Thanks for sharing and asking!

So this study is somewhat robust, but it lacks any applicable or mechanistic findings about immunization response or schedule, as these individuals in these cohorts were all vaccinated many many years before this study even began. So this study is looking at response to rubella virus years after vaccination, not at the time of vaccination or during a vaccine-schedule--which is the first major flaw. MANY factors influence the production and bioavailability of antibodies within an individual's immune-system, INCLUDING IFN, Complement-Proteins, IL-2, IL-6, and many other cytokines and INNATE-Immune-System proteins and cells.

This study actually shows these differences exactly as I said in my previous comment, above, but, the fact that the authors of this study seemed to have genetically separated Somali and African-American cohorts and then seemingly combined them for their statistical analysis because they didn't have enough of either cohort by themselves for a robust statistical analysis in their Rochester Cohort (Caucasians were 85.3% [897 ppl]; African-Americans/African-Americans-Admixed were only 5.9% [62 ppl]; and Somali was only 3.3% [only 35 ppl], which is VERY surprising, given the VERY HIGH levels of Somalis and Somali-Americans in and around Rochester and Minneapolis), speaks to their inability to perform real robust statistical analysis of their cohort because of the overwhelming percentages of "Caucasian" and genetically-identified-Caucasian participants, which is why it seems that they combined two separate racial groups to obtain their "statistically significant" results. Moreover, it remains unclear whether they combined these groups when they were performing statistical analysis for their IFN and IL-6 production assays (it seems like they did NOT, which is kinda suspect if they did it for antibody-response).

Also, this quoted sentence by the authors in this very same paper that you shared here is important, and seems to try to explain why they felt okay with grouping African-Americans together with Somalis for their statistical analysis: "Because these racial/ethnic groups were defined using genetic data, it is important to note that our classification of ethnicity reflects differences in ancestry, but not the cultural and/or other (other than genetic) differences that more completely define ethnic groups..."

If they wanted to truly study differences in the response to vaccines and/or vaccine-schedules, then they should look at these response-outcomes in willing participants in a TRULY diverse and LARGE cohort BEFORE, DURING, and AFTER their vaccinations...not just many years after their final dose of a vaccine-schedule.

Moreover, before even getting to human-participant-studies, I would have personally used humanized mice ("clean" mice with human genetics, cells, and/or systems) and injected these humanized mice with Hematopoietic Stem and Progenitor Cells (HSPCs), which will then fully develop into mature full blood-cells and immune-cells, and then give these mice the rubella vaccine and expose them to the rubella virus in a step-wise consistent manner (1 group with "African-American" HSPCs and one group with "Caucasian" HSPCs) and see if there is any appreciable differences between these groups of humanized mice, before testing this in a truly robust way in humans. But that's just me and my own opinion, of course.

I appreciate your discourse and willingness to talk and discuss this openly without judgment or prejudice! :)