สารบัญ

Category Active immunizing agent.

      Cholera Vaccine is a sterile suspension, in isotonic sodium chloride solution or other suitable diluent, of the smooth strains of the two main serological types, Inaba and Ogawa of killed Vibrio cholerae classical biotype. Each 1.0 ml contains not less than 4000 million organisms of each serotype. Either a single strain or several strains of each type may be included. All strains must contain, in addition to their type O antigens, the heat-stable O antigen common to Inaba and Ogawa.

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

Description Slightly turbid to milky suspension; odour, nearly odourless or of the antimicrobial agent.

Strength available 8000 million killed V. cholerae per ml.

Dose Adults and children 10 years of age and over: Subcutaneous or intramuscular, 0.5 ml, repeat at 1- to 4-week intervals, 0.5 ml.

Intradermal, 0.2 ml, repeat at 1- to 4-week intervals, 0.2 ml.

Children 5 to 10 years of age: Subcutaneous or intramuscular, 0.3 ml, repeat at 1- to 4-week intervals, 0.3 ml.

Children under 5 years of age: Subcutaneous or intramuscular, 0.2 ml, repeat at 1- to 4-week intervals, 0.2 ml.

Infant 6 months to 1 year of age: Subcutaneous or intramuscular, 0.2 ml, repeat at 1- to 4-week intervals, 0.2 ml.

Booster doses are required every 6 months while an individual is at continual risk.

Contra-indication

1. It is contra-indicated in individuals with acute infections.

2. It is contra-indicated in individuals with immune deficiency conditions who are taking corticosteroids or other immunosuppressive agents.

3. It is contra-indicated in individuals with a history of severe systemic or allergic reactions to cholera vaccine.

Warning

1. It is not for intravenous administration.

2. Do not administer intramuscularly to persons with thrombocytopenia or any coagulation disorders.

3. Fever; headache; malaise; pain, redness or swelling at the injection site may occur.

Additional information

          1. Immunization against cholera is not recommended in infants under 6 months of age.

          2. Appropriate precautions should be taken prior to vaccine injection to prevent allergic or any other unwanted reactions. This should include review of the patient’s history regarding possible sensitivity and the ready availability of epinephrine 1:1000 and other appropriate agents used for control of immediate allergic reactions.

          3. Even after immunization with cholera vaccine, not all recipients of the vaccine will be fully protected against cholera. Travellers should take all necessary precautions to avoid contact with, or ingestion of, potentially contaminated food or water.

          4. Cholera vaccine does not prevent V. cholerae excretion. Therefore, it should not be used to manage contacts of imported cholera cases or to control the spread of infection, even during epidemics.

Expiration date When stored under the prescribed conditions, the expiration date is not later than 18 months from the date of the last satisfactory potency test.

Labelling Complies with the “General Information for Biological Products”, p. 177. In addition the label on the container states (1) the method used to inactivate the bacteria; (2) the number of bacteria in each human dose; (3) that it is to be well shaken before use.

Identification Identify the organisms by specific agglutination.

pH 6.8 to 7.4 (Appendix 4.11).

Phenol If phenol has been used in the preparation, the concentration is not more than 0.50 per cent w/v. Carry out the test as described under the “Determination of Phenol”, p. 179.

Assay The potency of a Cholera Vaccine is determined by comparing the dose necessary to protect mice against a lethal intraperitoneal dose of Vibrio cholerae with the dose of the National of International Reference Preparation of Cholera Vaccine necessary to give the same protection.

SUGGESTED METHOD

      Selection of challenge strain Select a suitable strain of each serotype, Inaba and Ogawa of V. cholerae classical biotype. The strains, suspended in gastric mucin or other resistance-lowering substance, should have adequate virulence which is evaluated by determining the LD₅₀ in mice, after 72-hour intraperitoneal injection. The LD₅₀ should be 10,000 or fewer colony-forming units.

      LD₅₀ The number of V. cholerae organisms that kills 50 per cent of a group of mice within 72 hours when injected by the intraperitoneal route.

      Preparation of challenge suspension Make one subculture from the strain and suspend the harvested V. cholerae in saline TS. Determine the opacity of the suspension. Prepare in gastric mucin or other resistance-lowering substance a series of dilutions of the suspension, and allocate each dilution to a group of 10 mice. Inject intraperitoneally into each mouse a dose (0.5 ml) of the dilution allocated to its group and count the number of mice surviving in each group after 72 hours. Calculate the titre of the challenge suspension in LD₅₀ per challenge dose by the standard statistical methods. From the result calculate the opacity of a suspension containing not less than 100 and not more than 10,000 LD₅₀ per challenge dose.

      For the determination of the potency of the vaccine being examined make a fresh subculture from the same strain of V. cholerae and from the harvested organisms prepare a suspension of an opacity corresponding to about 1000 LD₅₀ in each challenge dose. Prepare three dilutions of the challenge suspension.

      Selection and distribution of test animals Use 3 to 4 weeks old mice of a suitable strain, drawn from a uniform stock, keeping the range of weight not more than 5 g. For the test of each serotype, distribute the mice into six groups of not less than 15 and four groups of 10; the mice should be of the same sex or the sexes should be equally distributed among the groups. Three of the groups of 15 receive the Reference Preparation and the other three the vaccine being tested; the four groups of 10 are used for the titration of the LD₅₀ of the challenge suspension.

      Determination of the potency of the vaccine For the test of each serotype, use three doses of the Reference Preparation and three of the vaccine being tested, diluted with saline TS. In each case, the three doses should be so arranged that the dose protecting 50 per cent of the mice is as near as possible to the middle of the dose range. Give each mouse one dose (0.5 ml) by intraperitoneal injection.

      Twelve to fourteen days later, challenge the mice reserved for Inaba serotype test intraperitoneally with V. cholerae Inaba, and the mice reserved for Ogawa serotype test with V. cholerae Ogawa. The challenge dose should be chosen to contain approximately 1000 LD₅₀. This is confirmed by titrating at the same time the challenge suspension in the four groups of 10 nonimmunized control mice. Inject one group of control mice with the challenge dose and the other three, with graded tenfold dilutions of the challenge dose. Simultaneously, inoculate a suitable solid medium with measured amounts of appropriate dilutions of the challenge culture to determine the number of colony-forming units in 1 ml. Observe the mice for 72 hours and record the number of deaths and survivals. Calculate the results of the assay by standard statistical methods from the number of mice surviving. The vaccine passes the test if the potency of the vaccine under test is not less than that of the Reference Preparation of both serotypes.

      The test is not valid unless, for both the test vaccine being examined and the Reference Preparation, the 50 per cent protective dose lies between the largest and smallest doses given to the mice, the slopes of the dose response curves are significant with no significant deviation from linearity or parallelism and the challenge dose is approximately 1000 LD₅₀.

      The estimated potency of the test vaccine shall be not less than that of the National or International Reference Preparation of Cholera Vaccine upon statistical comparison of the results.