Reactogenicity to primary and repeated vaccination with influenza split virus vaccine

Area of Science:

• Immunology
• Vaccinology
• Public Health

Background:

• Influenza vaccines are crucial for preventing seasonal flu outbreaks.
• Understanding vaccine antigen concentration's impact on side effects is important for public health strategies.
• Previous vaccination history may influence individual responses to influenza vaccines.

Purpose of the Study:

• To compare the local and general reactions to two different antigen concentrations of split, adsorbed influenza vaccines.
• To assess the influence of prior influenza vaccinations on vaccine-induced side effects.
• To evaluate the safety profile of high-purity split, adsorbed influenza vaccines.

Main Methods:

• A study involving 1,111 adult participants of both sexes.
• Administration of influenza vaccines with two distinct antigen concentrations (commercial production).
• Observation and recording of local and general reactions in participants with up to five previous vaccinations.

Main Results:

• No significant difference in local or general reactions between primo-vaccinees and boostered individuals.
• Increasing rates of previous vaccinations did not correlate with increased adverse event rates.
• The group receiving higher antigen concentration vaccine exhibited a lower incidence of side effects compared to the lower concentration group.

Conclusions:

• Higher antigen concentration of split, adsorbed influenza vaccines may be associated with a reduced rate of side effects.
• Split, adsorbed influenza vaccines of high purity may not induce sensitization, even with multiple prior vaccinations.
• These findings support the use of optimized influenza vaccine formulations for improved safety and tolerability.