CON-VINCE (COvid-19 National survey for assessing VIral spread by Non-affected CarriErs) is a national project aiming to evaluate the dynamics of the spread of the COVID-19 disease within the Luxembourgish population.

“CON-VINCE” was launched in April 2020 as one of the several initiatives put in place under the aegis of the Research Luxembourg COVID-19 task force to help contain the current pandemic. By screening a statistically representative panel of volunteers for the presence of the SARS-CoV-2 virus, the study will identify asymptomatic and mildly symptomatic individuals and follow them up for a year.

Ultimately, the study aims to generate accurate data on the prevalence and transmission of the disease, assisting policy-makers in taking evidence-based decisions over the course of the coming weeks.  

CON-VINCE June 2020 Newsletter (DE; ENG; FR)
Why is this research important?

Asymptomatic individuals – often referred to as “silent carriers” – and mildly symptomatic carriers play a significant role in the spread of the SARS-CoV-2 virus. However, they currently remain largely unassessed, since diagnostic testing is performed predominantly on people with clear COVID-19 symptoms. In order to put in place effective measures to stave off the COVID-19 infection, it is crucial to systematically test a representative sample of the population in order to identify all individuals carrying the SARS-CoV-2 virus, regardless of their symptoms.


CON-VINCE Study – Behind the scenes (PART I)

CON-VINCE as a role model for translational research collaboration in Luxembourg (PART I) IBBL a as key integrator On 8th April, the CON-VINCE study was officially launched, with the aim to assess the spread dynamics of the COVID-19 disease among the Luxembourgish population. Only 2 days later, all necessary material for starting up was already available (many […]

CON-VINCE study results – second testing phase

CON-VINCE, a national research project aiming to evaluate the prevalence and dynamics of the spread of COVID-19 within the Luxembourgish population, was launched at the beginning of April under the umbrella of the Research Luxembourg COVID-19 Task Force. The second round of testing of the participants in the study (first follow-up after baseline testing) showed […]

First results of the CON-VINCE study

CON-VINCE, a national research project aiming to evaluate the prevalence and dynamics of the spread of the COVID-19 disease within the Luxembourgish population, was launched at the beginning of April under the umbrella of the Research Luxembourg COVID-19 Task Force. Following the successful recruitment and first testing effort of more than 1800 participants over the […]

Aim and design of the research

In this context, “CON-VINCE” aims to provide reliable information on the nature, prevalence and transmission modality of COVID-19 in Luxembourg, therefore guiding national and international decision-makers in mounting an effective public health, political and economic response to the pandemic. The project will also enable the tracking of the psychological and socio-economic impact of long-term containment measures on the general population.

The study will test a panel of approximately 1,500 participants over the age of 18 and detect the three main groups of asymptomatic or mildly symptomatic people, namely:

  • individuals who are “virus-free” and therefore asymptomatic;
  • people who are currently infected but present mild or no symptoms;
  • and those who were infected but are at present free of the virus.

Participants testing positive for SARS-CoV-2 but displaying mild or no symptoms will be followed up over one year, together with virus-free individuals. Conversely, symptomatic patients will be excluded from the study and undergo regular treatment instead.

Your participation

The choice of participants in the panel needs to accurately reflect the actual composition of the Luxembourgish population in terms of age, gender and geography, in order to avoid biased and statistically inaccurate results. Therefore, LIH will not contact eligible candidates directly to participate in the study. At this stage, participation of volunteers from the general population is unfortunately not yet possible.

Frequently Asked Questions (FAQ)
What is a longitudinal study. And why do I have to take part repeatedly?

Longitudinal means that participants are invited repeatedly within a study to follow them over time. While most prevalence studies around the world only offer a one-time snapshot to participants, the CON-VINCE study is unique since it has incorporated such clinical research follow-ups over time. This allows to (i) be up to date with clinical information of the participants in a changing environment, (ii) repeatedly check their respective health status and draw conclusions on how the virus spread, immune response and/or symptoms of the disease evolve over time. This goes far beyond the results that can be gained from a single diagnostic approach in large-scale testing offered to the entire population outside clinical research studies. For research, your repeated participation is particularly important as so far little is known about the mid- to long-term effects of the SARS-CoV-2 virus. For the success of the CON-VINCE study, it is therefore crucial that the same participants are contributing data and biosamples every 2 weeks over the course of 2 months and then once more after 1 year for assessing longterm developments.

