SARS-CoV-2 Infections Among Children and Adolescents With Acute Infections in the Ruhr Region

The incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the population in the Ruhr area rose sharply starting in October 2020. Little is known regarding the SARS-CoV-2 infection rates in children and adolescents with acute infections, the viral load of a SARS-CoV-2 infection in different age groups, or the importance of known contacts with infected people within and outside the family.

Methods

Data from an ongoing study from Bochum and Herne of symptomatic children in outpatient care who were very young (0–3-year-olds [yo]), pre-school–aged (4–6 yo), primary school–aged (7–11 yo), or adolescents (12–17 yo). In the period from April 2020 to March 2021, these children presented on an outpatient basis to pediatric practices or pediatric emergency services due to acute symptoms of infection. All received a SARS-CoV-2-PCR test (PCR, polymerase chain reaction). The viral load was estimated using the cycle threshold (CT) value (≤18: high viral load; 19–29: medium viral load; ≥30: low viral load). Known contacts to a SARS-CoV-2–infected person, the duration of the illness, any activities of the parents in high-risk professions (medicine, catering, public transport), and vaccination status were recorded. Mutation analyses of the virus strains were not available.

Results

Comparing the data of infected persons recorded by the Robert Koch Institute (RKI) (with or without symptoms, over the same period and in the same region and same age groups) with the 5710 symptomatic children/adolescents in our study revealed that our cohort comprised a disproportionately high number of 0–3 yo with a positive PCR test (36% versus 14%), but fewer 12–17 yo (23% versus 52%). The course of the infection over time, however, was comparable. The proportion of positive SARS-CoV-2 PCR tests (n = 267; 4.7%) rose from 0.3–0.9% in the 2nd and 3rd quarter of 2020 (one positive test per 355 negative tests), to values of 7–8.6% in the 4th quarter of 2020 (1:12). At the beginning of 2021, the number of acute infections, and in parallel the test frequency, fell significantly in all age groups (Table). The proportions of positive tests remained almost the same in the respective age group. The infection rate of 12–17 yo (7.1% of all tests; odds ratio [OR], 1.85; 95% confidence interval [CI] [1.43, 2.41]) was almost twice as high as that of the other children (7–11 yo, 4%; 4–6 yo, 3.5%; and 0–3 yo, 4.6%). Comparing the number of infections in 3rd quarter of 2020 with those in January 2021 revealed a 72% and 85% decrease for the 7–11 yo and the 12–17 yo groups, respectively, but only a 53% decrease for the 4–6 yo group; the numbers for all age groups rose again from March 2021 to the levels observed at the end of 2020. In particular, higher virus loads (CT <18) were observed for the 0–3 yo and the 12–17 yo groups at the same time point after symptom onset, as compared to the 4–6 yo and the 7–11 yo groups (Figure).

Figure

Duration of symptoms (days) at time of PRC swab collection for PCR

Table

Relative frequencies of positive PCR tests for SARS-CoV-2 in the different age groups and time periods as compared to the absolute test numbers

The percentage of the children/adolescents with PCR testing who reported at least one contact with a SARS-CoV2–infected person was about 2% at the beginning of the study, and about 13% starting from October 2020. A positive contact history increased the probability of SARS-CoV-2 detection (1:6; OR, 7.34; 95% CI [5.7, 9.45]). In children/adolescents without a history of contact, only every 24th test was positive in the 4th quarter of 2020; for those with a history, every 8th test was positive, whereby the risk of intrafamily transmission (1:2) was significantly higher than that from school or daycare contacts (1:14). Finally, children of parents working in high-risk professions tested positive for the virus less often (OR, 0.75; 95% CI [0.55, 0.99]), even though the percentage of these parents who were vaccinated was still low.

