Recombinant HA-based vaccine outperforms split and subunit vaccines in elicitation of influenza-specific CD4 T cells and CD4 T cell-dependent antibody responses in humans.

Although traditional egg-based inactivated influenza vaccines can protect against infection, there have been significant efforts to develop improved formats to overcome disadvantages of this platform. Here, we have assessed human CD4 T cell responses to a traditional egg-based influenza vaccine with recently available cell-derived vaccines and recombinant baculovirus-derived vaccines. Adults were administered either egg-derived Fluzone®, mammalian cell-derived Flucelvax® or recombinant HA (Flublok®). CD4 T cell responses to each HA protein were assessed by cytokine EliSpot and intracellular staining assays. The specificity and magnitude of antibody responses were quantified by ELISA and HAI assays. By all criteria, Flublok vaccine exhibited superior performance in eliciting both CD4 T cell responses and HA-specific antibody responses, whether measured by mean response magnitude or percent of responders. Although the mechanism(s) underlying this advantage is not yet clear, it is likely that both qualitative and quantitative features of the vaccines impact the response.

How to: implement procalcitonin testing in my practice.

BACKGROUND: Adding procalcitonin (PCT) to antibiotic stewardship algorithms may improve antibiotic use. However, PCT protocols need to be adapted to clinical settings and patient populations. OBJECTIVES: To review PCT use in different medical settings and patient populations. SOURCES: Most recent trials and meta-analyses investigating PCT for antibiotic stewardship were reviewed. CONTENT: Several trials found PCT-guided antibiotic stewardship to reduce antibiotic exposure and associated side-effects among patients with respiratory infection and sepsis. Decisions regarding antibiotic use in an individual patient are complex and should be based on the pre-test probability for bacterial infection, the severity of presentation and the results of PCT. In the context of a low pre-test probability for bacterial infections and a low-risk patient, a low PCT level helps to rule out bacterial infection and empiric antibiotic therapy can be avoided. In the context of a high pre-test probability for bacterial infections and/or a high-risk patient with sepsis, monitoring of PCT over time helps to track the resolution of infection and decisions regarding early stop of antibiotic treatment. Although these concepts have been successful in several respiratory infection and sepsis trials, some studies failed to show an added benefit of PCT due to factors such as low protocol adherence and relying on single rather than repeat PCT measurements. IMPLICATION: As an adjunct to other clinical and laboratory parameters, PCT provides information about risk for bacterial infection and resolution of infection, and improves antibiotic stewardship decisions, thereby offering more individualized treatment courses with overall reduced antibiotic exposure.