Diphtheria-tetanus overimmunization in children with no records: can it be prevented?

A pilot study was undertaken to assess the validity of two new tests for predicting the immune response of Toronto schoolchildren with no acceptable evidence of prior administration of diphtheria or tetanus toxoid to a routine booster injection of diphtheria and tetanus (DT) toxoid. The tests, an inexpensive enzyme-linked immunosorbent assay (ELISA) fingerprick test for tetanus antibodies and a modification of the Schick skin test for susceptibility to diphtheria, were administered before the booster injection. One week later the ELISA test was repeated and the result of the modified Schick test read. On both occasions a diphtheria microneutralization assay was done for "gold standard" evidence of prior exposure to diphtheria toxoid or toxin. The results were used to determine the sensitivity and specificity of a single prebooster tetanus ELISA test or a modified Schick test for predicting which children with no records could be safely protected with only one DT booster dose instead of the primary series of three or four doses usually given to such children. Only 6 of the 34 subjects (18%) were totally without prior exposure to tetanus toxoid. Two of the six (6% of 33 subjects) appeared to mount a primary immune response to diphtheria toxoid as well. An initial ELISA titre of 0.01 IU/ml or lower correctly identified all six children needing a full series of tetanus toxoid (sensitivity for a primary immune response 100%) and falsely identified only 3 of 28 immune children as needing the series (specificity for immunity 89.3%). The modified Schick test appeared to have even greater accuracy for identifying children needing a full series of diphtheria toxoid. However, its use, entailing the costs of an extra nurse visit, would have prevented only seven more children from receiving an unnecessary full series of diphtheria toxoid than use of the baseline tetanus ELISA test alone.     

The immunization of children with combined diphtheria and tetanus vaccine in Sweden

Two groups derived from 97 children three-four months of age were vaccinated with diphtheria and tetanus vaccines containing either a routinely prepared diphtheria toxoid or a more purified preparation. Two injections were given with an interval of one month and a third injection was given one year after the first. Prior to the third injection no child was without protection against diphtheria, i.e. had an antitoxin titre less than 0.01 IU ml-1. After the third injection 95 and 94% of the children vaccinated with the routinely and more purified diphtheria toxoids, respectively, had diphtheria antitoxin titres greater than 1 IU ml-1 (estimated to provide protection for at least ten years). Systemic reactions such as fever and malaise occurred in five children. Local reactions greater than 10 cm were observed in three children and reactions greater than 5 but less than or equal to 10 cm were seen in 14% of the children. The routinely prepared combined diphtheria and tetanus vaccine, DT, produced very good immunity against diphtheria with moderate side effects. The use of a more purified diphtheria toxoid in the combined vaccine produced the same immunity and side effects.     

Simultaneous Immunization with B.C.G., Diphtheria-tetanus,and Oral Poliomyelitis Vaccines in Children Aged 13-14

The simultaneous administration of B.C.G. vaccine, diphtheria-tetanus toxoid aluminium hydroxide adsorbed vaccine, and oral poliovaccine was studied in 628 children aged 13-14 years between 1966 and 1969 in Newham, London. The efficacy of these vaccines was unaffected by administering them at the same time; routine simultaneous administration is considered justified when organizational difficulties prevent the attainment of high immunization rates with the vaccines given separately. No adverse reactions to B.C.G. or oral poliomyelitis vaccines took place, but 8% of children had moderately severe local reactions after diphtheria-tetanus aluminium hydroxide adsorbed vaccine, which were attributed to diphtheria toxoid.Serological studies showed the need for immunization against diphtheria, tetanus, and poliomyelitis at 13-14 years of age. Because of the adverse reactions to diphtheria toxoid, however, simultaneous administration of tetanus toxoid aluminium hydroxide adsorbed, oral poliomyelitis, and B.C.G. vaccines only is recommended at present.An “adult type” diphtheria-tetanus toxoid might overcome the problem of reactions, though in two to three years'' time most children aged 13-14 years will have received diphtheria-tetanus-pertussis vaccine in infancy and reinforcement might then be accomplished by a small intradermal dose of the currently available fluid diphtheria-tetanus vaccine.Continued serological studies of diphtheria and tetanus antitoxins and polio antibody are necessary to determine the future need for reinforcement of immunity; such studies should become an essential part of the surveillance of the community immunization programme.     

