The claim that obesity leads to less effective vaccine responses is contested in the literature; while several studies and reviews indicate that high body mass index impairs immunogenicity and antibody production (particularly in males), other clinical and epidemiological analyses find no significant reduction in real-world vaccine effectiveness or seroprotection rates.
Obesity is associated with impaired immunogenicity for some vaccines, though findings are mixed regarding real-world effectiveness.
Weighing the retrieved literature reveals a split. Papers 3, 4, 6, and 10 support the premise that obesity negatively impacts vaccine-induced immunity, antibody titers, or seroconversion (often with sex-specific nuances). Conversely, Papers 7 and 9 find no statistically significant impairment of seroprotection or clinical vaccine effectiveness among individuals with elevated BMI. Because there are valid sources on both sides showing negative immunological impacts versus preserved clinical effectiveness/seroprotection, the verdict is CONTESTED.