The bacterial infection phenotype of MyD88 or IRAK-4 deficiency is clearly recessive (Picard et al., 2010), but we analyzed possible co-dominance for the COVID-19 phenotype in 20 unvaccinated household relatives heterozygous for MYD88 or IRAK4 (mean age: 32.4 yr, SD: 12.3 yr, range: 10–52 yr). This evidence concerns the gene MYD88 and bacterial infectious disease.