Reduced-antigen, combined diphtheria, tetanus, and acellular pertussis vaccine, adsorbed (boostrix(®)): a guide to its use as a single-dose booster immunization against pertussis.

Reduced-antigen, combined diphtheria, tetanus, and three-component acellular pertussis vaccine (Tdap; Boostrix(®)) is indicated for booster vaccination against diphtheria, tetanus, and pertussis. In clinical trials, a single booster dose of Tdap induced high seroprotective levels of antibodies to its three component acellular pertussis antigens in virtually all children and adolescents, and in a high proportion of adults and elderly individuals, at ≈1 month post-vaccination, irrespective of their vaccination history. Seropositivity rates for antibodies against pertussis toxin had begun to decline by 5 years after a booster dose of Tdap in adolescents/adults, with a subsequent booster dose 10 years later generally as immunogenic and as well tolerated as the initial booster. Tdap was safe and well tolerated in all age groups.

Vaccination with 3-dose paediatric rotavirus vaccine (RotaTeq®): impact on the timeliness of uptake of the primary course of DTPa vaccine.

BACKGROUND: In countries like Australia where high coverage rates of early childhood vaccines has been achieved, ensuring timely vaccination is the next challenge--particularly where multiple doses are required for protection (e.g. DTPa vaccine). Since July 2007, for the first time, the Australian childhood vaccination schedule has included a vaccine (rotavirus vaccine) that must be administered within strict dosing windows. AIM: To determine whether the introduction of a 3-dose rotavirus vaccine (RotaTeq® into the national childhood immunisation program in Victoria, Australia, had an impact on the timeliness of the primary course of DTPa vaccine that is also scheduled at the same ages (2, 4 and 6 months). STUDY: We studied de-identified data of >17,000 children residing in four large and culturally diverse localities in the Eastern Region of Melbourne, Victoria who were born prior to or after the introduction of RotaTeq® into the National Immunisation Program schedule. Timeliness was defined as the proportion of children who received a particular dose of DTPa vaccine within the dosing window for the equivalent dose of RotaTeq®. We were particularly interested in any change in the timeliness of dose 3 of DTPa vaccine. RESULTS: Before the introduction of RotaTeq®, timely uptake of doses 1 and 2 of DTPa vaccine was high (93-97%). However, timeliness of the 3rd dose was markedly lower, dropping to 80% in one locality. In the post-RotaTeq® cohort, rates of timely uptake for doses 1 and 2 of DTPa vaccine remained high (97-99%). However, for DTPa vaccine dose 3, there was a clear trend toward improved timeliness--increasing by 5 to up to 12 percentage points compared with the pre-RotaTeq® cohort. CONCLUSION: Inclusion in the national immunisation schedule of the 3-dose vaccine RotaTeq® that has strict dosing windows encourages parents to present in a timely fashion for their child's vaccination, which in turn may drive an improvement in timeliness of other concurrently scheduled vaccines (e.g. DTPa). Introduction of government-funded RotaTeq® may improve the uptake of the crucial 3rd dose of DTPa vaccine, where traditionally the greatest delays are noted.

Mercury levels in newborns and infants after receipt of thimerosal-containing vaccines.

OBJECTIVES: Thimerosal is a mercurial preservative that was widely used in multidose vaccine vials in the United States and Europe until 2001 and continues to be used in many countries throughout the world. We conducted a pharmacokinetic study to assess blood levels and elimination of ethyl mercury after vaccination of infants with thimerosal-containing vaccines. METHODS: Blood, stool, and urine samples were obtained before vaccination and 12 hours to 30 days after vaccination from 216 healthy children: 72 newborns (group 1), 72 infants aged 2 months (group 2), and 72 infants aged 6 months (group 3). Total mercury levels were measured by atomic absorption. Blood mercury pharmacokinetics were calculated by pooling the data on the group and were based on a 1-compartment first-order pharmacokinetics model. RESULTS: For groups 1, 2, and 3, respectively, (1) mean +/- SD weights were 3.4 +/- 0.4, 5.1 +/- 0.6, and 7.7 +/- 1.1 kg; (2) maximal mean +/- SD blood mercury levels were 5.0 +/- 1.3, 3.6 +/- 1.5, and 2.8 +/- 0.9 ng/mL occurring at 0.5 to 1 day after vaccination; (3) maximal mean +/- SD stool mercury levels were 19.1 +/- 11.8, 37.0 +/- 27.4, and 44.3 +/- 23.9 ng/g occurring on day 5 after vaccination for all groups; and (4) urine mercury levels were mostly nondetectable. The blood mercury half-life was calculated to be 3.7 days and returned to prevaccination levels by day 30. CONCLUSIONS: The blood half-life of intramuscular ethyl mercury from thimerosal in vaccines in infants is substantially shorter than that of oral methyl mercury in adults. Increased mercury levels were detected in stools after vaccination, suggesting that the gastrointestinal tract is involved in ethyl mercury elimination. Because of the differing pharmacokinetics of ethyl and methyl mercury, exposure guidelines based on oral methyl mercury in adults may not be accurate for risk assessments in children who receive thimerosal-containing vaccines.

Boostrix (GlaxoSmithKline).

GlaxoSmithKline plc has developed and launched Boostrix, a subunit vaccine for use in adolescents and adults as a booster immunization against diphtheria, tetanus and pertussis (DTPa) infections.

Assessing equivalence: an alternative to the use of difference tests for measuring disparities in vaccination coverage.

Eliminating health disparities in vaccination coverage among various groups is a cornerstone of public health policy. However, the statistical tests traditionally used cannot prove that a state of no difference between groups exists. Instead of asking, "Has a disparity--or difference--in immunization coverage among population groups been eliminated ?," one can ask, "Has practical equivalence been achieved?" A method called equivalence testing can show that the difference between groups is smaller than a tolerably small amount. This paper demonstrates the method and introduces public health considerations that have an impact on defining tolerable levels of difference. Using data from the 2000 National Immunization Survey, the authors tested for statistically significant differences in rates of vaccination coverage between Whites and members of other racial/ethnic groups and for equivalencies among Whites and these same groups. For some minority groups and some vaccines, coverage was statistically significantly lower than was seen among Whites; however, for some of these groups and vaccines, equivalence testing revealed practical equivalence. To use equivalence testing to assess whether a disparity remains a threat to public health, researchers must understand when to use the method, how to establish assumptions about tolerably small differences, and how to interpret the test results.