Effect of a single tetanus-diphtheria vaccine dose on the immunity of elderly people in São Paulo, Brazil

Abstract

Epidemiological data regarding tetanus and diphtheria immunity in elderly people in Brazil are scarce. During the First National Immunization Campaign for the Elderly in Brazil in April 1999, 98 individuals (median age: 84 years) received one tetanus-dyphtheria (Td) vaccine dose (Butantan Institute, lot number 9808079/G). Inclusion criteria were elderly individuals without a history of severe immunosuppressive disease, acute infectious disease or use of immunomodulators. Blood samples were collected immediately before the vaccine and 30 days later. Serum was separated and stored at -20 o C until analysis. Tetanus and diphtheria antibodies were measured by the double-antigen ELISA test. Tetanus and diphtheria antibody concentrations lower than 0.01 IU/mL were considered to indicate the absence of protection, between 0.01 and 0.09 IU/mL were considered to indicate basic immunity, and values of 0.1 IU/mL or higher were considered to indicate full protection. Before vaccination, 18% of the individuals were susceptible to diphtheria and 94% were susceptible to tetanus. After one Td dose, 78% became fully immune to diphtheria, 13% attained basic immunity, and 9% were still susceptible to the disease. In contrast, 79% remained susceptible to tetanus, 4% had basic immunity and 17% were fully immune. Although one Td dose increases immunity to diphtheria in many elderly people who live in Brazil, a complete vaccination series appears to be necessary for the prevention of tetanus.

An Epidemiological Profile of Accidental Tetanus Cases in a Referral Hospital, 2007-2013

“…Also, the elderly population was affected by the disease significantly, reiterating the results found in other studies [2,4,9]. The risk of major involvement in this group is justified by the decrease in immunity, as levels of tetanus protective antibodies decrease with advancing age [12]. Moreover, over the years, the human being loses psychomotor capacity and perceptions of space, being more prone to accidents [13].…”

Tendência temporal do tétano acidental no período de 1981 a 2004 em Pernambuco com avaliação do impacto da assistência em unidade de terapia intensiva sobre a letalidade

“…Os níveis protetores de anticorpos para o tétano decrescem com o avançar da idade 15 24 . Weckx e cols demonstraram em trabalho recente, através da análise do nível sérico da antitoxina, que 94% dos idosos eram suscetíveis ao tétano, e que uma única dose do toxóide tetânico não era capaz de imunizar adequadamente este grupo 24 . Uma série completa de vacinação antitetânica parece, portanto, ser necessária para a prevenção do tétano nessa faixa etária.…”

Prevalence of diphtheria and tetanus antibodies and circulation of Corynebacterium diphtheriae in São Paulo, Brazil

“…Recent studies assessing diphtheria and tetanus antibody levels have been performed in Brazil, but most of them included specific population or age groups (8,14,16). It can be argued that the present study population may not be representative of São Paulo city.…”

“…In 1999 a National Influenza, Pneumococcus, Tetanus, and Diphtheria Vaccination Campaign for the Elderly was launched in Brazil, and has been continuing every year (7,15). It is probable that, for some elderly people, the Td vaccine acted as a booster for diphtheria even though it was part of primary immunization for tetanus (16).…”