Older adult populations are underrepresented in clinical trials, with poor health status or accessibility issues serving as barriers. Those living in rural or remote communities are less likely to participate, and are unfairly excluded given their proximity from central testing facilities. So too, despite making up upwards of 30% of the American population, people of color represent less than a quarter of patients in clinical trials.
Intensive time and resources are dedicated to the development of novel medications and therapeutics, and yet, their clinical efficacy is only understood in the context of a small, non-representative subset of our population.
Over 40% of Canadians with a chronic hepatitis C infection are undiagnosed. For people living with HIV, the number is close to 15%. Testing is a crucial link to access of prevention, care, and treatment services, but barriers to diagnosis persist in communities across Canada and the entire world.
Immunology research and public health surveillance and diagnostics are not immune to inequity.
The global vaccination effort against SARS-CoV-2 marked one of the most significant preventative public health campaigns to take place since the Global Polio Eradication Initiative, which shed light on the importance of measuring immunogenicity at the population-level. This comes down to the fact that the humoral immune response may be distinct across different ages, sexes, or even vaccine doses received, necessitating population-level information to properly formulate vaccine recommendations and design health policy.
If we want to truly understand how all individuals respond to a vaccine, and if we want to truly understand who has been impacted by an outbreak (and whether those in particular communities may have in fact been exposed to a pathogen or previously infected), we need to leverage a sample type that will allow for more robust and accessible collection.
The evaluation of immunogenicity against particular antigens, whether they have been introduced via vaccination or infection itself (for the purposes of vaccine development or public health surveillance), is dependent upon serological analysis of whole blood samples. Traditionally, this may be collected in large volumes via venipuncture. Samples may also be collected from capillary beds, though a comparatively smaller volume may be yielded. These samples are known as dried blood spots (DBS).
DBS function as a reliable and viable alternative to venous blood sampling. Individuals may simply prick their finger with a lancet and spot their blood onto filter-paper-based cards, independent of trained phlebotomists. The cards may remain at ambient temperatures for up to two weeks, eliminating the need for cold-chain transport. They may be transported to centralized testing facilities and laboratories via typical postal systems, without specialized shipping containers. In the lab, the dried blood spots may be rehydrated, and subsequently used in assays in the same manner as venous blood samples would.
DBS is useful for those who may be needle averse or have poor venous access (such as young infants), and it is clearly an attractive option in low-resource and remote settings, allowing individuals who otherwise cannot access labs for a blood draw to easily participate in research.
A number of large-scale studies have utilized DBS to evaluate the scope of viral infections at the population-level. So too, ongoing vaccine evaluation efforts are incorporating DBS into their participant cohorts, thereby expanding the base of research participation.
If we want to “Jennerate” population-level immunity against infectious diseases, maybe we should more readily make use of a sample type that facilitates the diagnosis of and an understanding of the immune response in all communities (however near or far).
References
- Viegas, N. 2024. Using dried blood spots to measure spike-specific SARS-CoV-2 IgG concentration and avidity. Honours Thesis.
- https://pubmed.ncbi.nlm.nih.gov/35266818/
- https://pubmed.ncbi.nlm.nih.gov/26157353/
- https://pubmed.ncbi.nlm.nih.gov/36596443/
- https://pubmed.ncbi.nlm.nih.gov/22244848/
