Comparison of coronavirus antibody tests revealed too optimistic claims | University of Tartu

Contacts of UT units

Faculty of Arts and Humanities
Faculty phone: 
+372 737 5341
Faculty address: 
Jakobi 2, rooms 116–121, 51005 Tartu
  • Dean's Office
    Faculty phone: 
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    Faculty address: 
    Jakobi 2, rooms 116–121, 51005 Tartu
  • Institute of History and Archaeology
    Faculty phone: 
    +372 737 5651
    Faculty address: 
    Jakobi 2, 51005 Tartu
  • Institute of Estonian and General Linguistics
    Faculty phone: 
    +372 737 5221
    Faculty address: 
    Jakobi 2, 51005 Tartu
  • Institute of Philosophy and Semiotics
    Faculty phone: 
    +372 737 5314
    Faculty address: 
    Jakobi 2, rooms 309–352, 51005 Tartu
  • Institute of Cultural Research
    Faculty phone: 
    (+372) 737 5223
    Faculty address: 
    Ülikooli 16, 51003 Tartu
  • School of Theology and Religious Studies
    Faculty phone: 
    +372 737 5301
    Faculty address: 
    Ülikooli 18–310, 50090 Tartu
  • College of Foreign Languages and Cultures
    Faculty address: 
    J. Liivi 4, 50409, Tartu
  • Viljandi Culture Academy
    Faculty phone: 
    +372 435 5232
    Faculty address: 
    Posti 1, 71004 Viljandi
Faculty of Social Sciences
Faculty phone: 
+372 737 5957
Faculty address: 
Lossi 36, 51003 Tartu
  • Dean's Office
    Faculty phone: 
    + 372 737 5900
    Faculty address: 
    Lossi 36, 51003 Tartu
  • Institute of Education
    Faculty phone: 
    +372 737 6440
    Faculty address: 
    Salme 1a–29, 50103 Tartu
  • Johan Skytte Institute of Political Studies
    Faculty phone: 
    +372 737 5582
    Faculty address: 
    Lossi 36–301, 51003 Tartu
  • School of Economics and Business Administration
    Faculty phone: 
    +372 737 6310
    Faculty address: 
    Narva mnt 18, 51009 Tartu
  • Institute of Psychology
    Faculty phone: 
    +372 737 5902
    Faculty address: 
    Näituse 2, 50409 Tartu
  • School of Law
    Faculty phone: 
    +372 737 5390
    Faculty address: 
    Näituse 20–324, 50409 Tartu
  • Institute of Social Studies
    Faculty phone: 
    +372 737 5188
    Faculty address: 
    Lossi 36, 51003 Tartu
  • Narva College
    Faculty phone: 
    +372 740 1900
    Faculty address: 
    Raekoja plats 2, 20307 Narva
  • Pärnu College
    Faculty phone: 
    +372 445 0520
    Faculty address: 
    Ringi 35, 80012 Pärnu
Faculty of Medicine
Faculty phone: 
+372 737 5326
Faculty address: 
Ravila 19, 50411 Tartu
  • Dean's Office
    Faculty phone: 
    +372 737 5326
    Faculty address: 
    Ravila 19, 50411 Tartu