The immunization of adults against diphtheria in Sweden

Two hundred and three women who disclaimed vaccination against diphtheria were divided into four groups and injected with either 2.0 or 6.25 Lf of a routine diphtheria toxoid or of a more purified preparation. One hundred and twenty-six of these women who did not show a secondary antibody response were given a second and a third injection one month and one year, respectively, after the first injection. Prebooster (third injection) antitoxin titres of greater than or equal to 0.01 IU ml-1 (the minimum level for protection) were found in 22 and 37% of those who received 2.0 and 6.25 Lf, respectively. Postbooster titres of greater than or equal to 1.0 IU ml-1 (calculated to give a protection of at least ten years of duration) were found in 23 and 58% of those who received 2.0 and 6.25 Lf, respectively. The rate of untoward reactions was low. Fever of short duration occurred in five women. Four out of the five women received 6.25 Lf of the more purified diphtheria toxoid and one 2 Lf of the routine toxoid. Local reactions greater than 10 cm were observed in three women. All received the higher dose, 6.25 Lf of diphtheria toxoid. Local reactions greater than 5 but less than or equal to 10 cm occurred in up to 13% (6.25 Lf of diphtheria toxoid). No significant difference between the groups of women vaccinated with routine or more purified toxoid was found. It was concluded that the diphtheria toxoids in the two doses of 2 Lf and 6.25 Lf did not induce a satisfactory immune response. To induce adequate protection the dose of diphtheria vaccine needs to be the same for adults and children, i.e. 12.5 Lf.     

Comparative quantitation for the protein content of diphtheria and tetanus toxoids by DC protein assay and Kjeldahl method.

DPT, a combination vaccine against diphtheria, tetanus and pertussis is available since many years and still continued in the national immunisation schedule of many countries. Although highly potent, reactions to DPT vaccine are well known, mainly attributed to the factors like Pertussis component, aluminum adjuvant and lower purity of tetanus and diphtheria toxoids. The latter most important aspect has become a matter of concern, specially for the preparation of next generation combination vaccines with more number of antigens in combination with DPT.Purity of toxoid is expressed as Lf (Limes flocculation) per mg of protein nitrogen. The Kjeldahl method (KM) of protein nitrogen estimation suggested by WHO and British Pharmacopoeia is time consuming and less specific. Need has been felt to explore an alternative method which is quick and more specific for toxoid protein determination. DC (detergent compatible) protein assay, an improved Lowry's method, has been found to be much more advantageous than Kjeldahl method.     

Use of adsorbed diphtheria-tetanus (DT) toxoid containing different doses of antigens in booster immunizations of children

To decrease the antigenic load in booster immunizations of children against diphtheria and tetanus, the immunological effectiveness and reactogenicity of different doses of both antigens (i. e 1 Lf and 1 BU; 2.5 Lf and 2.5 BU; 5 Lf and 5 BU) were studied. The study revealed that all these doses of the preparation were practically nonreactogenic: the total of systemic reactions was 0.9%. The study of the immunological effectiveness of adsorbed DT toxoid with reduced antigen content revealed the advantage of the commercial dose of the preparation (5 Lf of diphtheria antigen and 5 BU of tetanus antigen) over such doses of diphtheria and tetanus antigens as, respectively, 1 Lf and 1 BU; 2.5 Lf and 2.5 BU. Still, this advantage disappeared as early as 6 months after booster immunization. The results of these investigations indicate that booster immunization of children aged 6 years and over may be made with lower doses of adsorbed DT toxoid with reduced antigen content.     

Persistence of antibody after accelerated immunisation with diphtheria/tetanus/pertussis vaccine.

OBJECTIVE--To determine the persistence of antibody to diphtheria, tetanus, and pertussis in children receiving an accelerated schedule of primary immunisation. DESIGN--Controlled study of antibody testing of blood samples from children immunised according to various schedules: three doses of triple vaccine completed at 8-13 calendar months, 6-7 calendar months, before 6 calendar months, or three doses followed by diphtheria/tetanus before age 2. SETTING--Plymouth Health Authority. SUBJECTS--129 children aged 4 years who had received three doses of diphtheria/tetanus/pertussis vaccine with or without a diphtheria/tetanus booster. MAIN OUTCOME MEASURES--Diphtheria and tetanus antitoxin concentrations and antibody titres to pertussis toxin, filamentous haemagglutinin, and agglutinogens 2 and 3. RESULTS--All children had protective concentrations of antitoxin to diphtheria and tetanus (greater than or equal to 0.01 IU/ml). There was no evidence of a significant difference in diphtheria or tetanus antitoxin concentrations and pertussis antibody titres in children immunised with an accelerated course (third dose of triple vaccine before 6 months) compared with those who received a longer course (third dose at 8-13 months) with no booster (geometric mean antitoxin concentration 0.411 (95% confidence interval 0.273 to 0.618) v 0.426 (0.294 to 0.616) for diphtheria and 0.358 (0.231 to 0.556) v 0.299 (0.197 to 0.453) for tetanus; geometric mean antibody titres 903 (500 to 1631) v 1386 (848 to 2266) for pertussis filamentous haemagglutinin, 179 (130 to 248) v 232 (167 to 322) for pertussis toxin, and 2002 (1276 to 3142) v 3591 (2220 to 5809) for agglutinogens 2 and 3). CONCLUSION--Immunisation with three doses of triple vaccine at monthly intervals completed before 6 months of age probably provides adequate protection against diphtheria, tetanus, and whooping cough which will persist until the age of the preschool booster.     