Which tests are done as part of the study?

Besides filling in different questionnaires, participants will undergo 2 different types of tests, which are both crucial for participation:
• The PCR tests aim to detect the presence of the SARS-CoV-2 virus. A positive result means that a person currently carries the virus. This is done based on a nasopharyngeal swab.
• The serology test aims to detect the presence of antibodies against the SARS-CoV-2 virus. A positive test result means that you may have been in contact with the novel Coronavirus and your body may have developed an immune reaction.

How reliable is the serology test to identify antibodies against SARS-CoV-2?

The CON-VINCE study uses the Euroimmun Anti-SARS-CoV-2 Elisa (IgG and IgA) tests for this purpose. IgA and IgG are two different classes of antibodies that are produced at different stages of the immune response.
The test sensitivity is defined as the ability of a test to correctly identify those with the disease (true positive rate). The supplier states that the sensitivity of the test improves with increased time after infection and when considering the combined results of both IgA and IgG antibodies against SARS-CoV-2: For samples taken >10days after infection in which both IgA and IgG antibodies are considered a sensitivity of 100% can be achieved.
The test specificity is defined as the ability of a test to correctly identify those without the disease (true negative rate). The supplier states that the Anti-SARS-CoV-2 Elisa (IgG) yields a specificity of 98,5%, while the Anti-SARS-CoV-2 Elisa (IgA) yields a specificity of 92,5%. For details, please consider the manual issued by the supplier.
A scientific publication ( recently reported a detailed examination of the Euroimmun test used in the CON-VINCE study. It demonstrated that the results obtained by the IgG kits were highly reliable and reproducible.

How reliable is the PCR-test to detect the presence of the SARS-CoV-2 virus?

The CON-VINCE study uses the Seegene Allplex nCoV-2019 qPCR as primary tests for this purpose, which identifies viral genomic material in the nasal-pharyngal swab. In addition, generic qPCR tests, which are based on recommendations of the WHO or the Centers for Disease Control (CDC), and the Fast Track Diagnostics qPCR test are used as confirmation tests in the CON-VINCE study. The sensitivity for this primary test, i.e., the ability of the test to correctly identify virus-positive samples (true positive rate), is 100% (according to under optimized laboratory conditions. The test specificity, i.e., the ability of the test to correctly identify virus-negative samples (true negative rate), is also 100% (according to ) under optimized laboratory conditions.

In the real world, outside a study like CON-VINCE, testing conditions and processes are far from perfect, and accuracy suffers. Researchers still don’t know what the real-world false positive rate is, but the clinical sensitivity of RT-PCR tests ranges from 66% to 80% ( That means between one in three and one in five infected people who are tested will receive false-negative results under real-world conditions.

Serology testing is now also offered by different laboratories. What is the difference in participating in serological testing in CON-VINCE?

In the CON-VINCE study, we test for different (IgG and IgA) antibodies repetitively over time, which due to individual follow-up examinations of each participant and inclusion of additional clinical and virus-diagnostic information, will allow for an interpretation related to the immune response. In case of a positive result, a medical doctor from the CON-VINCE study will contact you in case you have a positive antibody test. All tests performed within the CON-VINCE study are free of charge for the participant.
Most importantly, your participation is of utmost importance to advance our understanding of the new coronavirus SARS-CoV-2 and – besides informing you about your own status – will contribute to more effectively fighting the COVID-19 pandemic.

I would like to join the study. Is it still possible to participate now in the CON-VINCE study?

Unfortunately, the specific design of the CON-VINCE study does not foresee to recruit volunteers but is based on a defined representative panel of Luxembourg’s population. The choice of participants in the panel needs to accurately reflect the actual composition of the Luxembourgish population in terms of age, gender, and residency, in order to deliver unbiased and statistically accurate results. This task will be conducted by TNS Ilres in collaboration with the competence centre for methods and statistics of the LIH. Here the LIH, as coordinator of the study, will not contact eligible candidates directly to participate in the study. Therefore, the participation of volunteers from the general population is unfortunately not possible at this stage.

