Dried samples of saliva and fingertip blood are useful in monitoring responses to coronavirus vaccines

Based on an antibody study, dried samples of easily self-collected saliva and of blood drawn from the fingertip could be useful for monitoring people’s immune responses to vaccination.

In a study by the University of Helsinki and HUS Helsinki University Hospital, the levels of antibodies associated with the SARS-CoV-2 virus were analysed in more than 1,200 employees in the social welfare and healthcare sector to determine whether there were differences in different antibody classes according to viral exposure. Dried saliva and blood samples collected between January and March 2021 were utilised in the study. The exposure and background data were collected using a questionnaire.

Based on the results, immunoglobulin G (IgG) has a 99.5% sensitivity and 75.3% specificity to distinguish people with two vaccinations from non-exposed and exposed individuals, individuals with previous Covid-19 infection, and those with one vaccination. IgG measured from saliva also had an 85.3% sensitivity and 65.7% specificity in distinguishing people with two vaccinations from the other groups.

The results of the study have been published in the Medical Microbiology and Immunology journal.

Dentists had the lowest amount of antibodies against the virus

The study attested to the exposure of social welfare and healthcare employees to coronavirus, visible in the results as elevated antibody levels. A total of 47.5% of nurses and 47.7% of doctors were seropositive due to either a previous infection, vaccination or exposure, whereas only 8.7% of dentists had been exposed to the virus. In addition to dentists, the lowest antibody levels were observed in administrative staff and social workers.

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