Serological responses to Anthrax Vaccine Precipitated (AVP) increase with time interval between booster doses

Vaccine. 2022 Sep 21:S0264-410X(22)01045-3. doi: 10.1016/j.vaccine.2022.08.052. Online ahead of print.ABSTRACTWe undertook a Phase 4 clinical trial to assess the effect of time interval between booster doses on serological responses to AVP. The primary objective was to evaluate responses to a single booster dose in two groups of healthy adults who had previously received a complete 4-dose primary course. Group A had received doses on schedule while Group B had not had one for ≥2 years. Secondary objectives were to evaluate the safety and tolerability of AVP booster doses, and to gain information on correlates of protection to aid future anthrax vaccine development. Blood samples were taken on Day 1 before dosing, and on Days 8, 15, 29 and 120, to measure Toxin Neutralisation Assay (TNA) NF50 values and concentrations of IgG antibodies against Protective Antigen (PA), Lethal Factor (LF) and Edema Factor (EF) by ELISA. For each serological parameter, fold changes from baseline following the trial AVP dose were greater in Group B than Group A at every time-point studied. Peak responses correlated positively with time since last AVP dose (highest values being observed after intervals of ≥10 years), and negatively with number of previous doses (highest values occurring in individuals who had received a primary course only). In 2017, having reviewed these results, the Joint Committee on Vaccination and Immunisation (JCVI) updated UK anthrax vaccination guidelines, extending the...
Source: Vaccine - Category: Allergy & Immunology Authors: Source Type: research