Tetanus, diphtheria and whooping cough are covered by various combination vaccines in Australia. While part of the routine childhood immunisation schedule, recommended coverage for adults becomes more complex, with varying schemes and rules governing who gets which combination and when. For most adults these vaccines are not covered by Medicare. With this complex framework in mind, researchers wanted to delve into the vaccine coverage of these conditions over time. They looked at data from the Australian Immunisation Register (AIR) from the beginning of 2024, capturing coverage of tetanus, whooping cough and diphtheria in adults aged 50 onwards (divided into age brackets of 50-64, 65-74, 75-84, 85+).
The research found significant rates of under-vaccination in older Australians, with about a third of people over 50 having appropriate coverage for tetanus and diphtheria, and only a fifth for whooping cough. In those covered for tetanus, the most recent vaccine for two thirds of people was dTPa, and a third had dT. Of everyone captured in the study, rates of coverage for tetanus and diphtheria had minimal variation with age, but the proportion of whooping cough coverage consistently declined with age, with only 13.5 per cent of those over 85 up to date. The authors acknowledge that the data may underestimate rates of vaccination, as the AIR only began capturing adult vaccinations in 2016 and reporting these vaccinations to the AIR is not mandatory.
The range of combination vaccines for diphtheria, tetanus and whooping cough means that appropriate vaccine coverage for each disease can make it difficult for patients to keep track of whether their vaccines are up to date. While the aim of routine dTpa boosters in older people is primarily to protect against whooping cough, presentations to emergency for wounds would contribute to coverage rates being higher for diphtheria and tetanus than whooping cough. The authors suggest this means that whooping cough coverage is less comprehensive than it should be. The recommendations for diphtheria, tetanus and whooping cough vaccination are relatively complex, with the study noting practitioners are often not up to date with the recommended schedule.
Furthermore, this research is published at a time when Australians are being urged to get the whooping cough vaccination as infections rise more than tenfold in a year. At the time of writing more than 26,700 cases reported so far in 2024, compared with 2,451 cases for all of 2023.
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