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Monitoring the health of individuals and communities could become simpler, cheaper, and more inclusive—through the postal service. Researchers in Sweden used dried blood samples sent in by mail, rather than liquid samples obtained in person, to detect proteins related to COVID-19. Jochen Schwenk, a professor at the KTH Royal Institute of Technology in Stockholm, spoke to Harvard Public Health.

Why study this topic?

We designed this study to test the possibility of doing a health-related investigation outside of clinical settings with the general population. When COVID-19 came in 2020, PCR tests, which look for the virus’s genetic material, were not yet widely available, and serology tests could only inform about previous infections. Clinical studies were hard to do at the beginning of the pandemic, and nobody wanted to risk exposure by giving a blood sample. Researchers were dependent on the samples available from hospitals to learn how patients responded to the virus; however, most people did not need hospital care.

What did you find?

We found that you can measure antibodies and clinically relevant proteins in dried blood samples. We can use different technologies to investigate the molecules on these dry blood-spot cards. Self-sampling is more cost-effective because you don’t have to book an appointment to collect a blood sample. This also frees up clinical staff time.

What would you like to see happen based on the study’s results?

We’d like to see other uses of this concept. When a patient is discharged from the hospital, you could give them mail-in blood sample cards to follow their recovery or medication response. From random samples, you could study the social and psychological aspects of participating in health surveys. I want to see more of us get interested in examining proteins on a population scale to analyze public health.

Leah Samuel

(Study in Communications Medicine, April 2024)

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