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Pertussis Vaccine (Acellular, Component, Adsorbed); Whooping-cough Vaccine (Acellular Component)

Category Active immunizing agent.

      Adsorbed Pertussis Vaccine (Acellular Component) is a sterile suspension, in saline solution or other appropriate solution isotonic with the blood, of the individually prepared and purified antigenic components of Bordetella pertussis, which are adsorbed onto suitable adjuvant(s), such as aluminium hydroxide or aluminium phosphate.

      The vaccine contains either pertussis toxoid or a pertussis-toxin-like protein free from toxic properties, produced by expression of a genetically modified form of the corresponding gene. Pertussis toxoid is prepared from pertussis toxin by a method that renders the latter harmless while maintaining adequate immunogenic properties and avoiding reversion to toxin. The vaccine may also contain filamentous haemagglutinin, pertactin (a 69 kDa outer-membrane protein) and other defined components of B. pertussis,​ such as fimbrial-2 and fimbrial-3 antigens. The latter 2 antigens may be copurified. The antigenic composition and characteristics are based on evidence of protection and freedom from unexpected reactions in the target group for which the vaccine is intended.

      The vaccine complies with the requirements stated under Vaccine, with the following modifications.

Dose Intramuscular or deep subcutaneous, 0.5 ml, usually as a component in Adsorbed Diphteria, Tetanus and Pertussis (Acellular Component) Vaccine. Contra-indication; Warning See under Pert

Contra-indication; Warning See under Pertussis Vaccine, Adsorbed, p. 262.

Additional information Adsorbed Pertussis Vaccine (Acellular Component) has been developed to reduce the frequency and severity of both local and systemic adverse reactions associated with Adsorbed Pertussis Vaccine.

      See also under Pertussis Vaccine, Adsorbed, p. 262.

Expiration date When stored under the prescribed conditions, the expiration date is not later than 2 years from the date of the last satisfactory test for potency.

Labelling Complies with the “General Information for Biological Products”, p. 177. In addition the label on the container states (1) the names and amounts of the components present in the vaccine; (2) where applicable, that the vaccine contains a pertussis toxin-like protein produced by genetic modification; (3) the name and the amount of the adjuvant(s); (4) that it is not to be frozen; (5) that it must be well shaken before use.

Identification Subject the vaccine to a suitable desorption procedure such as the following: dissolve in the vaccine being examined sufficient sodium citrate dihydrate to give a 1 per cent w/v solution; maintain at 37º for about 16 hours and centrifuge until a clear supernatant liquid is obtained. Examined by a suitable immunochemical method (Appendix 14.5), the clear supernatant liquid reacts with specific antisera to the components stated on the label.

Absence of residual pertussis toxin and irreversibility of pertussis toxiod.

      (Note This test is not necessary for the product obtained by genetic modification.) Use three groups each of not less than five histamine-sensitive mice. Inject intraperitoneally into the first group twice the single human dose of the vaccine stored at 2º to 8º. Inject intraperitoneally into the second group twice the single human dose of the vaccine incubated at 37º for 4 weeks. Inject diluent into the third group of mice. After 5 days, inject into each mouse 2 mg of histamine base intraperitoneally in a volume not exceeding 0.5 ml and observe for 24 hours. The test is invalid if one or more control mice die following histamine challenge. The vaccine complies with the test if no animal in the first or second group dies following histamine challenge. If one mouse dies in either or both of the first and second groups, the test may be repeated with the same number of mice or with a greater number and the results of valid tests combined; the vaccine complies with the test if, in both of the groups given the vaccine, not more than 5 per cent of the total number of mice die following histamine challenge.

      The histamine sensitivity of the strain of mice used is verified at suitable intervals as follows: inject intravenously threefold dilutions of a reference pertussis toxin preparation in phosphate-buffered saline solution containing 0.2 per cent w/v of gelatin and challenge with histamine as above; the strain is suitable if more than 50 per cent of the animals are sensitized by 50 ng of pertussis toxin and none of the control animals injected with only diluent and challenged similarly with histamine show symptoms of sensitization.  

Antimicrobial preservative Where applicable, determine the amount of antimicrobial preservative by a suitable chemical or physicochemical method. The amount is not less than the minimum amount shown to be effective and is not more than 115 per cent of the quantity stated on the label.

Assay

      The capacity of the vaccine to induce the formation of specific antibodies is compared with the same capacity of a reference preparation examined in parallel; anitbodies are determined using suitable immunochemical methods (Appendix 14.5) such as enzymelinked immunosorbent assay (ELISA). The test in mice shown below uses a three-point model but, after validation, for routine testing a single-dilution method may be used.

      Reference vaccine A batch of vaccine shown to be effective in clinical trials or a batch representative thereof is used as a reference vaccine. For the preparation of a representative batch, strict adherence to the production process used for the batch tested in clinical trials is necessary. The stability of the reference vaccine shall be documented.

      Reference antiserum Bordetella pertussis mouse antiserum of National or International Standard is suitable for use as a reference antiserum.

      Requirement The capacity to induce antibodies is not significantly (P = 0.95) less than that of the reference vaccine.

      (Note The following test model is given as an example of a method that has been found to be satisfactory.)

      Selection and distribution of test animals Use in the test healthy mice of the same stock 4 to 8 weeks old. Distribute the animals in 6 groups of a number appropriate to the requirements of the assay. Use 3 dilutions of the vaccine being examined and 3 dilutions of a reference preparation and attribute each dilution to a group of mice. Inject intraperitoneally or subcutaneously into each mouse 0.5 ml of the dilution attributed to its group.

      Collection of serum samples After 4 to 5 weeks of vaccination, bleed the mice individually under anaesthesia. Store the sera at –20º until tested for antibody content.

      Antibody determination Assay the individual sera for content of specific antibodies to each component using a validated method such as the ELISA test shown below.

      ELISA test Coat microtitre plates (polyvinyl chloride or polystyrene as appropriate for the specific antigen) with the purified antigen at a concentration of 100 ng per well. After washing, block unreacted sites by incubating with a solution of bovine serum albumin and then washing. Make twofold dilutions of sera from mice immunized with test or reference vaccines on the plates. After incubation at 22º to 25º for 1 hour, wash the plates. Add a suitable solution of anti-mouse IgG enzyme conjugate to each well and incubate at 22º to 25º for 1 hour. After washing, add a substrate from which the bound enzyme conjugate liberates a chromophore which can be quantified by measurement of absorbance (Appendix 2.2). Design the test conditions to obtain a linear response for absorbance with respect to antibody content over the range of measurement used and absorbance values within the range 0.1 to 2.0.

      Use a reference antiserum of assigned potency in the test as the basis for calculation of the antibody levels in test sera. Also include a standardized control serum in the test.

      The test is not valid if: (a) the value found for the control serum differs by more than 2 standard deviations from the assigned value; (b) the confidence limits (P = 0.95) are less than 50 per cent or more than 200 per cent of the estimated potency.

      Calculation Calculate the antibody titers in the sera of mice immunized with reference and test vaccines and from the values obtained calculate the potency of the test vaccine in relation to the reference vaccine by the “Statistical Analysis of Results of Biological Assay and Test” (Appendix 9).