Flattening the curve in 52 days: characterisation of the COVID-19 pandemic in the Principality of Liechtenstein – an observational study

Abstract

BACKGROUND The principality of Liechtenstein had its first COVID-19 case at the beginning of March 2020. After exponential growth, the pandemic’s first wave was contained, with the last case being diagnosed 52 days after the initial occurrence. AIM To characterise the COVID-19 pandemic in Liechtenstein. METHODS All patients diagnosed in Liechtenstein were followed up until recovery and again 6–8 weeks after symptom onset. They were contacted every 2 days to record their clinical status until the resolution of their symptoms. The diagnosis of COVID-19 was based on clinical symptoms and molecular testing. Household and close workplace contacts were included in the follow-up, which also comprised antibody testing. In addition, public health measures installed during the pandemic in Liechtenstein are summarised. RESULTS During the first wave, 5% of the population obtained a reverse transcriptase polymerase chain reaction test. A total of 95 patients (median age 39 years) were diagnosed with COVID-19 (82 who resided in Liechtenstein), resulting in an incidence in Liechtenstein of 0.211%. One patient, aged 94, died (mortality rate 1%). Only 62% of patients could retrospectively identify a potential source of infection. Testing the patients’ household and close workplace contacts (n = 170) with antibody tests revealed that 25% of those tested were additional COVID-19 cases, a quarter of whom were asymptomatic. Those households which adhered to strict isolation measures had a significantly lower rate of affected household members than those who didn’t follow such measures. The national public health measures never restricted free movement of residents. Masks were only mandatory in healthcare settings. The use of home working for the general workforce was promoted. Gatherings were prohibited. Schools, universities, certain public spaces (like sports facilities and playgrounds), childcare facilities, nonessential shops, restaurants and bars were closed. Social distancing, hygienic measures, solidarity and supporting individuals who were at risk were the main pillars of the public health campaigns. CONCLUSION The close collaboration of all relevant stakeholders allowed for the complete workup of all COVID-19 patients nationwide. A multitude of factors (e.g., young age of the patients, low-threshold access to testing, close monitoring of cases, high alertness and adherence to public health measures by the population) led to the early containment of the first wave of the pandemic, with a very low rate of serious outcomes. Antibody testing for SARS-CoV-2 revealed a substantial proportion of undiagnosed COVID-19 cases among close contacts of the patients.

Characterization of a Pan-Immunoglobulin Assay Quantifying Antibodies Directed against the Receptor Binding Domain of the SARS-CoV-2 S1-Subunit of the Spike Protein: A Population-Based Study

“…The first cohort (COVID-FL) consisted of individuals who were investigated for SARS-CoV-2 infection during the first wave of the pandemic, which lasted from 2 March until 23 April 2020, and who had follow-up samples for serological SARS-CoV-2 antibody testing available. A detailed description of the cohort is provided in [4,22]. In brief, this first cohort consisted of all of the country's COVID-19 cases, their household contacts, and their close working contacts (n = 261).…”

“…Patients from the COVID-FL cohort as well as their household and close working contacts were closely followed every two to three days by telephone until recovery, and demographic, anthropometric and clinical data were collected. The details of this cohort have been described in detail in [4]. The individuals of this cohort had venous blood drawn for serological analysis for SARS-CoV-2 antibodies with different test formats.…”

“…In patients with a high clinical suspicion of COVID-19 with a negative RT-PCR result for SARS-CoV-2, demonstrating the presence of antibodies against SARS-CoV-2 can resolve a diagnostic dilemma and overcome the problem of false negative RT-PCR [2]. Because SARS-CoV-2 infection has also been shown to have an asymptomatic or oligosymptomatic course, antibodies against SARS-CoV-2 have proven to be a valuable tool to assess the seroprevalence of SARS-CoV-2 infection either in the total population, in healthcare workplace settings or in general workplace settings [3][4][5]. Serological testing facilitates surveillance and assists in the identification of individuals susceptible to COVID-19 infection [6,7].…”

Characteristics of Three Different Chemiluminescence Assays for Testing for SARS-CoV-2 Antibodies

“…This group was used for the determination of sensitivity. The method of RT-PCR measurement has been conducted as reported elsewhere [ 37 ]. The patients from Liechtenstein were prospectively and consecutively enrolled within a national COVID-19 cohort, whereas the Swiss patients consisted from a retrospectively assembled convenience sample, both detailed in references [ 37 , 38 ].…”

“…The method of RT-PCR measurement has been conducted as reported elsewhere [ 37 ]. The patients from Liechtenstein were prospectively and consecutively enrolled within a national COVID-19 cohort, whereas the Swiss patients consisted from a retrospectively assembled convenience sample, both detailed in references [ 37 , 38 ]. The second group of individuals was prospectively assembled and consisted of consecutive healthy blood donors from the Blutspendedienst Graubünden without clinical suspicion of COVID-19 providing blood for testing SARS-CoV2 antibodies from April 15th to May 4th, 2020 ( n = 191).…”