Raw metagenomic sequences of the he WELCOME (WEilL COrnell Medicine Employees) (protocol number IRB# 20-04021831) trial conducted at Weill Cornell Medicine (WCM) and New York Presbyterian Hospital (NYP). WELCOME

Here we show in three independent cohorts of health care workers (HCW) or cancer patients across three different vaccine formulations (mRNA, dendritic cells or tumor peptides respectively) that 20-25% of vaccinees fail to mount protective Th1/Tc1 immune responses directed against the vaccine antigens. The lack of RBD-S1-specific T cell immune responses was not attributable to HLA genotypes in two consecutive groups of HCW immunized with COVID-19 vaccines but was strongly associated with gut dysbiosis. We extended the exemplification of a protective role of a healthy gut microbiota spearheaded by Lachnospiraceae and Ruminococcaceae family members in the immunogenic capacity of vaccines in patients with melanoma and lung cancer.