Immunity to diphtheria and tetanus in some of the administrative territories of the RSFSR

The article deals with the state of immunity to diphtheria and tetanus among the adult population in some administrative regions of the RSFSR. Of the children and adults covered by the survey, 91.3-96.7% were found to have protective antibody titers against diphtheria and 98.7-100%, against tetanus. An essential drop in the level of immunity to diphtheria in persons over 18 years of age was revealed: 71.7% of them were nonimmune, which correlated with the high morbidity rate among these persons. At the same time the percentage of adults nonimmune to tetanus was considerably lower than that of adults nonimmune to diphtheria, reaching only 27.1%. The state of immunity to tetanus in adults was found to depend on the seasons.     

Immune response in adult immunized with adsorbed DT-M anatoxin with reduced antigen content and Imovax-DT-adulte vaccine

The comparative study of immune response after immunization of adults with adsorbed DT toxoid with reduced antigen content and Imovax-DT-adulte vaccine, as well as the safety of these preparations, was made. The study revealed that immunization of adults with adsorbed DT toxoid having reduced antigen content, made in two injections, and the injection of Imovax-DT-dulte vaccine, as well as the successive injection of these preparations, produced the same the levels of antitetanus immunity. Antidiphtheria immunity, evaluated by the number of seroconverted to diphtheria persons following two injections immunization was similar for the two preparations, while the level of antidiphtheria antibodies was higher in persons immunized with adsorbed DT toxoid. The immune stratum index was rather high among persons aged 16-29 years. This age group exhibited the highest number of persons, seropositive to both diphtheria and tetanus. Both vaccine preparations, adsorbed DT toxoid with reduced antigen content and Imovax-DT-adulte vaccine, were found to be equally capable of inducing autoimmune reactions in the vaccinees, detected by laboratory methods.     

Change in immunisation schedule and sudden infant death syndrome in Hungary

Infant mortality in Hungary was higher than in other European countries; however, the reported incidence of sudden infant death syndrome (SIDS) has been lower than those for Western Europe and the United States. Childhood immunisation has been reported to be a protective factor for SIDS. In Britain, the change to an earlier immunisation schedule for diphtheria, pertussis, and tetanus appeared to be associated with a shift in the age distribution of SIDS. In 1999, immunisation for Haemophilus influenzae type b (Hib) was introduced for Hungarian infants at the age of 2 months. Data for total infant mortality and SIDS in Hungary were analysed between 1990 and 2002. Infection was the major cause of death among Hungarian infants followed by SIDS. Following introduction of Hib immunisation, there was a decrease in deaths due to meningitis from an average of 3.5% of all infant deaths between 1990 and 1998 to an average of 1% of all infant deaths between 1999 and 2002 (p=0.00). There was also a significant decrease in the proportion of SIDS in the age range > or =2 months from 48% in the earlier period to 39% after introduction of the vaccine (p=0.03). The decrease in SIDS might be due in part to decrease in unrecognised Hib infections or to induction of antibodies by the tetanus toxoid to which the Hib polysaccharide is conjugated that are cross reactive with bacterial toxins implicated in SIDS.     

Immunity of children to diphtheria,tetanus, and poliomyelitis.

A survey of titres of diphtheria and tetanus antitoxins and of antibodies to polioviruses in the sera of 291 schoolchildren aged 15, 11, and 7 years showed that high immunisation rates can evoke protective concentrations of tetanus antitoxin in 98% of children and protective levels of the antibodies to diphtheria and all three types of poliomyelitis in 85% of children. Reinforcing immunisation at school entry appeared to be necessary to maintain adequate titres of diphtheria antitoxin in children up to 15 years of age, not essential to maintain adequate titres of tetanus antitoxin, and to have little effect on the titres of antibodies to poliomyelitis.     