  • Institute of Biomedicine and Translational Medicine
    Faculty phone: 
    +372 737 4210
    Faculty address: 
    Biomeedikum, Ravila 19, 50411 Tartu
  • Institute of Pharmacy
    Faculty phone: 
    +372 737 5286
    Faculty address: 
    Nooruse 1, 50411 Tartu
  • Institute of Dentistry
    Faculty phone: 
    +372 731 9856
    Faculty address: 
    Raekoja plats 6, 51003 Tartu
  • Institute of Clinical Medicine
    Faculty phone: 
    +372 737 5323
    Faculty address: 
    L. Puusepa 8, 50406 Tartu
  • Institute of Family Medicine and Public Health
    Faculty phone: 
    +372 737 4190
    Faculty address: 
    Ravila 19, 50411 Tartu
  • Institute of Sport Sciences and Physiotherapy
    Faculty phone: 
    +372 737 5360
    Faculty address: 
    Jakobi 5–205, 51005 Tartu
Faculty of Science and Technology
Faculty phone: 
+372 737 5820
Faculty address: 
Vanemuise 46–208, 51014 Tartu
  • Dean's Office
    Faculty phone: 
    +372 737 5820
    Faculty address: 
    Vanemuise 46–208, 51003 Tartu
  • Institute of Computer Science
    Faculty phone: 
    +372 737 5445
    Faculty address: 
    Narva mnt 18, 51009 Tartu
  • Estonian Marine Institute
    Faculty phone: 
    +372 671 8902
    Faculty address: 
    Mäealuse 14, 12618 Tallinn
  • Institute of Physics
    Faculty address: 
    W. Ostwaldi 1, 50411 Tartu
  • Institute of Chemistry
    Faculty phone: 
    +372 737 5261
    Faculty address: 
    Ravila 14a, 50411 Tartu
  • Institute of Genomics
    Faculty phone: 
    +372 737 4000
    Faculty address: 
    Riia 23b, 51010 Tartu
  • Institute of Mathematics and Statistics
    Faculty phone: 
    +372 737 5860
    Faculty address: 
    Narva mnt 18, 51009 Tartu
  • Institute of Molecular and Cell Biology
    Faculty phone: 
    +372 737 5027
    Faculty address: 
    Riia 23, 23b–134, 51010 Tartu
  • Tartu Observatory
    Faculty phone: 
    +372 737 4510
    Faculty address: 
    Observatooriumi 1, Tõravere, 61602 Tartumaa
  • Institute of Technology
    Faculty phone: 
    +372 737 4800
    Faculty address: 
    Nooruse 1, 50411 Tartu
  • Institute of Ecology and Earth Sciences
    Faculty phone: 
    +372 737 5835
    Faculty address: 
    Vanemuise 46, 51003 Tartu
Institutions
  • Library
    Faculty phone: 
    +372 737 5702
    Faculty address: 
    W. Struve 1, 50091 Tartu
  • Youth Academy
    Faculty phone: 
    +372 737 5581
    Faculty address: 
    Uppsala 10, 51003 Tartu
  • Museum
    Faculty phone: 
    +372 737 5674
    Faculty address: 
    Lossi 25, 51003 Tartu
  • University of Tartu Natural History Museum and Botanical Garden
    Faculty phone: 