Discussion

This descriptive study evaluated the SARS-CoV-2 infection rates in children/adolescents with acute infections, the SARS-CoV-2 viral load in different age groups, and the relevance of contact with infected people within and outside the family. Notably, the group of very young children (0–3 yo) was tested more than the other groups of children in our collective. This is probably due to an increased presentation and testing of symptomatic very young children in practices as compared to presumably more frequent testing of young people in test centers. The SARS-CoV-2 infection numbers of symptomatic cases in the 4–6 yo, 7–11 yo, and 12–17 yo groups rose and fell in parallel with the overall incidence of the region (1), while that of the 0–3 yo group showed a smaller decrease.

During the lockdown, there was an almost complete reduction in the number of cases of infections in individuals from preschool age starting at the end of January 2021. This underscores the effectiveness of the lockdown measures in reducing the infection rates also in children. After the measures were relaxed, there was a renewed increase in the number of infections in all age groups.

Our findings show an increased viral load in the symptomatic 0–3 yo and 12–17 yo groups, and thus a potentially increased infectivity. Differences in viral loads between the age groups have been reported differently in two pediatric studies of symptomatic children (2, 3). This apparent discrepancy could be explained by the distinct timing of testing after symptom onset.

An American study (4) reported similar viral loads in symptomatic children and adults in mid-2020.

The number of known contacts with SARS-CoV-2–infected people in the study collective has increased several times for all age groups starting in October 2020, which could also reflect a change in the testing strategy in practices. In symptomatic children of all age groups, intrafamily contact with an infected person was reported in half of the cases.

The activity of parents in high-risk professions was negatively associated with the risk of infection in children and adolescents, even with a small number of vaccinated parents. This can possibly be explained by a bias of more frequent testing of symptomatic children of these parents.

Folke Brinkmann, Anne Schlegtendal, Anna Hoffmann Katharina Theile, Felicitas Hippert, Roland Strodka, Nina Timmesfeld, Hans H. Diebner, Thomas Lücke*, Christoph Maier*
University Hospital of Pediatrics and Adolescent Medicine, Ruhr University Bochum,
Bochum, Germany (Brinkmann, Schlegtendal, Hoffmann, Theile, Lücke, Maier)

Pediatric Practice Dönig-Kling, Bochum, Germany (Hippert)

Pediatric Practice Strodka-Henschel, Bochum, Germany (Strodka)

Department of Medical Informatics, Biometry and Epidemiology, Ruhr
University Bochum, Bochum, Germany (Timmesfeld, Diebner)

*These authors share last authorship.

Conflict of interest statement

Dr. Brinkmann has received meeting participation fees from GPP, Abbvie, and Nappa, and lecture fees from Nappa and Abbvie.

The remaining authors declare that no conflict of interest exists.

Manuscript received on 26 February 2021, revised version accepted on 4 May 2021.

Translated from the original German by Veronica Raker, PhD.

Cite this as:
Brinkmann F, Schlegtendal A, Hoffmann A, Theile K, Hippert F, Strodka R, Timmesfeld N, Diebner HH, Lücke T, Maier C: SARS-CoV-2 infections among children and adolescents with acute infections in the Ruhr region. Dtsch Arztebl Int 2021; 118: 363–4. DOI: 10.3238/arztebl.m2021.0227

References

1. Robert- Koch–Institut: SurvStat@RKI. Abfrage der Meldedaten nach Infektionsschutzgesetz (IfSG) über das Web. 2021. www.rki.de/DE/Content/Infekt/SurvStat/survstat_node.html (last accessed on 30 April 2021).

2. Hurst JH, Heston SM, Chambers HN, et al.: SARS-CoV-2 infections among children in the biospecimens from respiratory virus-exposed kids (BRAVE Kids) study. Clin Infect Dis 2020; ciaa1693

3. Kociolek LK, Muller WJ, Yee R, et al.: Comparison of upper respiratory viral load distributions in asymptomatic and symptomatic childrend diagnosed with SARS-CoV-2 infection in pediatric hospital testing programs. J Clin Microbiol 2020; 59: e02593–20

4. Baggio S, L‘Huillier AG, Yerly S, et al.: SARS-CoV-2 viral load in the upper respiratory tract of children and adults with early acute COVID-19. Clin Infect Dis 2020: ciaa1157