Severe acute respiratory syndrome coronavirus 2 prevalence in 1170 asymptomatic Norwegian conscripts

Einar Kristian Borud; Espen Rostrup Nakstad; Siri Eldevik Håberg; Andreas Lind; Elin Anita Fadum; Arne Michael Taxt; Anneke Steens; Gaute Eriksen Gjein; Magne Wiken Sunde; Petter Iversen; Marius Svanevik; Babar Mushtaq Ahmad; Thomas Waldow; Arne Johan Norheim

doi:10.1002/hsr2.233

Severe acute respiratory syndrome coronavirus 2 prevalence in 1170 asymptomatic Norwegian conscripts

Health Sci Rep. 2021 Jan 15;4(1):e233. doi: 10.1002/hsr2.233. eCollection 2021 Mar.

Authors

Einar Kristian Borud^{1

2}, Espen Rostrup Nakstad³, Siri Eldevik Håberg⁴, Andreas Lind³, Elin Anita Fadum¹, Arne Michael Taxt³, Anneke Steens⁴, Gaute Eriksen Gjein¹, Magne Wiken Sunde¹, Petter Iversen¹, Marius Svanevik¹, Babar Mushtaq Ahmad¹, Thomas Waldow¹, Arne Johan Norheim^{1

2}

Affiliations

¹ Norwegian Armed Forces Joint Medical Services Sessvollmoen Norway.
² Department of Community Medicine University of Tromsø-The Arctic University of Norway Tromsø Norway.
³ Oslo University Hospital Oslo Norway.
⁴ Norwegian Institute of Public Health Oslo Norway.

Abstract

Background: Accurate estimates of SARS-CoV-2 infection in different population groups are important for the health authorities. In Norway, public infection control measures have successfully curbed the pandemic. However, military training and service are incompatible with these measures; therefore extended infection control measures were implemented in the Norwegian Armed Forces. We aimed to describe these measures, discuss their value, and investigate the polymerase chain reaction (PCR) prevalence and seroprevalence of SARS-CoV-2, as well as changes in antibody titer levels over the 6-week military training period in a young, asymptomatic population of conscripts.

Methods: In April 2020, 1170 healthy conscripts (median age 20 years) enrolled in military training. Extended infection control measures included a pre-enrollment telephone interview, self-imposed quarantine, questionnaires, and serial SARS-CoV-2 testing. At enrollment, questionnaires were used to collect information on symptoms, and SARS-CoV-2 rapid antibody testing was conducted. Serial SARS-CoV-2 PCR and serology testing were used to estimate the prevalence of confirmed SARS-CoV-2 and monitor titer levels at enrollment, and 3 and 6 weeks thereafter.

Results: At enrollment, only 0.2% of conscripts were SARS-CoV-2 PCR-positive, and seroprevalence was 0.6%. Serological titer levels increased nearly 5-fold over the 6-week observation period. Eighteen conscripts reported mild respiratory symptoms during the 2 weeks prior to enrollment (all were PCR-negative; one was serology-positive), whereas 17 conscripts reported respiratory symptoms and nine had fever at enrollment (all were PCR- and serology-negative).

Conclusions: The prevalence of SARS-CoV-2 was less than 1% in our sample of healthy Norwegian conscripts. Testing of asymptomatic conscripts seems of no value in times of low COVID-19 prevalence. SARS-CoV-2 antibody titer levels increased substantially over time in conscripts with mild symptoms.

Keywords: Armed Forces; COVID‐19; SARS‐CoV‐2; adolescents; conscripts; coronavirus; prevalence; serological analyses; serology; youths.