Extensive SARS-CoV-2 testing reveals BA.1/BA.2 asymptomatic rates and underreporting in school children

Area of Science:

• Public Health
• Epidemiology
• Virology

Background:

• The coronavirus disease 2019 (COVID-19) pandemic posed challenges in accurately tracking cases, particularly among school children.
• Underreporting of COVID-19 cases in K-12 students may have been significant, impacting public health response evaluation.
• An Omicron variant (BA.1/BA.2) outbreak in Newfoundland and Labrador prompted recommendations for student rapid antigen testing.

Purpose of the Study:

• To estimate the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in K-12 students.
• To assess the extent of case underreporting in school children during the Omicron outbreak.
• To identify the proportion of asymptomatic infections among students.

Main Methods:

• A province-wide online survey was administered to parents/guardians to collect rapid antigen test (RAT) results from K-12 students.
• Survey data on RAT results were compared with official provincial case and testing data.
• Prevalence of infection, underreporting ratios, and asymptomatic infection rates were calculated.

Main Results:

• The provincial testing system captured only 1 in 4.3 positive households, indicating substantial underreporting.
• Rapid antigen tests estimated a 5.1% positivity rate, significantly higher than the 1.2% reported by the provincial system.
• Asymptomatic infections constituted 59.8% of all positive cases identified through RATs.
• Elementary school students accounted for 62.9% of positive cases.

Conclusions:

• The study highlights significant underreporting of COVID-19 cases in school children, consistent with serology data.
• Findings provide crucial insights into infection prevalence and the high rate of asymptomatic infections in this understudied population.
• The low survey participation rate (3.5%) necessitates cautious interpretation of results due to potential sample selection bias.