    +372 737 6076
    Faculty address: 
    Vanemuise 46, 51003 Tartu
Support Units
  • Administrative Office
    Faculty phone: 
    +372 737 5606
    Faculty address: 
    Ülikooli 18a, 51005 Tartu
  • Centre for Entrepreneurship and Innovation
    Faculty phone: 
    +372 737 4809
    Faculty address: 
    Narva mnt 18, 51009, Tartu
  • University Office in Tallinn
    Faculty phone: 
    +372 737 6600
    Faculty address: 
    Teatri väljak 3, 10143 Tallinn
  • Estates Office
    Faculty phone: 
    +372 737 5137
    Faculty address: 
    Ülikooli 18a, 51005 Tartu
  • Finance Office
    Faculty phone: 
    +372 737 5125
    Faculty address: 
    Jakobi 4, 51005 Tartu
  • Grant Office
    Faculty phone: 
    +372 737 6215
    Faculty address: 
    Raekoja plats 9, 51004 Tartu
  • Information Technology Office
    Faculty phone: 
    +372 737 6000, IT-help: +372 737 5500
    Faculty address: 
    Ülikooli 18a, 51005 Tartu
  • Human Resources Office
    Faculty phone: 
    +372 737 5145
    Faculty address: 
    Ülikooli 18, rooms 302 and 304, 50090 Tartu
  • Internal Audit Office
    Faculty address: 
    Ülikooli 18-244, 51005 Tartu
  • International Cooperation and Protocol Office
    Faculty phone: 
    +372 737 6123
    Faculty address: 
    Ülikooli 18, rooms 104, 301, 305, 50090 Tartu
  • Marketing and Communication Office
    Faculty phone: 
    +372 737 5687
    Faculty address: 
    Ülikooli 18, rooms 102, 104, 209, 210, 50090 Tartu
  • Office of Academic Affairs
    Faculty phone: 
    +372 737 5620
    Faculty address: 
    Ülikooli 18, 50090 Tartu
  • Procurement Office
    Faculty phone: 
    +372 737 6632
    Faculty address: 
    Ülikooli 18a, 51005 Tartu
  • Rector's Strategy Office
    Faculty phone: 
    +372 737 5600
    Faculty address: 
    Ülikooli 18, 50090 Tartu
  • Student Council
    Faculty address: 
    Ülikooli 18b, 51005 Tartu
  • University of Tartu Press
    Faculty phone: 
    +372 737 5945
    Faculty address: 
    W. Struve 1, 50091 Tartu
Other Units
  • University of Tartu Academic Sports Club
    Faculty phone: 
    +372 737 5371
    Faculty address: 
    Ujula 4, 51008 Tartu
  • Tartu Student Village
    Faculty phone: 
    +372 740 9959
    Faculty address: 
    Narva mnt 25, 51013 Tartu
  • Tartu Students’ Club
    Faculty phone: 
    +372 730 2400
    Faculty address: 
    Kalevi 24, 51010 Tartu
  • Tartu University Hospital
    Faculty address: 
    L. Puusepa 1a, 50406 Tartu
  • University of Tartu Foundation
    Faculty phone: 
    +372 737 5852
    Faculty address: 
    Ülikooli 18, 50090 Tartu
  • View all other units

