Use of oral typhoid vaccine strain Ty21a in a New York state travel immunization facility.

One hundred fifty-seven travelers who received the new oral typhoid vaccine strain Ty21a between April 1990 and February 1992 were surveyed by questionnaire to assess compliance and toxicity. The four-dose vaccine should be taken every other day before meals, and kept refrigerated between doses. Noncompliance with one or more of these instructions was seen in approximately 30% of travelers. Thirty-four (21.6%) took one or more doses after meals, 13 (8.3%) did not take all four doses, 10 (6.4%) failed to take the dose every other day, and five (3.2%) did not keep the vaccine refrigerated. The vaccine was well-tolerated and only 14 (8.9%) had one or more minor side effects. Of 59 (38%) who had received injectable typhoid vaccine previously, all preferred oral versus injectable vaccine, and reported moderate-to-severe side effects with the injectable form. Until a single-dose, oral typhoid vaccine is available, Ty21a is an attractive option. To achieve maximum efficacy, the importance of compliance should be emphasized.