In their letter, Dr. Arya and Dr. Agarwal raise relevant points concerning the importance of the cold chain for the conservation of the measles vaccine, which are also valid for other vaccines. Fundamentally, the efficacy of each vaccine is ensured by its storage at ideal temperatures, from the moment of production until being used in the population (1, 2).
In our study (3) the vaccines used were donated by the three laboratories that produced themInstitute Pasteur Merieux, Merck-Sharp-Dohme, and Serum Institute of Indiaand they were shipped directly to us. All the vaccines were tested by the Brazilian National Institute for Quality Control in Health (Instituto Nacional de Controle de Qualidade em Saúde) before being administered, and their potency was verified. These vaccine strains were not the same as those used by the Brazilian National Immunization Program (Programa Nacional de Imunizações) and mentioned in the letter by Arya and Agarwal.
With respect to the logistics of the study, the storage, handling, and administration of the vaccines were controlled variables. We followed the guidelines recommended by Brazil's National Health Foundation (Fundação Nacional de Saúde), as described in their manual for the cold chain (4). The vaccines were administered immediately after being reconstituted, during the winter, which in southern Brazil is characterized by low temperatures (average 10 °C).
It is also important to underscore that in Brazil the last confirmed case of measles occurred in March of 2002 and that it was imported from Japan (5). We do not have any reports of autochthonous cases thanks to the work carried out by the National Immunization Program through its vaccination strategies, which have received worldwide recognition.
Taking these aspects into consideration, we believe that the data concerning the reactogenicity of the three measles-mumps-rubella combination vaccines evaluated in our study are in essence related to the strains that protect against mumps.
Boaventura Antonio dos Santos
Hospital de Clínicas de Porto Alegre
Rua Ramiro Barcelos, 2350
Porto Alegre, Rio Grande do Sul, Brazil
1. Murray-Perrault K, Naus M. Vaccine potency: the importance of maintaining the vaccine cold chain. Vaccines children and practice. 2001;4(1):1722.
2. Bell KN, Hogue CJR, Manning C, Kendal A. Risk factors for improper vaccine storage and handling in private office providers. Pediatrics 2001;107(6):8589.
3. Santos BA dos, Ranieri TS, Bercini M, Schermann MT, Famer S, Mohrdieck R. An evaluation of the adverse reaction potential of three measles-mumps-rubella combination vaccines. Rev Panam Salud Publica 2002;12(4):240246.
4. Brasil, Fundação Nacional de Saúde, Programa Nacional de Imunizações. Manual de rede de frio. 3rd ed. Brasília; FNS: 2001.
5. Brasil, Fundação Nacional de Saúde. Guia de vigilância epidemiológica. Vol. II. Brasília; FNS: 2002.