Contacts of UT units

Faculty of Arts and Humanities
Faculty phone: 
+372 737 5341
Faculty address: 
Jakobi 2, rooms 116–121, 51005 Tartu
  • Dean's Office
    Faculty phone: 
    + 372 737 5341
    Faculty address: 
    Jakobi 2, rooms 116–121, 51005 Tartu
  • Institute of History and Archaeology
    Faculty phone: 
    +372 737 5651
    Faculty address: 
    Jakobi 2, 51005 Tartu
  • Institute of Estonian and General Linguistics
    Faculty phone: 
    +372 737 5221
    Faculty address: 
    Jakobi 2, 51005 Tartu
  • Institute of Philosophy and Semiotics
    Faculty phone: 
    +372 737 5314
    Faculty address: 
    Jakobi 2, rooms 309–352, 51005 Tartu
  • Institute of Cultural Research
    Faculty phone: 
    (+372) 737 5223
    Faculty address: 
    Ülikooli 16, 51003 Tartu
  • School of Theology and Religious Studies
    Faculty phone: 
    +372 737 5301
    Faculty address: 
    Ülikooli 18–310, 50090 Tartu
  • College of Foreign Languages and Cultures
    Faculty address: 
    J. Liivi 4, 50409, Tartu
  • Viljandi Culture Academy
    Faculty phone: 
    +372 435 5232
    Faculty address: 
    Posti 1, 71004 Viljandi
Faculty of Social Sciences
Faculty phone: 
+372 737 5957
Faculty address: 
Lossi 36, 51003 Tartu
  • Dean's Office
    Faculty phone: 
    + 372 737 5900
    Faculty address: 
    Lossi 36, 51003 Tartu
  • Institute of Education
    Faculty phone: 
    +372 737 6440
    Faculty address: 
    Salme 1a–29, 50103 Tartu
  • Johan Skytte Institute of Political Studies
    Faculty phone: 
    +372 737 5582
    Faculty address: 
    Lossi 36–301, 51003 Tartu
  • School of Economics and Business Administration
    Faculty phone: 
    +372 737 6310
    Faculty address: 
    Narva mnt 18, 51009 Tartu
  • Institute of Psychology
    Faculty phone: 
    +372 737 5902
    Faculty address: 
    Näituse 2, 50409 Tartu
  • School of Law
    Faculty phone: 
    +372 737 5390
    Faculty address: 
    Näituse 20–324, 50409 Tartu
  • Institute of Social Studies
    Faculty phone: 
    +372 737 5188
    Faculty address: 
    Lossi 36, 51003 Tartu
  • Narva College
    Faculty phone: 
    +372 740 1900
    Faculty address: 
    Raekoja plats 2, 20307 Narva
  • Pärnu College
    Faculty phone: 
    +372 445 0520
    Faculty address: 
    Ringi 35, 80012 Pärnu
Faculty of Medicine
Faculty phone: 
+372 737 5326
Faculty address: 
Ravila 19, 50411 Tartu
  • Dean's Office
    Faculty phone: 
    +372 737 5326
    Faculty address: 
    Ravila 19, 50411 Tartu
  • Institute of Biomedicine and Translational Medicine
    Faculty phone: 
    +372 737 4210
    Faculty address: 
    Biomeedikum, Ravila 19, 50411 Tartu
  • Institute of Pharmacy
    Faculty phone: 
    +372 737 5286
    Faculty address: 
    Nooruse 1, 50411 Tartu
  • Institute of Dentistry
    Faculty phone: 
    +372 731 9856
    Faculty address: 
    Raekoja plats 6, 51003 Tartu
  • Institute of Clinical Medicine
    Faculty phone: 
    +372 737 5323
    Faculty address: 
    L. Puusepa 8, 50406 Tartu
  • Institute of Family Medicine and Public Health
    Faculty phone: 
    +372 737 4190
    Faculty address: 
    Ravila 19, 50411 Tartu
  • Institute of Sport Sciences and Physiotherapy
    Faculty phone: 
    +372 737 5360
    Faculty address: 
    Jakobi 5–205, 51005 Tartu
Faculty of Science and Technology
Faculty phone: 
+372 737 5820
Faculty address: 
Vanemuise 46–208, 51014 Tartu
  • Dean's Office
    Faculty phone: 
    +372 737 5820
    Faculty address: 
    Vanemuise 46–208, 51003 Tartu
  • Institute of Computer Science
    Faculty phone: 
    +372 737 5445
    Faculty address: 
    Narva mnt 18, 51009 Tartu
  • Estonian Marine Institute
    Faculty phone: 
    +372 671 8902
    Faculty address: 
    Mäealuse 14, 12618 Tallinn
  • Institute of Physics
    Faculty address: 
    W. Ostwaldi 1, 50411 Tartu
  • Institute of Chemistry
