ABSTRACT
Objectives: At the beginning of the pandemic, it was believed that severe SARS-CoV2 infection would induce lifelong immunity and that reinfections would be unlikely. However, several cases of reinfection were documented in previously infected patient and the waning humoral immunity has raised significant concerns. Accordingly, long-term and durable vaccineinduce antibody protection against infection have also become a challenge, as several breakthroughs of COVID-19 have been identified in individuals partially or fully vaccinated. This study describes the incidence, the characteristics of severe COVID-19 infections requiring ECMO occurred after vaccination and the presence of side effects related to the vaccine. Method(s): EuroECMO COVID is a prospective, multicenter, observational study, developed by the EuroELSO, based on data from patients aged >=16 years who received ECMO support for refractory COVID-19 during the pandemic in 204 centers. The analysis investigates the survival of vaccinated patient, the associations between management-related variables, the incidence of vaccination during the different pandemic phases, the type of vaccines and the possible side effects. Result(s): Immunosuppressed patients are susceptible to reinfection even after being naturally infected or receiving a full vaccination. Ineffective antibody production, due to relatively ineffective vaccines, inadequate number of doses or the time after vaccination are involved in the pathogenesis of postvaccination infections. This population was found to have a partial immunity due to an inadequate number of doses and an overlapped time from vaccination and SARS-CoV2 incubation with PCR results after being vaccinated. Several manifestations of SARS-CoV2 infection are similar to vaccine-induce side effects and mild symptoms can be presented both as an adverse reaction after vaccination and a result of infection. In this subgroup no side effects were attributable to the vaccine. Conclusion(s): Vaccination does not entirely prevent SARS-CoV2 but will lead to less morbidity and mortality, as demonstrated by less need of ICU and ECMO care. In addition, the partial immunity for inadequate doses of vaccine or through the evolution of new variants demonstrated the importance of further analysis to differentiate the possible causes of waning humoral immunity.