Predictors of SARS-CoV-2 Infection in Youth at a Large, Urban Healthcare Center in California, March-September 2020

Epidemiology and SARS-CoV-2 Infection Patterns among Youth Followed at a Large Los Angeles Health Network during 2020-2022: Clinical Presentation, Prevalent Strains, and Correlates of Disease Severity

BACKGROUND

Outcomes of SARS CoV-2 infection in infants, children and young adults are reported less frequently than in older populations. The evolution of SARS-CoV-2 cases in LA County youths followed at a large health network in southern California over two years was evaluated.

METHODS

A prospective cohort study of patients aged 0-24 years diagnosed with COVID-19 was conducted. Demographics, age distribution, disease severity, circulating variants of concern (VOCs), and immunization rates were compared between first and second pandemic years. Logistic regression estimated odds ratios (OR) and 95% confidence intervals (CI) of factors associated with severe/critical COVID-19.

RESULTS

In total, 61,208 patients 0-24 years of age were tested for SARS-CoV-2 by polymerase chain reaction (PCR); 5263 positive patients (8.6%) with available data were identified between March 2020 and March 2022. In Year 1, 5.8% (1622/28,088) of youths tested positive, compared to 11% (3641/33,120) in Year 2 (p < 0.001). Most youths had mild/asymptomatic illness over two years. SARS-CoV-2 positivity was >12% across all age groups in the second half of Year 2, when Omicron prevailed. Pulmonary disease was associated with higher risk of severe COVID-19 in both years (OR: 2.4, 95% CI: 1.4-4.3, p = 0.002, Year 1; OR: 11.3, 95% CI: 4.3-29.6, Year 2, p < 0.001). Receipt of at least one COVID-19 vaccine dose was protective against severe COVID-19 (OR: 0.3, 95% CI: 0.11-0.80, p < 0.05).

CONCLUSIONS

Despite different VOCs and higher rates of test positivity in Year 2 compared to Year 1, most youths with COVID-19 had asymptomatic/mild disease. Underlying pulmonary conditions increased the risk of severe COVID-19, while vaccination was highly protective against severe disease in youths.

Clinical and epidemiological characteristics of SARS-CoV-2 Infection in Los Angeles County youth during the first year of the pandemic

OBJECTIVES

The aim of this study was to characterize SARS-CoV-2 infection patterns in Los Angeles (LA) County youth followed at our institution during the first pandemic year.

DESIGN

A prospective cohort of patients aged < 25 years who tested positive for SARS-CoV-2 using reverse-transcriptase polymerase chain reaction (RT-PCR) assays between March 13, 2020, and March 31, 2021, was evaluated at a large LA County health network. Demographics, age distribution, and disease severity were analyzed.

RESULTS

There were 28,088 youth aged < 25 years tested for SARS-CoV-2 using RT-PCR, with 1849 positive results identified (7%). Among the positive results, 475 of 11,922 (4%) were identified at the pandemic onset (March-September 2020) (Cohort 1) and 1374 of 16,166 (9%) between October 2020 and March 2021 (Cohort 2), P < 0.001. When disease severity was compared across cohorts, Cohort 2 had a greater proportion of asymptomatic and mild/moderate disease categories than Cohort 1 (98% vs 80%, respectively); conversely, Cohort 1 had a near-10-fold higher proportion of severe disease than Cohort 2 (17% vs 1.8%). Cohort 2 comprised younger patients with a mean age of 13.7 years vs 17.3 years in Cohort 1. Older age was associated with a higher percentage of infection, with 63% of all confirmed cases found in participants aged 19 to 25 years in Cohort 1, compared with 38% of confirmed cases in Cohort 2. Age increase was also associated with greater disease severity by linear regression modeling (P< 0.001).

CONCLUSION

Coronavirus disease 2019 (COVID-19) disease severity in youth decreased over time in LA County during the first pandemic year, likely a reflection of changing demographics, with younger children infected. A higher infection rate in youth did not lead to higher disease severity over time.