As per the New York Times:

Moderna’s problem seemed fitting for late summer 2020, when the United States was reeling from not just a pandemic but unrest over racial injustice. Dr. Slaoui informed Mr. Bancel that Moderna had not recruited enough minority candidates into its vaccine trials. If it could not prove its vaccine worked well for Black and Hispanic Americans, who have been disproportionately affected by the pandemic, it would not make it over the finish line.

Are there vaccines which work for humans of one ethnicity, but have a lesser efficacy for humans of a different efficacy? If not, why would medical authorities be concerned about recruiting humans of different ethnicities for the trial?


2 Answers 2


Some differences have been observed in certain studies, although most reviews nowadays seem focused on the genetics angle in variations to vaccine response. One such (2015) review cites (somewhat in passing) as evidence for known variation in ethnically linked response a study in Taiwan that found response variation for some vaccines but not for others (the groups involved being aboriginals vs Han Chinese):

children whose parents were both aborigines had lower anti-HBs [hepatitis B] mean titer than did children whose parents were both ethnic Han Chinese. Children of mixed parental origins had intermediate mean titer of anti-HBs. Serologic responses to Japanese encephalitis virus and diphtheria vaccines did not show such correlation with ethnic groups, indicating that the determinant for HBV hyporesponsiveness among the aboriginal children is distinct from that of other childhood vaccines. It was therefore concluded that host factors pertaining to ethnic origin might be responsible for the hyporesponsiveness to HBV vaccine in the aboriginal populations

Such differences in the immediately quantifiable immune response were observed in other studies, e.g., one in the US (on response to rubella vaccine in African-Americans vs others):

individuals of African descent have significantly higher rubella-specific neutralizing antibody levels compared to individuals of European descent and/or Hispanic ethnicity

Our study provides consistent evidence for racial/ethnic differences in humoral immune response following rubella vaccination.

However, in the conclusion section, the authors note that some caution may be required in interpreting such results from the angle of clinical relevance:

although it would be difficult to interpret our findings [...] in terms of possible protection from infection [... we] speculate that the higher neutralizing antibody levels observed for African-Americans (compared to Caucasians and/or Hispanics) in our study may potentially denote genetic and racial differences in the long-term immunity and protection following vaccination

A 2007 review (also on genetic variations) mentions two studies for observed ethnic differences in vaccine response; both studies found differences in the response to measles vaccine one on Bedouin vs Jewish Israelis response (to the MMR combo):

Seroconversion to measles was 99% in Bedouin and 79% in Jewish children (P < 0.01), and that to mumps and rubella was 92 to 100% in both groups [For the latter two presumably not a statistically significant difference; P not reported in the abstract.] Measles neutralizing antibody titers were higher in Bedouin (333 +/- 39 mIU/ml) than Jewish (122 +/- 60 mIU/ml) children (P < 0.002). [...] It is not known whether genetic differences or environmental exposure accounts for these differences.

the other on Inuit/Inuit vs Caucasian:

Native (Innu and Inuit) schoolchildren (n = 253) had a significantly higher seropositive rate (83%) after a single dose of measles vaccine compared to Caucasian (n = 353) children (76%; p = 0.025),

One interesting result to highlight perhaps is that a 2016 study on influenza vaccine (components) found that the ethnic/race differences were mainly found in the younger groups:

Race-related differences were caused by samples from younger African Americans, while results obtained with samples of aged African Americans were similar to those of aged Caucasians.


Are there vaccines which work for humans of one ethnicity, but have a lesser efficacy for humans of a different efficacy?

Yes, e.g. influenza vaccine {1,2}. One reason is that some genes influence the anti-influenza antibody response, and some of these genes are correlated to the ethnicities. E.g., from {2}:

In addition, we analyzed ethnically diverse individuals within the 1000 genomes project and discovered marked variations in F- and L- genotypes and CN among the various ethnic groups that may impact HV1-69-sBnAb responses. These results have immediate implications for understanding HV1-69-sBnAb responses at the individual and population level and for the design and implementation of “universal” influenza vaccine.


  • {1} Watson, Corey T., Jacob Glanville, and Wayne A. Marasco. "The individual and population genetics of antibody immunity." Trends in immunology 38, no. 7 (2017): 459-470. https://doi.org/10.1016/j.it.2017.04.003
  • {2} Avnir, Yuval, Corey T. Watson, Jacob Glanville, Eric C. Peterson, Aimee S. Tallarico, Andrew S. Bennett, Kun Qin et al. "IGHV1-69 polymorphism modulates anti-influenza antibody repertoires, correlates with IGHV utilization shifts and varies by ethnicity." Scientific Reports 6 (2016). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4754645/
  • This answer does not contain any original content, instead only consisting of quotes even if these are referenced, contrary to meta.stackexchange.com/help/referencing "Do not copy the complete text of external sources; instead, use their words and ideas to support your own." (emphasis mine) It also doesn't really answer the question asked.
    – Bryan Krause
    Commented Dec 3, 2020 at 23:57
  • @BryanKrause That's because the answer is simply yes. This really answers the question asked. Commented Dec 3, 2020 at 23:58
  • 2
    This doesn't answer the question asked and it's a link-only answer.
    – Carey Gregory
    Commented Dec 4, 2020 at 5:06
  • @CareyGregory The question is "Are there vaccines which work for humans of one ethnicity, but have a lesser efficacy for humans of a different efficacy?". The answer is "Yes, e.g. influenza vaccine {1,2}. From {2}:". What else do you want me to say? Commented Dec 4, 2020 at 5:12
  • You don't answer the question in your own words, and I don't see an answer in your quote either. The only answer here is in the links, and that makes it a link-only answer. We're not going to have this debate yet again. Please fix it. I know you know how.
    – Carey Gregory
    Commented Dec 4, 2020 at 6:33

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