Status: marketed worldwide

Organizations involved:

Berna Biotech Ltd. – Manuf.; Tech.

Berna Products, Corp. – USA Mark.

Crucell N.V. – Parent

Novartis Vaccines and Diagnostics Ltd. – Europe mark.

Novartis AG – Parent

Acambis plc – Former

Swiss Serum and Vaccine Institute Berne – R&D; Tech.; Former

Chiron Corp. – Former

Behringwerke AG – Former

Evans Vaccines Ltd. – Former.

PowderJect Pharmaceuticals plc – Former

Institut Zug Eforschung der Infektionkranhelten – Tech.; Former

Cross ref: See Typhoid Vaccine Products (entry #560).

Description: Typhoid Vaccine Live Oral Ty21a or Vivotif Berna is a formulation of live attenuated lyophilized (freeze-dried) Salmonella typhi strain Ty21A for oral ingestion packaged in enteric coated (to resist stomach acid inactivation) gelatin capsules. This was the first oral bacterial vaccine licensed by FDA.

The vaccine contains at least 2 to 6 x 109 (2-6 billion) viable live attenuated S. typhi (strain Ty21a) bacteria, along with 6 to 50 x 109 (6-50 billion) nonviable S. typhi Ty21a. The vaccine is lyophilized (freeze-dried) and prepared in capsule form for oral administration. Each capsule also contains 26-130 mg of lactose (or sucrose), 1.4-1.7 mg of amino acid mixture, 3.6-4.4 mg of magnesium stearate and ascorbic acid (vitamin C). The vaccine is packaged as four single dose capsules in blister packages of four. The vaccine is stored at 2-8˚C (refrigerated) and has a shelf life of 15 months. The vaccine can tolerate 48 hours at 25˚C (77˚F).

Nomenclature: Typhoid Vaccine/Berna [BIO]; Vivotif Berna [TR]; Typhoid Vaccine Live Oral Ty21a [FDA]; Salmonella typhi vaccine [SY]; Ty21a typhoid vaccine [SY]; Typhoral [TR in Germany]; NDC 58337-0003-01 [NDC]

Biological.: This attenuated S. typhi Ty21a strain replicates in the lower intestinal tract; and the whole bacterium, particularly its surface proteins and polysaccharides, induce S. typhi-neutralizing antibodies. The mechanism by which Ty21a vaccine confers protection is unknown. However, it elicits both serum (antibody; IgG) antibodies, intestinal (mucosal; IgA) antibodies, and cell-mediated immune responses.

The S. typhi Ty21a strain has a defect (Ty21a gal E mutation) in the enzyme uridine diphosphate-galactose-4-epimerase. The enzymatic activities of bacterial galactopermease, galacto-kinase, and galactose-1-phosphate uridyl-transferase are reduced by 50-90%. The strain is nonvirulent in mice. The Ty21a strain does not contain Vi antigen.

Companies.: The vaccine was developed and is manufactured by the Swiss Serum and Vaccine Institute (Berne, Switzerland), now Berna Biotech Ltd., CBER/FDA lic. no. 0021. Berna Biotech merged into Crucell N.V. in Oct. 2006, after Crucell acquired it from Acambis (which had acquired the company, but only held on to it for about 3 years).

Vivotif Berna is marketed in the U.S. by Berna Products Corp., formerly the U.S. marketing subsidiary of Berna Biotech, formerly a subsidiary of Acambis plc, now a subsidiary of Crucell, CBER/FDA est. 1841. The vaccine is marketed in Germany and much of Europe by Novartis Vaccines and Diagnostics Ltd. (formerly Chiron Behring GmbH & Co., originally Behringwerke AG).

Manufacture: The vaccine is manufactured using a seed-lot system. The working seed lots represent not more than one subculture from the master seed lot. The final vaccine represents not more than four subcultures from the original vaccine. Master seed lots used in the preparation of working seed lots comply with tests including galactose metabolism, biosynthesis of lipopolysaccharide, serological characteristics, biochemical markers, and cell growth. Galactose metabolism is tested using a spectrophotometric assay, with no activity of the enzyme uridine diphosphate-galactose-4-epimerase found in the cytoplasm of strain Ty21a compared to strain Ty2. To test bio-syn-thesis of lipopolysaccharide, lipopolysaccharides are extracted by a hot-phenol method and examined by size-exclusion chromatography. Strain Ty21a grown in medium free of galactose shows only the rough (R) type of lipopolysaccharide. Serological testing includes showing that Ty21a grown in synthetic medium without galactose does not agglu-ti-nate specific anti-S. typhi O:9 antiserum; whatever the growth conditions, does not agglutinate to S. typhi Vi antiserum; and agglutinates to S. typhi H:d flagellar antiserum. Testing for biochemical markers includes showing that strain Ty21a does not produce hydrogen sulphide on Kligler iron agar. This distinguishes Ty21a from other galactose-epimerase-negative S. typhi strains. Testing for cell growth involves showing that strain Ty21a cells lyse when grown in the presence of 1% galactose.

