The "identikit" of subject with obesity and COVID-19 vaccine breakthrough

The mRNA coronavirus disease 2019 (COVID-19) vaccines were highly effective in the prevention of symptomatic COVID-19, hospitalization, severe disease, and death. However, a minority of vaccinated individuals might become infected and experience significant morbidity. Risk factors of COVID-19 vaccine breakthrough in obesity have not been elucidated. Thus, we aimed to portray the subjects with obesity developing COVID-19 vaccine breakthrough despite vaccination. Coronavirus 2019 (COVID-19) mRNA vaccines have been highly effective in preventing symptomatic COVID-19, hospitalization, severe illness and death. However, a minority of vaccinated individuals may become infected and experience considerable morbidity. The risk factors for COVID-19 vaccine breakthrough in obesity have not been elucidated. Therefore, we aimed to depict individuals with obesity who develop COVID-19 vaccine breakthrough despite vaccination. An online questionnaire was distributed to respondents via a snowball sampling method among subjects with obesity belonging to Italian Associations for people living with obesity aged 18 years and above. Two hundred and thirty-five respondents (44.5±14 years; BMI: 33.3±7.2 kg/m²) were included in the study. COVID-19 vaccine breakthrough was noted in 34 % of respondents. A higher prevalence of grade III obesity was detected in subjects with COVID-19 vaccine breakthrough compared to subjects that did not (27.5 % vs 13.5 %; p=0.014). In addition, a significant lower prevalence of respondents that completed third dose were found in respondents with COVID-19 vaccine breakthrough compared with respondents that did not develop it (33.8 % vs 72.9 %; p<0.001). After stratifying respondents with COVID-19 vaccine breakthrough according to the completed doses of vaccine, we found that, although no differences were detected in terms of clinical manifestations of COVID-19, there was a significant higher prevalence of type 2 diabetes and hypertension in respondents that completed third doses compared to respondents that completed first and second doses. In conclusion, COVID-19 vaccine breakthrough was more common in subjects with grade III obesity. The presence of type 2 diabetes and hypertension could counteract the immune potentiating effects of vaccine booster against COVID-19.