How representative is the panel used to recruit the CON-VINCE study cohort?

The CON-VINCE study aims to record the situation in the population as representative as possible and – due to the pandemic – as quickly as possible within a sample. When designing the study of each research study, different criteria with different priorities need to be weighed up and met as best as possible. Our study focuses on the criteria of age, gender, and residence. Other factors such as level of education, social status, lifestyle habits, etc. could not be taken into account in the time, organizational and financial framework of the CON-VINCE study. Taking further criteria into account would, e.g., result in a significantly larger number of participants required to be able to make statistical statements for each subgroup.

A. I am a participant in the CON-VINCE study
Will the CON-VINCE study team communicate the results of the PCR and antibody tests?

As detailed in the study information, in case of virus-positive results, one of our medical doctors will call you within 48h after testing for explaining the result and will also inform your treating physician. If you don’t hear from us within this time frame, you do currently not carry the SARS-CoV-2 virus. Also, positive results from antibody testing will be communicated, typically within 2 weeks after biosampling.

Why does the CON-VINCE study team not communicate all results?

Within the research study, the communication of research results back to participants is not generally foreseen as – differently to regular laboratory diagnostics – the participants remain de-identified for all analyses. Therefore, re-identification (assigning results to names) is an exception and only justified by clinically relevant information, e.g., infection with SARS-CoV-2 virus. Then the medical doctors of the study team can get access to the participants’ identity to inform them about positive test results. Rest assured, though, that all positive results will be communicated to you and your treating physician for clinical follow-up as described above.

I had a positive antibody test. What does this mean for my immune status?

It is important to understand that the presence of antibodies in your blood, even if clearly against SARS-CoV2, does not necessarily mean that you are immune as some people have tested positive for the virus more than once. Further research is needed to better understand if and for how long antibodies protect against the virus. Furthermore, it is not known whether you could transmit the virus even though you have developed antibodies. Therefore, you need to stick to the precaution measures (e.g., 2m distance, frequent hand washing, masks, etc.) recommended by the Luxembourgish government (

Should my family members get tested for antibodies if I tested positive?

No, your family currently does not need to get tested, as for now, it has no clinical implication and, therefore, does not require specific care.
Currently, antibody testing is more important in clinical research because it is not known yet whether it is possible to acquire immunity after the infection and because the tests cannot show whether the antibodies formed are protective.

In what cases will be my treating physician be informed?

Whenever there is a new positive result, your treating physician will be informed. For the swab results, this will be done as soon as possible (within 48 hours), since it requires an independent test and might mean you have to isolate.
For antibody results, it will typically take 2 weeks. We first inform you about the results and consecutively send out a letter to your treating physician as soon as possible.

Do I have to see my treating physician when receiving a positive antibody test result?

No, this information currently has no direct implication. Also, it is still not known whether a positive antibody status indicates immunity. If this should become relevant due to additional information obtained during the CON-VINCE analyses, we will get in touch with you. Please keep following the general safety measures (social distancing, masks, hand-washing, etc.) communicated by the government.

What happens to my data?

Your personal data is collected and analysed to achieve the scientific objectives of the study (analysis of epidemiological, socio-economic and psychological aspects of the confinement during the pandemic). We ensure the protection of your data in accordance with the General Data Protection Regulation (EU) 2016/679 of 27 April 2016, applicable as of 25 May 2018, known as the “GDPR”. Detailed information about data processing can be found in the information questionnaire. If you have questions concerning the processing of your personal data by the LIH or LCSB/UL, you can contact the Data Protection Officer by e-mail at or

Why should I contribute with stool samples to the CON-VINCE study?

The gut microbiota is crucial for the immune system function, helping to keep harmful pathogens away. The SARS-CoV-2 virus has been found in stool samples of infected individuals with or without respiratory symptoms. Studies* indicate that the stool samples may be positive for the virus even after the naso-pharyngeal swabs turned negative. The gut microbiota could influence the outcome of COVID-19 disease.


I am back at work; how can I still make sure to contribute to the important biosampling?