The bacteria from the working seed lot are multiplied in a preculture, subcultured once, and are cultured in a suitable medium (containing bovine tissue digest, an acid digest of casein, dextrose, and galactose) containing 0.001% galactose at 30˚C for 13-15 hours. The bacteria are harvested and separated by centrifugation. The harvest must be free from contaminating microorganisms, and only a single harvest that complies with the tests including pH, optical density and identity may be lyophilized. The harvest is mixed with stabilizers (lactose and amino acid mixture) and lyophilized by a process that ensures the survival of at least 10% of the bacteria and water content favorable to the stability of the vaccine. No antimicrobial preservative is added to the vaccine. Freeze-dried harvest must comply with the tests for identity, number of live bacteria, and water. The number of live bacteria should be >1 x 1011 live S. typhi strain Ty21a per gram; and water content of the powder should be 1.5-4.0%. The final bulk vaccine is prepared by aseptically mixing one or more freeze-dried harvests with sterile excipient. The final bulk vaccine is packaged under aseptic conditions into gelatin capsules coated with a shell to allow the capsules to resist stomach acid. Each dosage unit contains >4 x 109 live bacteria.

FDA class: Biologic PLA

CBER class: Bacterial Antigens and Vaccines

Approvals: Date = 19891215; first approval, PLA

Indications: [first paragraph of the "Indications and Usage” section from product insert/labeling]:

Vivotif Berna Vaccine is indicated for immunization of adults and children greater than 6 years of age against disease caused by Salmonella typhi. Results from clinical studies indicate that adults and children greater than 6 years of age may be protected against typhoid fever following oral ingestions of 4 doses of Vivotif Berna Vaccine. Immunization (ingestion of all four doses of Vivotif Berna Vaccine) should be completed at least 1 week prior to potential exposure to S. typhi.

Status: Vivotif Berna is marketed in over 50 countries. It was first launched in 1981.

FDA temporarily suspended imports in 1999, because of quality deficiencies in the production process.

Trials: Efficacy in open-label field trials in areas with endemic typhoid fever ranged from 42%-67%. Use of three doses resulted in a 95% decrease in the incidence of typhoid fever during a 3-year field study in over 32,000 Egyptian children. In large field trials in Chile, the vaccine efficacy for subjects aged 15-44 years was ~60%. Prophylactic efficacy has been shown to persist for up to 5 years. Pre-approval trials included challenge studies involving administration of S. typhi to (induction of typhoid fever in) inmate volunteers (an accepted practice at the time). Efficacy has not been studied among persons from areas without endemic disease who travel to disease-endemic regions. Live Ty21a can be shed transiently in the stool of vaccine recipients. However, secondary transmission of vaccine organisms has not been documented. Ty21a is immunogenic even in persons with preexisting antibody titers. As a live vaccine, Ty21a should not be used in immune compromised, e.g., HIV-infected, persons.

Tech. transfer: An exemplary U.S. patent covering aspects of S. typhi strain Ty21a is 3,856,935 assigned to the Swiss Serum and Vaccine Institute and Institut Zug Eforschung der Infektion-kranhelten (Bern, Switzerland), now expired. This patent describes mutation of S. typhi by exposure to ultraviolet light and selection of strains defective in uridine diphos-phoga-lac-tose-4-epimerase and with sharply reduced galacto-kinase and galactose-1-phosphate uridylyltransferase activity, and use for vaccines. Based on time spent in clinical trials and FDA review (under 35 USC §156), the expiration date of this patent was extended from Dec. 24, 1989 to Dec. 24, 1991.

Medical: Four doses are required for primary immunization. One capsule should be taken orally about 1 hour before a meal on days 1, 3, 5 and 7. An optimal booster schedule has not been determined, but for cases of repeated or continuous exposure, the suggested booster regimen is to repeat the primary series every 5 years. A booster dose may be administered every 2 years after the primary dose, if continued or renewed exposure is expected. Capsules should be swallowed whole with water at or below body temperature one hour before eating. Onset of immunity takes about one week, and the primary course of vaccination should be completed a week or more before potential exposure to S. typhi. The vaccine generally provides about 60-70% protection (reduces the incidence of typhoid fever by this amount). Generally, Ty21a produces fewer adverse reactions than injected S. typhi vaccines.

Market: The 2007 Average Wholesale Price (AWP) is $42.85/package of four capsules (Red Book, 2007). This is unchanged since 2004.

Total 2006 sales have been projected by one source to be CHF 20 million [$15.64 million, on 4/20/2007].