Vaccine Evidence Compendium

Hexavalent vaccines

Benefits of the intervention

Serogroup or serotype coverage by vaccines considered (for serogroup- or serotype-specific vaccines)

Serogrouping is not relevant to the efficacy or effectiveness of diphtheria, tetanus, pertussis, or hepatitis B vaccines.

There are six serotypes of Haemophilus influenzae (types a to f) of which type b was the most common cause of severe disease in children. Disease due to other serotypes and non-typeable Haemophilus influenzae can cause disease, though they are not a common cause of severe diseases in children. Hexavalent vaccines include only the Hib component and do not protect against disease caused by other H. influenzae serotypes or non-typeable strains.,

Poliovirus has three serotypes: types 1, 2, and 3. Immunity to one serotype does not confer protection against the others, IPV-containing hexavalent vaccines include antigens against all three poliovirus serotypes.,

Efficacy and effectiveness estimates (e.g. against infection, disease, hospitalization, death), including in different populations

Clinical studies show that licensed hexa-aP vaccines demonstrate robust immune responses against all six targeted diseases, , , , , , , , , , , ,  :

The hexa-wP vaccine was licensed based on demonstration of non-inferiority in the antibody responses to the existing pentavalent (containing aP) and inactivated poliovirus vaccines (IPV). Empirical data on the efficacy of this combination vaccine against each of the targeted diseases is limited.

Evidence suggests that whole-cell pertussis (wP) vaccines have a stronger effect on transmission than aP containing vaccines. This may be relevant in terms of the number of booster doses required.

Seroprotective levels of antibodies to all three poliovirus serotypes are induced following three doses of both hexa-aP  and hexa-wP  when administered in a 6, 10, and 14 weeks schedule.

IPV induces limited intestinal mucosal immunity in previously unvaccinated individuals. However, a dose of IPV can enhance mucosal protection in individuals previously exposed to polioviruses or who have received OPV.

Duration of protection and waning of immunity in general and risk groups

Duration of protection varies by vaccine antigen, vaccination schedule and use of booster doses. Long-term persistence data are available for the individual vaccine components and for some hexavalent vaccine schedules, although the extent of evidence differs by antigen and vaccine formulation., , , , , , , , , , , , ,

Diphtheria - Data on the duration of seroprotection from two large representative population studies from the Netherlands, using a complete 3-dose primary series plus 3-dose booster series prior to adolescence, indicate that this schedule results in very high seroprevalence above the threshold for basic protection (≥0.01 IU/mL) up to 39 years of age and potentially longer., ,

Tetanus - Data from serological studies suggest that a primary series of three tetanus toxoid containing vaccine doses in infancy plus a booster during the second year of life will provide three to five years of protection. A further booster dose (e.g. in early childhood) provides protection into adolescence, and another booster during adolescence induces immunity that lasts through much of adulthood, including protection for women of reproductive age., ,

Pertussis - Whereas little is known about the duration of protection following pertussis vaccination in LMICs, several studies in HICs that use hexa-aP vaccines show that protection wanes after 4-12 years.,  Data for for hexa-wP is limited, evidence from animal models and mathematical modelling suggests that aP containing vaccines may have shorter duration of protection compared to wP containing vaccines.

Hepatitis B - In a study in Alaska, USA, a 3-dose vaccination schedule prevented all clinically apparent and chronic HepB infection for at least 30 years., , ,

Hib - Although there is some evidence of a decrease over time in the proportion of Hib vaccine recipients with antibody levels higher than the set thresholds, there is only limited evidence to suggest that this decline is associated with an increase in clinical disease.,

Poliomyelitis - Vaccination induces long-term protection against paralytic disease. For IPV, evidence from high-income countries indicates that circulating antibodies persist for decades and possibly for life, including detection 18 years after infant vaccination plus a childhood booster.

Introduction of a hexavalent vaccine in the infant primary series should be considered within the broader national schedule, including booster-dose recommendations for the relevant antigens.

Sources
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