Delta SARS-CoV-2 variant does not make children sicker than Alpha, study finds
Children are not at risk for more severe COVID-19 disease with Delta compared to earlier variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), according to a new medRxiv* pre-print study. In the first large-scale epidemiological study comparing SARS-CoV-2 infection between variants in children, researchers found that children were more likely to be as sick with Delta as if they were infected with the Alpha variant.
In May 2021, the Delta variant overtook Alpha as the predominant strain of SARS-CoV-2 in the UK. Later in the summer, the United States experienced cases of the coronavirus in both vaccinated and unvaccinated individuals due to the Delta variant.
New data suggests that most children have exhibited symptoms of COVID-19 for less than two days and short durations of illness. Only a few children had to be hospitalized.
The study can help find out whether children are in urgent need of immunization. “Our study adds quantitative information on the manifestation of Delta variant infection in children, which will contribute to the ongoing debate regarding the role of vaccination in children, especially for young children,” concluded the research team.
How they did
Emma L. Duncan of King’s College London in the UK and her team compared the severity of symptomatic COVID-19 infections in children aged 5 to 17. The study took place between December 28, 2020 (when Alpha was dominant) and July 8. 2021 (when Delta was dominant).
The researchers assessed the differences in symptoms, the duration of the symptoms, and the severity of the symptoms. They also measured how many children had to be hospitalized and how many remained infected after 28 days.
Overall, there were 276 children aged 5 to 11 and 418 children aged 12 to 17 infected with the Alpha variant.
Likewise, 227 children between 5 and 11 years old and 479 children between 12 and 17 years old were infected with the Delta variant.
Children tended to recover from COVID-19 symptoms within a week, regardless of the variant
Disease profiles were similar between children infected with Alpha or Delta.
With either variant, most children recovered in less than a week (median of 5 days). Depending on age, younger children (5-11 years) tended to recover after 4 days, and older children managed to recover after 6 days.
Overall, 5 younger children and 22 older children took more than 28 days to recover from the COVID-19 disease. No new symptoms appeared in the children who had a more prolonged infection.
Prevalence of symptoms reported during illness (up to 28 days) in younger (5 to 11 years old) and older children (12 to 17 years old) with COVID-19 during periods of predominance of Alpha or variant variants SARS-CoV-2 delta.
Young children infected with Alpha developed blisters that lasted longer than other symptoms of COVID-19. However, the chances of developing blisters were extremely low, around 1%.
Similar symptom profiles between SARS-CoV-2 strains
Young children have reported similar symptoms with either variant, including a runny nose, headache, and fatigue.
Older children infected with Alpha were more likely to have headaches, fatigue and a runny nose. In contrast, older children infected with Delta reported more headaches, sore throats, and fatigue.
Seven COVID-19 symptoms were shared between the two variants – headache, fatigue, fever, loss of smell and / or taste, sneezing, runny nose and sore throat.
Symptoms more common with Delta than with Alpha included fever, dizziness, “chills or chills”, eye pain, and a hoarse voice.
Median duration and IQR of each symptom reported during illness in younger (5-11 years) and older (12-17 years) children with COVID-19, whose illness lasted
Few children required hospitalization for severe COVID-19 infection
Only a few children had to be hospitalized with one or the other variant.
About 2.2% of younger children and 1.9% of older children infected with Alpha presented to the hospital.
In the Delta group, 3.5% of young children and 1.7% of older children were hospitalized.
Limitations of the study
The research team notes that school disruptions due to the lockdown may have affected the exposure rates of schools and school buses. Additionally, their data may have been affected by the lifting of the UK’s national lockdown on March 29, 2021.
The end of the lockdown changed the prevalence of SARS-CoV-2 and other respiratory viruses, with an increase in influenza rather than SARS-CoV-2 being reported at the start of the school year. Seasonal differences can also influence the circulation of respiratory viruses such as seasonal allergic rhinitis which can have similar symptoms.
Therefore, the lack of simultaneous testing suggests a possibility of coinfection with other respiratory viruses.
medRxiv publishes preliminary scientific reports which are not peer reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.