The immunological effectiveness of small doses of diphtheria and tetanus anatoxins in the revaccination of children with allergy-altered reactivity and adults

The possibility of decreasing the content of antigens in adsorbed diphtheria-tetanus toxoid, used for the booster immunization of children with allergically altered responsiveness and adults, is shown. Diphtheria toxoid in doses of 1-2.5 Lf and tetanus toxoid in doses of 1-2.5 binding units possessed sufficiently high immunological effectiveness in combination with low reactogenicity and good tolerance. In 6-12 months after booster immunization with decreased doses of toxoids 100% of children with allergy of different character and, respectively, 86-94% and 95% of adults have developed protective levels of antibodies to diphtheria and tetanus.     

Role of whole-cell pertussis vaccine in severe local reactions to the preschool (fifth) dose of diphtheria-pertussis-tetanus vaccine.

OBJECTIVE: To estimate the contribution of whole-cell pertussis vaccine to severe local reactions after the preschool (fifth) dose of adsorbed diphtheria toxoid-pertussis vaccine-tetanus toxoid (DPT) vaccine. DESIGN: Double-blind randomized controlled trial. SETTING: Urban community. PARTICIPANTS: Volunteer sample of 200 healthy children 4 to 6 years old who were eligible for the fifth dose of DPT vaccine. INTERVENTIONS: Children received, in both arms, either diphtheria toxoid-tetanus toxoid (DT) and monovalent pertussis vaccines (group A, 99 children) or DPT and meningococcal vaccines (group B, 101 children). All were licensed products from single lots. The children were assessed 24 hours later by a trained observer. Serum samples obtained before vaccination were tested for antibodies to tetanus and diphtheria toxins and five pertussis antigens by means of enzyme-linked immunosorbent assay. MAIN OUTCOME MEASURES: Rates of severe local reactions (an area of redness or swelling or both of 50 mm or greater) 24 hours after vaccination. Relation between serum antibody levels before vaccination and rates of severe local reactions to corresponding vaccines. RESULTS: All of the subjects were followed up 24 hours after vaccination. Severe redness was present in 38% given DPT vaccine, 29% given intramuscular pertussis vaccine and 9% given DT vaccine (p < or = 0.002, three-way comparison). Severe swelling was common after vaccination with all three products. After intramuscular pertussis vaccination a relation was evident between the prevaccination levels of antibody to whole-cell pertussis bacteria and the rates of redness (p < 0.02) but not between the prevaccination subcellular antibody levels and the rates of redness. CONCLUSION: That pertussis vaccine resembled the DPT vaccine in causing severe redness suggests that it is the principal cause of such reactions after DPT vaccination. The DT vaccine was also reactogenic; thus, cumulative sensitization to one or more of its constituents may be a factor.     

Preparative Procedure for the Purification of Toxoids by Gel Filtration

Sephadex gel filtration can be employed as a preparative procedure for the purification of both tetanus and diphtheria toxoids. A toxoid purification sequence is described in the text. By utilizing the described methods and columns, up to 100,000 human doses of diphtheria toxoid could be processed in a single operation. The method has given an 80% yield of diphtheria toxoid with a purity of 1,900 Lf per mg of N. The analysis of the material by immunodiffusion tests showed that a marked increase in purity was achieved. Antigenicity tests demonstrated that there was no significant difference in antigenic potency between the parent toxoid and its purified fraction. Factors limiting the effective separation of tetanus toxoid by gel filtration are discussed. The construction of the columns used is described in detail, as well as packing procedures and column characteristics such as bed volume, void volume, sample size, and flow rate.     

Humoral immunity to diphtheria and tetanus in pregnant women and newborn infants

Pregnant and parturient women have been examined in different regions of the USSR: Moscow, the Turkmen SSR, the Azerbaijan SSR and the Uzbek SSR. Altogether 720 placental sera and 522 funic sera have been checked for the presence of antibodies to diphtheria and tetanus toxoids in the passive hemagglutination test. Considerable groups of women with the insufficient level of immunity to diphtheria (40-66%) and tetanus (42.1-58.8%) have been revealed in different republics. Among women over 70 years the percentage of persons with the absence of antibodies or having low antibody titers has proved to be even higher. The comparative analysis of antibody titers has shown a correlation between antibody titers in mothers and newborn infants in 83.6% of cases for diphtheria toxoid and in 72.9% of cases for tetanus toxoid. These data show that among parturient women and newborn infants large groups remain unprotected against diphtheria and tetanus, which indicates the necessity of correcting the immune status of women of the productive age.     

