Introduction

Current knowledge suggests that children and young adults infected with SARS-CoV-2 are more often asymptomatic, or have fewer and milder symptoms than older patients 1-3. Children and teens between 10 and 19 years may be more likely to spread the virus among family members than adults and younger children 4. As PCR testing is mainly performed on symptomatic patients, those in need of hospitalization, patients at risk, and among health care workers, the prevalence and rate of transmission in young asymptomatic individuals is still largely unknown. So far, SARS-CoV-2 testing has not been performed systematically on asymptomatic groups. Accurate estimates of infection within different population groups is crucial for health authorities when deciding how and when to close and reopen societies during the COVID-19-pandemic.
Military service in Norway is mandatory for all men and women, and annually between 7000 and 8000 conscripts undergo military conscription5. Enrollment of new conscripts is a continuous process within the Norwegian Armed Forces to secure redundancy of troops. In Norway, public infection control measures have successfully curbed the rates of hospital admissions and deaths by COVID-194. Military training and service are not compatible with public COVID-19 infection control measures, as service personnel live close together in barracks, and combat training involves body contact. To ensure military training and the health of military personnel, stricter infection control measures to detect and prevent SARS-CoV-2 transmission within the Norwegian Armed Forces were implemented before and at enrollment to military service in mid-April 2020. The measures included a pre-enrollment telephone interview and self-imposed quarantine before enrollment, as well as serial SARS-CoV-2 PCR and serology testing during a six weeks training period.
We present the results and discuss the value of the extended infection control measures applied by the Norwegian Armed Forces Joint Medical Services in April 2020.
We also present the seroprevalence of SARS-CoV-2 in 1170 young military conscripts and the dynamic changes in antibody levels over six weeks.