Please try to visit the chosen laboratory on the assigned date. This helps us to better estimate the workload and adapt the capacities of the laboratories accordingly. If this should not be possible, you can choose to go to any other laboratory on the list within the same week. View address & opening hours of eligible labs (PDF)

Can I go to another lab or plan for the sample collection at home with the same voucher?

Yes, your voucher is valid for the whole recruitment wave and all laboratories on the list, including collection at home.

I did not receive the questionnaire on the expected day; what should I do?

It is possible that there were minor changes to the planning because of several bank holidays in May and June. Therefore, a few days of delay is possible and foreseen in the study design. If you suspect that something might have gone wrong, you can always write to our partner TNS-Ilres (, and they will get back to you with detailed information.

Can I get a certificate for work?

Yes, please simply ask the laboratories that you attend for biosampling. They will provide a certificate confirming your participation in the study and your presence in the laboratory that day.

Why do you ask personal questions about youth and childhood experiences (abuse, etc.) in the last participation of the CON-VINCE study and how does this relate to the COVID-19 pandemic?

Indeed, we have a included such an optional questionnaire in the last participation round, which you do not have to answer if you do not feel comfortable with the questions. We are asking personal questions about youth and childhood experiences (abuse, etc.) in the context of the coronavirus pandemic because there is a lot of evidence that such experience can determine a person’s lifelong health and disease profile. Short-term impacts of such adversities can be seen in a range of behavioural, health, cognitive and learning outcomes immediately after exposure in childhood. In addition, early life experience has a much longer-term impact that can be seen in adults up to 60 years later. Studies on people who suffered adverse experiences and chronic stress in childhood have shown that it can lead to a much greater susceptibility to stress-related physical illness in adult life (such as cardiovascular disease, stroke, cancer and diabetes) as well as mental health problems (such as depression, anxiety disorders and substance abuse). It also has a major impairing effect on the immune and inflammation systems – which is important to study in the context of the COVID-19 pandemic.

By asking these questions, we would like to understand two things:

  1. Does the early life environment influences both the patient’s psychological and emotional state during the pandemic lockdown?
  2.  Do adverse early life events alter the immune system to an extend that it increases the susceptibility to COVID-19?

Luxembourg researchers have a strong expertise in understanding how our social environment links through to disease many years later and could hence contribute to better understand COVID-19 susceptibility.

These optional questions only need to be asked once as they cover events that happened many years ago. This is why we included them only in the last questionnaire.

You can find out more about the science behind this here:

B. I am a treating physician
Why do I receive results?

Within the CON-VINCE study, we communicate virus- or serology-positive results to both the patients as well as his indicated treating physician. This is particularly relevant for virus-positive results, where clinical care may be necessary.

My patient has a positive or inconclusive PCR test result. Do I have to undertake any further diagnostic steps?

We take care of a confirmatory diagnostic test in case of a positive result, and you will obtain a copy of the diagnostic test result. If your patient is positive, he/she will need to follow the isolation guidelines as foreseen by the Ministry of Health.

My patient has a positive IgA/IgG antibody test result. Do I have to undertake any further diagnostic steps?

In the case of positive IgA or IgG antibody, currently, no further tests are needed. This is just to inform you that your patient was probably in contact with the virus.

Will I only be informed about positive results?

Yes. We do not contact the patient nor the treating physician in case of negative results.


The “CON-VINCE” study is led by a consortium of Luxembourgish research institutions, including:

The study is supported by the Luxembourg National Research Fund (FNR) with EUR 1.4 million co-financing. Also supported by the André Losch Fondation. The market research company TNS-ILRES, Ketterthill, Laboratoires Réunis and BioneXt Lab are associated partners in the study.

“CON-VINCE” is implemented under the aegis of the Research Luxembourg COVID-19 task force.

Research Luxembourg is a joint initiative of the main players in Luxembourg public research Luxembourg Institute of Health (LIH); Luxembourg Institute of Socio-Economic Research (LISER); Luxembourg Institute of Science and Technology (LIST); Laboratoire National de santé (LNS); University of Luxembourg; Fonds National de la Recherche (FNR), supported by the Ministry of Higher Education and Research. The main aim of the initiative is to promote scientific cooperation in Luxembourg and to communicate the activities of the sector as a whole.



Prof Rejko Krüger:


Didier Goossens: