Doses Of DTP Research Articles

Safety and immunogenicity of hydrogen peroxide-inactivated pertussis toxoid in 18-month-old children

The immunogenicity and adverse effects of an acellular pertussis vaccine consisting of a purified pertussis toxin inactivated with hydrogen peroxide (PTxd) was evaluated. Children aged 15 to 30 months were injected with 10 (n = 33) or 50 μg (n = 34) of PTxd or with diphtheria and tetanus toxoids and whole cell pertussis vaccine (DTP) (n = 34). All children had previously received three doses of DTP during infancy. Both dosages of PTxd induced higher IgG antibody (p < 0.05 for 10 μg dose and p < 0.01 for 50 μg dose) and pertussis antitoxin responses (p < 0.01 for 50 μg dose) than DTP. The 50 μg dose gave slightly higher (though not significantly) antibody responses than the 10 μg dose of PTxd. None of the vaccines induced detectable IgM or IgA antibody responses to pertussis toxin. At 24 h, local reactions occurred in none of the children injected with 10 μg PTxd, 12% with 50 μg PTxd and 78% with DTP. Fever at 24 h occurred in 13% after 10 μg PTxd, in none after 50 μg PTxd and in 53% after DTP. Recipients of DTP, but not of PTxd, had significant increases in neutrophils and decreases in lymphocytes and haematocrit at 24 h (all p < 0.05). None of the groups showed changes in blood glucose at 24 h. PTxd induced pertussis toxin antibody levels similar to those observed in patients convalescing from natural pertussis. This acellular pertussis vaccine deserves further evaluation for safety and immunogenicity in infants and for efficacy in preventing pertussis.

Revised DTP Immunization Advisory in 1991

PHYSICIANS may have more latitude in deciding whether to continue immunizing infants with the diphtheria and tetanus toxoids and pertussis (DTP) vaccine in the face of adverse effects. The Immunization Practices Advisory Committee of the Centers for Disease Control (CDC), Atlanta, Ga, is expected to eliminate three heretofore absolute contraindications to additional doses of DTP: convulsions with or without fever occurring within 3 days of immunization, a persistent, high-pitched cry within 48 hours of vaccination, and inconsolable crying that lasts for 3 hours or more. All would be placed in a new category called precautions. Four reactions would continue to be listed as absolute contraindications: immediate anaphylactic reaction, a temperature of 40.5°C or higher within 48 hours of vaccination, a hypotonic-hyporesponsive episode within 48 hours of vaccination, and encephalopathy within 7 days of vaccination. The revised recommendations are in the final draft and are expected to be issued next year,

Longitudinal Study of Adverse Reactions Following Diphtheria-Tetanus-Pertussis Vaccine in Infancy

A prospective study of immunogenicity and adverse effects of 1553 doses of diphtheria and tetanus toxoids and whole cell pertussis vaccine (DTP) was performed in 538 children observed longitudinally from 2 months to 20 months of age. Subjects were randomized to the standard four-dose immunization schedule or to a three-dose schedule (with a saline injection substituted for DTP at 6 months of age). The three-dose schedule could not be recommended on the basis of serologic data. Compliance for completing a clinical observation form in the 48 hours following injections was greater than 99%. Fever, local reactions, or adverse behavioral effects were described in association with 96% of DTP doses and 36% of placebo injections. Contraindications to DTP immunization developed in 3% of study children. No convulsion, hypotonic hyporesponsive episode, encephalopathy, or temperature greater than 40.5 degrees C occurred. Behavioral and local inflammatory effects occurred maximally in the first 6 hours following vaccine but fever peaked later. There was no interrelationship between occurrence of local reaction and fever. Data suggest that age has more effect on the type and rate of adverse clinical events than does vaccine dose number. Existing antibody levels to vaccine components, lot of vaccine, breast-feeding, or gestational age did not affect rate or type of clinical reactions. Neither occurrence of reactions nor the use of acetaminophen affected antibody response to vaccine.

