Primeboost

Prime-boost, sometimes written as prime-boost or primeboost, is a vaccination strategy in which an initial immunization (the prime) is followed by one or more subsequent immunizations (the boosts) to enhance and extend protective immunity. The approach seeks to increase the magnitude, breadth, and durability of both antibody and cellular responses against the target antigen beyond what a single dose can achieve.

Two common designs are used. In homologous prime-boost, the same vaccine formulation is given for both prime and boost. In heterologous prime-boost, different vaccine platforms are used for prime and boost, such as a DNA or viral-vector prime followed by a protein subunit or another vector boost. Heterologous regimens can help overcome issues like vector-specific immunity that may limit responses to repeated doses.

Applications span vaccines and cancer immunotherapy. Prime-boost strategies are particularly important in challenging pathogens, including HIV, malaria, and tuberculosis, and have been employed in several COVID-19 vaccine regimens. Common combinations include DNA priming with viral-vector or protein boosts, and vector-based priming with protein or subunit boosts. The approach is also used to tailor immune responses, targeting both humoral and cellular arms.

Design considerations and challenges include choosing appropriate intervals between doses, antigen dose and formulation, and the use of adjuvants to optimize responses. Safety, tolerability, and manufacturing complexity must be balanced against immunogenicity gains. Pre-existing immunity to vaccine vectors and logistical factors can influence the success of prime-boost strategies.