Booster vaccination against tetanus and diphtheria: insufficient protection against diphtheria in young and elderly adults

We have recently demonstrated that single shot vaccinations against tetanus and diphtheria do not lead to long-lasting immunity against diphtheria in elderly persons despite administration at 5 year intervals. In the present study we have immunized a group of young adults against tetanus and diphtheria to compare the pre- and 28 days post-vaccination immune responses in the young group with results of the same vaccination performed in an elderly group of a previous study. We also studied protection in both groups 5 years after vaccination. We compared antibody titers at all three time points and also analyzed the T cell responses in both age groups 5 years after vaccination.Before vaccination 9 % of the elderly persons were not protected against tetanus, and 48 % did not have protection against diphtheria. In the young group all participants were protected against tetanus, but 52 % were also unprotected against diphtheria before vaccination. 28 days after vaccination 100 % of all participants had protective antibody concentrations against tetanus and only a small percentage in each age group (<10 %) was unprotected against diphtheria. 5 years later, 100 % of both cohorts were still protected against tetanus, but 24 % of the young and 54 % of the elderly group were unprotected against diphtheria. Antibody concentrations against diphtheria measured by ELISA correlated well with their neutralizing capacity. T cell responses to tetanus and diphtheria did not differ between young and old persons. We conclude that booster vaccinations against tetanus and diphtheria according to present recommendations provide long-lasting protection only against tetanus, but not against diphtheria, independently of age. In elderly persons, the level of protection is even lower, probably due to intrinsic age-related changes within the immune system and/or insufficient vaccination earlier in life.     

Subacute toxicity of adsorbed 250 Lf tetanus toxoid in rats

Since the naturally acquired tetanus antitoxin titre in Indian population is mostly less than protective levels, to minimise the incidence of morbidity, Glaxo Laboratories (India) Ltd., Bombay have prepared a single dose potent tetanus vaccine of 250 Lf as compared to 5 Lf previous tetanus toxoid. Subacute toxicity study revealed that this toxoid (250 Lf) injected at different dose levels (1-2 ml/rat/injection x 4) is non-toxic to rats.     

双佐剂包被的破伤风类毒素马匹免疫试验

为提高破伤风免疫马匹的血浆抗体效价,应用不同佐剂配制TT抗原,进行马匹超免疫比较研究;采用FIA和植物油双佐剂包被与单佐剂包被的TT抗原,注射马匹进行超免疫,比较三组血浆的效价;结果显示,双佐剂抗原较单佐剂的免疫效果好,但可能对马匹刺激较强,有待调整注射剂量和免疫程序。     

Quantitative estimation of diphtheria and tetanus toxoids. 4. Toxoids as international reference materials defining Lf-units for diphtheria and tetanus toxoids

The Lf-unit, which is used in the control of diphtheria and tetanus toxoid production and in some countries also to follow immunization of horses for production of antitoxins, has hitherto been defined by means of antitoxin preparations. A diphtheria toxoid and a tetanus toxoid preparation, both freeze-dried, were examined in an international collaborative study for their suitability to serve as reference reagents in the flocculation tests and for defining the Lf-units. It was shown that flocculation tests using the reference toxoids are very reproducible and reliable and the WHO Expert Committee on Biological Standardization established: the toxoid called DIFT as the International Reference Reagent of Diphtheria Toxoid for Flocculation Test with a defined content of 900 Lf-units of diphtheria toxoid per ampoule; and the toxoid called TEFT as the International Reference Reagent of Tetanus Toxoid for Flocculation Test with a defined content of 1000 Lf-units of diphtheria toxoid per ampoule.     

The identification of diphtheria, tetanus and pertussis vaccines by single radial and double immunodiffusion techniques

The identification tests for adsorbed diphtheria, tetanus and pertussis vaccines, which are required by the European Pharmacopoeia to be undertaken in animals, may be replaced by precipitation tests, for instance in agaros gels. Such in vitro tests eliminate the use of animals and are less expensive and time-consuming. The single radial immunodiffusion technique is a suitable semiquantitative test, while the double diffusion test is necessary for the investigation of complete or partial identity. The precipitates obtained in the single radial diffusion tests and in double diffusion tests with diphtheria toxoid were visible without staining; those obtained in the double diffusion tests with tetanus toxoid were weaker and staining was sometimes needed.