    Faculty phone: 
    +372 737 5261
    Faculty address: 
    Ravila 14a, 50411 Tartu
  • Institute of Genomics
    Faculty phone: 
    +372 737 4000
    Faculty address: 
    Riia 23b, 51010 Tartu
  • Institute of Mathematics and Statistics
    Faculty phone: 
    +372 737 5860
    Faculty address: 
    Narva mnt 18, 51009 Tartu
  • Institute of Molecular and Cell Biology
    Faculty phone: 
    +372 737 5027
    Faculty address: 
    Riia 23, 23b–134, 51010 Tartu
  • Tartu Observatory
    Faculty phone: 
    +372 737 4510
    Faculty address: 
    Observatooriumi 1, Tõravere, 61602 Tartumaa
  • Institute of Technology
    Faculty phone: 
    +372 737 4800
    Faculty address: 
    Nooruse 1, 50411 Tartu
  • Institute of Ecology and Earth Sciences
    Faculty phone: 
    +372 737 5835
    Faculty address: 
    Vanemuise 46, 51003 Tartu
Institutions
  • Library
    Faculty phone: 
    +372 737 5702
    Faculty address: 
    W. Struve 1, 50091 Tartu
  • Youth Academy
    Faculty phone: 
    +372 737 5581
    Faculty address: 
    Uppsala 10, 51003 Tartu
  • Museum
    Faculty phone: 
    +372 737 5674
    Faculty address: 
    Lossi 25, 51003 Tartu
  • University of Tartu Natural History Museum and Botanical Garden
    Faculty phone: 
    +372 737 6076
    Faculty address: 
    Vanemuise 46, 51003 Tartu
Support Units
  • Administrative Office
    Faculty phone: 
    +372 737 5606
    Faculty address: 
    Ülikooli 18a, 51005 Tartu
  • Centre for Entrepreneurship and Innovation
    Faculty phone: 
    +372 737 4809
    Faculty address: 
    Narva mnt 18, 51009, Tartu
  • University Office in Tallinn
    Faculty phone: 
    +372 737 6600
    Faculty address: 
    Teatri väljak 3, 10143 Tallinn
  • Estates Office
    Faculty phone: 
    +372 737 5137
    Faculty address: 
    Ülikooli 18a, 51005 Tartu
  • Finance Office
    Faculty phone: 
    +372 737 5125
    Faculty address: 
    Jakobi 4, 51005 Tartu
  • Grant Office
    Faculty phone: 
    +372 737 6215
    Faculty address: 
    Raekoja plats 9, 51004 Tartu
  • Information Technology Office
    Faculty phone: 
    +372 737 6000, IT-help: +372 737 5500
    Faculty address: 
    Ülikooli 18a, 51005 Tartu
  • Human Resources Office
    Faculty phone: 
    +372 737 5145
    Faculty address: 
    Ülikooli 18, rooms 302 and 304, 50090 Tartu
  • Internal Audit Office
    Faculty address: 
    Ülikooli 18-244, 51005 Tartu
  • International Cooperation and Protocol Office
    Faculty phone: 
    +372 737 6123
    Faculty address: 
    Ülikooli 18, rooms 104, 301, 305, 50090 Tartu
  • Marketing and Communication Office
    Faculty phone: 
    +372 737 5687
    Faculty address: 
    Ülikooli 18, rooms 102, 104, 209, 210, 50090 Tartu
  • Office of Academic Affairs
    Faculty phone: 
    +372 737 5620
    Faculty address: 
    Ülikooli 18, 50090 Tartu
  • Procurement Office
    Faculty phone: 
    +372 737 6632
    Faculty address: 
    Ülikooli 18a, 51005 Tartu
  • Rector's Strategy Office
    Faculty phone: 
    +372 737 5600
    Faculty address: 
    Ülikooli 18, 50090 Tartu
  • Student Council
    Faculty address: 
    Ülikooli 18b, 51005 Tartu
  • University of Tartu Press
    Faculty phone: 
    +372 737 5945
    Faculty address: 
    W. Struve 1, 50091 Tartu
Other Units
  • University of Tartu Academic Sports Club
    Faculty phone: 
    +372 737 5371
    Faculty address: 
    Ujula 4, 51008 Tartu
  • Tartu Student Village
    Faculty phone: 
    +372 740 9959
    Faculty address: 
    Narva mnt 25, 51013 Tartu
  • Tartu Students’ Club
    Faculty phone: 
    +372 730 2400
    Faculty address: 
    Kalevi 24, 51010 Tartu
  • Tartu University Hospital
    Faculty address: 
    L. Puusepa 1a, 50406 Tartu
  • University of Tartu Foundation
    Faculty phone: 
    +372 737 5852
    Faculty address: 
    Ülikooli 18, 50090 Tartu
  • View all other units

