Blood and saliva SARS-CoV-2 antibody levels in self-collected dried spot samples

Laura Lahdentausta (Corresponding Author), Anne Kivimäki, Lotta Oksanen, Marika Tallgren, Sampo Oksanen, Enni Sanmark, Aino Salminen, Ahmed Geneid, Mikko Sairanen, Susanna Paju, Kalle Saksela, Pirkko Pussinen, Milla Pietiäinen

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)


We examined the usefulness of dried spot blood and saliva samples in SARS-CoV-2 antibody analyses. We analyzed 1231 self-collected dried spot blood and saliva samples from healthcare workers. Participants filled in a questionnaire on their COVID-19 exposures, infections, and vaccinations. Anti-SARS-CoV-2 IgG, IgA, and IgM levels were determined from both samples using the GSP/DELFIA method. The level of exposure was the strongest determinant of all blood antibody classes and saliva IgG, increasing as follows: (1) no exposure (healthy, non-vaccinated), (2) exposed, (3) former COVID-19 infection, (4) one vaccination, (5) two vaccinations, and (6) vaccination and former infection. While the blood IgG assay had a 99.5% sensitivity and 75.3% specificity to distinguish participants with two vaccinations from all other types of exposure, the corresponding percentages for saliva IgG were 85.3% and 65.7%. Both blood and saliva IgG-seropositivity proportions followed similar trends to the exposures reported in the questionnaires. Self-collected dry blood and saliva spot samples combined with the GSP/DELFIA technique comprise a valuable tool to investigate an individual’s immune response to SARS-CoV-2 exposure or vaccination. Saliva IgG has high potential to monitor vaccination response wane, since the sample is non-invasive and easy to collect.

Original languageEnglish
Pages (from-to)173-183
Number of pages11
JournalMedical Microbiology and Immunology
Issue number4
Publication statusPublished - Aug 2022
MoE publication typeA1 Journal article-refereed


  • Antibody
  • Blood
  • COVID-19
  • Dried spot sample
  • Exposure
  • Saliva
  • SARS-CoV-2
  • Vaccination
  • Humans
  • Immunoglobulin G
  • Antibodies, Viral
  • COVID-19/diagnosis


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