Half-Dose Immunization for Diphtheria, Tetanus, Pertussis: Response of Preterm Infants

The American Academy of Pediatrics currently recommends administering full-dose diphtheria, tetanus, pertussis, (DTP) vaccine to preterm infants, beginning at 2 months' chronologic age. Many physicians, however, continue to administer DTP vaccine at a reduced dosage in an attempt to lessen side effects. This study was designed to quantitate the immune response of 20 preterm infants immunized with half-dose DTP vaccine and to determine the nature and extent of side effects. Control subjects were 25 preterm infants immunized with full-dose vaccine. Although 96% of infants who received a full dose were able to mount a serologic response to pertussis after a second dose of DTP, 45% of infants who received a half dose were unable to mount a similar immune response to pertussis even after a third dose of DTP and required a full-dose (fourth dose of DTP) vaccine to better ensure protection. Serologic responses to diphtheria and tetanus were similar in the two groups. The incidence of side effects in preterm infants receiving both full-dose and half-dose DTP was less than that seen in a full-term population. Thus, the physician caring for the preterm infant should adhere to the American Academy of Pediatrics' recommendation for the immunization of preterm infants and offer full-dose DTP vaccine at the routine time intervals of 2, 4, 6, and 15 or 18 months' chronologic age to ensure adequate protection.

IgG and IgG subclass specific antibody responses to diphtheria and tetanus toxoids in newborns and infants given DTP immunization.

To evaluate immune responses to diphtheria and tetanus toxoids in infants we used enzyme-linked immunosorbent assays to detect total IgG and specific IgG-1, IgG-2, IgG-3, and IgG-4 antibody. One group of infants received a newborn dose and subsequently received the usual three doses of DTP. A second group of infants received only the routine dosage at 2, 4, and 6 months of age. In sera acquired at birth, 6, and 9 months of age, there were no statistically significant differences between the two vaccine groups in IgG antibody responses to diphtheria or tetanus, or in IgG subclass tetanus-specific antibody responses. In individual children, tetanus-specific subclass responses were similar in pattern to that for total IgG tetanus antibody, i.e. each IgG subclass response appeared to be regulated by similar mechanisms in that child, but the regulation differed between children. In contrast to a prior study of pertussis immunity, maternally acquired antibody did not significantly affect immune responses to diphtheria or tetanus toxoid by 9 months of age. There was no discernible tolerance due to early tetanus or diphtheria immunization or to high levels of maternally acquired antibody.

Pertussis epidemic in Oklahoma. Difficulties in preventing transmission.

From Jan 1 to Dec 31, 1983, 351 cases of pertussis were reported in Oklahoma. Overall, 59% of the cases were among children 3 months to 6 years of age, the target age group for pertussis vaccination; only 42% of the patients in this age group were appropriately immunized for age with diphtheria and tetanus toxoids and pertussis vaccine (DTP). A survey of 185 households in the neighborhoods of three cases found that only 65% of 57 children 3 months to 6 years of age were appropriately immunized for their age. Aggressive control of the outbreak was attempted in Oklahoma County with recommendations for widespread vaccination against pertussis. However, the effort failed to immunize 82% of the 931 children in the initial target group. Nonetheless, analysis of the reported cases suggested that less than one fourth of the cases were potentially preventable by a single additional dose of DTP, ie, in individuals 3 months to 6 years of age with a history of at least one prior dose of DTP who were not appropriately immunized for age. The optimal solution to outbreak control is outbreak prevention by ensuring that the maximal number of children younger than 7 years of age receive routine age-appropriate DTP vaccination.

On fractional DTP doses

I agree with Dr. Brunell that fractional doses of DTP are not recommended as a means of conserving supply (News and Comment, p. 12). In a recent study, Barkin et al was able to show that the severity and incidence of adverse reactions could be reduced by giving half (0.25 ml) of the standard dose of DTP vaccine.1 After the primary immunization series, 97.6 and 97.3 percent of the infants given the reduced and standard doses, respectively, had pertussis agglutinin titers of more than or equal to 1:16.

Immunization of Indochinese Refugees

To the Editor.— In follow-up of the description of Deinard et al (243:2156, 1980) of a patient with otogenous tetanus, we would like to comment on one of their conclusions and to inform readers about an immunization program for Indochinese refugees who are coming to the United States. The recommended schedule for unimmunized children between the ages of 2 months to 7 years consists of three doses of diphtheria and tetanus toxoids and pertussis vaccine (DTP) given at four- to eight-week intervals followed by a fourth dose 12 months later and a booster dose at the time of school entry. 1 These recommendations provide for optimal protective antibody titer responses. In the patient described by Deinard et al, the clinical onset of tetanus occurred within five days of immunization, and only one dose of DTP had been documented with certainty. Consequently, it is not surprising that the child had not