Comparison of coronavirus antibody tests revealed too optimistic claims

Comparison of coronavirus antibody tests revealed too optimistic claims. Pixabay.org

A study by University of Tartu researchers indicates that the sensitivity of tests used to detect viral antibodies in a blood sample may differ significantly. The combination of several tests may give the best result.

At the onset of COVID-19 symptoms, first, the nasopharyngeal swab is taken to verify the presence of the virus. But if the aim is to determine whether an asymptomatic person has been in contact with the virus or, vice versa, to know which acute disease the person recently suffered from, a test detecting antibodies in a blood sample comes helpful.

Antibodies are produced in the human body as a counteraction to viral proteins to prevent the virus from replicating and spreading in the body. Usually, it takes a couple of weeks after infection for the antibodies to emerge. Different parts of the virus induce the development of different antibodies. In the case of coronavirus, for instance, there can be antibodies against the spike protein of the virus, against the proteins of the receptor binding domains as well as against the nucleocapsid.

Different types of antibodies are produced, but the IgG antibodies stay in the body for the longest. “When we ever suffer from a disease, usually the IgG antibodies are the ones to stay in our body,” explained Epp Sepp, Senior Research Fellow in Medical Microbiology at the University of Tartu, one of the authors of the article published in PlosOne.

One use for tests detecting viral antibodies in a blood sample is in large studies trying to ascertain the percentage of the population that has been exposed to the virus. This was also done in spring in the pilot seroepidemiological study in Estonia led by the University of Tartu.
To detect antiviral antibodies, tests are used that detect the presence of antibodies to different proteins or their combinations. There are now hundreds of coronavirus antibody tests, which, unfortunately, are not universally suitable for all patients.

Test sensitivity varies significantly

The study was conducted in cooperation between the University of Tartu, Synlab and Kuressaare Hospital in Saaremaa (Saaremaa is the island in Estonia with the biggest corona outbreak during the first virus wave – editor remark). In the study nine coronavirus antibody tests that were most widely used during the outbreak in spring were analysed. Seven of them were by major producers and two were laboratory tests developed at the University of Tartu by the research group led by Professor Pärt Peterson.

The study involved 97 patients from Saaremaa with a confirmed case of COVID-19. The IgG antibodies to coronavirus were determined by nine tests and the test results were compared based on the patients’ symptoms (cough, headache, tiredness, difficulty breathing, diarrhoea, etc.) and the time between the onset of the disease and the antibody test. The majority of studied patients had COVID-19 symptoms, except for about one fifth of them.

The study revealed that in general, the sensitivity of the tests was lower than the producers had stated. As was expected, the rapid test included in the study at the request of the Health Board had the lowest sensitivity.

In half of the patients, all nine antibody tests gave a positive result. In two patients, none of the tests detected coronavirus antibodies. This implies that antiviral antibodies might not even emerge in some COVID-19 patients. For the rest of the patients, the test results varied. Analysis of the correlation of the results indicated that in some patients, the prevailing antibodies were those against the nucleocapsid while in others antibodies against the spike protein prevailed.

Finding a reliable combination is crucial.

Some tests worked equally well for asymptomatic patients and those with many symptoms. In the case of some tests, the results were highly dependent on the time of taking the sample and the number of symptoms. For instance, for some tests, the positivity rate in asymptomatic COVID-19 cases was about two times lower than in polysymptomatic ones. The best diagnostic sensitivity in detecting antibodies was achieved by combining several antibody tests, for instance, a test detecting antibodies to the spike protein with the test detecting antibodies to the nucleocapsid.

“In the everyday work of Synlab, we are using the Abbott test that is sensitive to antibodies to the nucleocapsid. If that gives a borderline negative result in a patient, we will analyse this sample again using another test sensitive to antibodies to the spike protein. If the result is positive, we will trust that. My experience has shown that antibodies to the nucleocapsid disappear faster and antibodies to the spike protein last for longer,” explained the lead author of the study Paul Naaber, Senior Research Fellow in Medical Microbiology at the University of Tartu.

According to researchers, there is no one perfect test that works well in all cases. To get the most reliable result, the tests may need to be combined. “This is a very important piece of knowledge for planning major seroepidemiological studies. Our analysis showed that had we relied solely on the information written on the package by the producer, the studies in which the tests were used could have led to a completely different result. In spring, only a few published studies had compared tests, so we took it upon ourselves. Objective measurements indicate that test sensitivity may be significantly lower than stated on the package,” Naaber explained.