children are less susceptible to develop severe manifestations of COVID-19; however, they can be infected with the virus, get sick from COVID-19, and spread the virus to others.¹ The majority of the children infected with COVID-19 have been reported to have mild or no symptoms.¹ However, with the emergence of new variants of SARS-CoV-2 particularly the B.1.1.7 variant, concerns have been raised regarding the susceptibility of the infection from these new variants among the paediatric population.

CURRENT EVIDENCE

According to the CDC, there are currently five variants of concerns (VOCs) in the United States, including B.1.1.7 (UK variant), B.1.351 (South African variant), P.1 (initially detected in Brazil), and B.1.427 and B.1.429 (both of which were first identified in California, US).² Studies have also shown that these variants, including 501Y.V1 (B.1.1.7) in UK, P.1 (501Y.V3) in Brazil, and 501Y.V2 (B.1.351) in South Africa, contribute to increased transmission of COVID-19.

According to the report by Davies et al the UK variant has been estimated to be more transmissible than the precursor lineage but has no clear evidence for a change in disease severity; however, the greater transmission will lead to higher incidence and more hospital admissions.³

The clinical impact of the new SARS-CoV-2 lineage B.1.1.7 on children and young adults (under the age of 18 years) with acute respiratory COVID-19 is yet to be determined. Also, it has been hypothesized in the few reports that the paediatric population might be more susceptible to infections with VOCs as compared to the original strains of SARS-CoV-2; however, till date, no such evidence has come up. Media reports of increases in hospital admissions and more serious illnesses in children and young people have caused public chaos and panic, and the latest variants, especially the B.1.1.7 variant, have been implicated in causing a more pathogenic infection in this population.

However, recent data show that B.1.1.7 has not changed the paediatric hospitalization rate and that severe COVID-19 remains rare among the kids. No significant differences were found with respect to age, the proportion of patients with comorbidities, the proportion of patients from Black, Asian, and minority ethnic background, or deprivation score between the groups representing first and second waves.⁴ There was also no evidence of more severe disease in children and adolescents during the second wave of COVID-19, implying that the infection with the B.1.1.7 variant might have a similar clinical course to the infection with the original strains.⁴

DISCUSSION

The novel SARS-CoV-2, which causes the disease called COVID-19, spread rapidly across the globe causing major devastations in life and economy of the countries. A striking and consistent observation across all the countries affected by the COVID-19 pandemic was the difference in severity of COVID-19 in different ages: severity, the need for hospitalization and mortality rise steeply with older age while severe disease and deaths were relatively rare in children and young adults.^5-7 Most children infected with SARS-CoV-2 are asymptomatic or have mild symptoms, most commonly fever, cough, pharyngitis, gastrointestinal symptoms and changes in sense of smell or taste.^8,9

Whether children are also less often infected by SARS-CoV-2 is an ongoing debate. Large epidemiological studies suggest that children comprise only 1 to 2% of all SARS-CoV-2 cases.^10-12 However, these numbers heavily depend on testing criteria and, in many reports, testing was done only in individuals who were symptomatic or required hospitalization, which is less often the case for children. Some studies suggest that children are just as likely as adults to become infected with SARS-CoV-2.¹³ However, many recent studies report that children are less likely to get infected after coming in contact with a SARS-CoV-2-positive individual.^14-18

It has been proposed that children and adolescents have similar viral loads as of adults and may therefore be as likely to transmit the infection of SARS-CoV-2 as adults.^19-22 In addition, some studies suggest that the viral load in asymptomatic and symptomatic individuals infected with SARS-CoV-2 is similar.^23-25 However, assuringly, transmission in schools from children either to other children or to adults has been quite rare.^26-28

The observation that children and adolescents are less frequently infected with SARS-CoV-2 and that they have less severe symptoms compared to adults is similar to that reported for SARS-CoV-1 and Middle east respiratory syndrome (MERS)-CoV.^29-31 However, this pattern is strikingly different to that for infection with most of the other respiratory viruses [e.g., respiratory syncytial virus (RSV), metapneumovirus, parainfluenza or influenza viruses], for which the prevalence and severity are both higher in children.³²

Emergence of newer strains/variants of COVID-19 such as B.1.1.7, during the second and third waves in many countries have resulted in the hypothesis that the children and adolescents, the age-group which was least susceptible to the classical or original strains of SARS-CoV-2 would be most affected and the new variants may be more severe in this age-group compared to adults. However, few studies conducted among those infected with newer variants such as B.1.1.7 have found that children and adolescents still remain the least affected age-group and mortality, which is quite rare and only in those children who have co-morbidities like cancer or type 1 diabetes, in them due to the newer strains is found comparable to the earlier or original strains of the virus.

CONCLUSION

No evidence of more severe disease has been found in children and young people during the second and/or third wave of COVID-19 pandemic, suggesting that infection with the newer variants of SARS-CoV-2 does not result in an appreciably different clinical course to the original or earlier strains. Severe acute respiratory COVID-19 still remains an uncommon occurrence in children and young people.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

REFERENCES

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