Diphtheria booster vaccination: one or two injections?

Area of Science:

• Immunology
• Vaccinology
• Public Health

Background:

• Diphtheria immunity wanes over time, necessitating booster vaccinations.
• Assessing the immunogenicity of diphtheria booster vaccines in adults with remote vaccination histories is crucial for maintaining population immunity.

Purpose of the Study:

• To compare the immunogenicity and tolerance of a single versus two diphtheria booster vaccinations.
• To evaluate the serological response in adults whose last diphtheria vaccination was over 10 years prior.

Main Methods:

• Prospective, controlled, randomized, multicenter study design.
• 415 subjects received one booster, 203 received two boosters (at day 0 and day 28).
• Diphtheria antitoxin concentrations were measured before and after vaccination (days 28 and 56).

Main Results:

• Both single and double booster regimens achieved high seroprotection rates (≥0.1 IU/ml), with 95.4% and 97.5% of subjects reaching protective levels after one and two boosters, respectively.
• Geometric mean diphtheria antitoxin concentrations were 2.354 IU/ml after the first booster and 2.238 IU/ml after the second.
• A second booster administered 4 weeks after the first did not demonstrate a significant additional serological effect.

Conclusions:

• A single diphtheria booster vaccination is highly effective in restoring protective immunity in adults with waning immunity.
• While a second booster did not show a clear added benefit, both schedules resulted in high seroprotection rates.
• Further research may explore optimal intervals for diphtheria booster vaccinations in adults.