Uriel Katz MD, PhD, Eli Schwartz MD, PhD
DOI: 385 First published online: 1 November 2006

Response to Letters:

In response to the issues raised by Dr. Freedman and Dr. Rombo in their letters regarding our editorial entitled “Caring for the Caregivers,” 1 the editorial was not written to discuss the current situation of cholera vaccine, but rather to discuss the need for it, for these types of missions. Indeed, the current situation is that the oral vaccine WC/rBS (Dukoral, SBL Vaccine AB, Stockholm, Sweden) is available only in certain markets (mainly in Europe). The other oral vaccine, CVD 103‐HgR (Orochol, Berna Biotech, Berne, Switzerland) is no longer produced, and also the parenteral vaccine (inactivated whole cell Vibrio cholera strains), although licensed, is no longer available. 2

The short‐term efficacy of the oral vaccine WC/rBS has been found to be between 60 and 85% after at least two doses in endemic populations. This efficacy is not necessarily reproducible in a nonimmune population, as demonstrated by one study that was done in a nonimmune population of 11 volunteers showing only moderate efficacy (64%) after three doses. 3

As mentioned by Dr. Rombo, protection appears some 8 days after the completion of vaccination, that is to say after receiving two doses 1 week apart. Therefore, the vaccination is useless for individuals on a mission who will be exposed within a short period of time (36 hours in our case) and scheduled to be out of the endemic area within 2 weeks, as was in our case.

The estimated clinical cholera attack rate among travelers is in a magnitude of two to three cases per million. Furthermore, to the best of our knowledge, no cholera cases have been reported among health care workers, probably due to higher awareness and safer practices. Dr. Rombo’s statement, “vaccination is a matter of reducing risks” is absolutely true, however, in this case, where the risk approximates zero as long as hygienic measures are implemented, to what extent can the risk be further reduced?

In sum, the lack of vaccine availability in many countries, the general short notice of rescue missions to these areas, the moderate efficacy of the vaccine, the almost null attack rates to medical personal serving affected populations, and the easy way of preventing the disease by simple universal hygienic measures makes the vaccine an unimportant tool.

Strong recommendations for the need of the vaccine for caregivers may give them a false sense of security when the vaccine is given. Furthermore, protection is partial and does not cover all cholera strains. In addition, emphasizing the need for vaccine for caregivers may give them a false sense of insecurity if vaccine is not given or could dissuade some of them from going on these missions when vaccine is not available.

As mentioned, the chance of contracting the disease by caregivers is apparently very low. However, even if the disease were acquired, a short course of antibiotics, such as quinilones or single dose of azithromycin, is highly effective. 4

Would cholera vaccination be advisable in other situations in which a longer exposure is scheduled? We agree that it might be a legitimate choice. In our case, we would prefer to stick with universal hygienic measures due to a high efficacy of protection and to the fact that transmission of cholera to medical personnel has largely not been reported.


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