Vaccinated people may transmit whooping cough
Whooping cough may be transmitted by healthy people who are vaccinated against whooping cough. In a smaller study by the US drug agency FDA, scientists examined the transmission pathway of whooping cough more closely. No whooping cough diseases were observed in the monkeys treated with the common vaccines, but the vaccinated animals apparently transmit the pathogen to their conspecifics. According to the researchers, this can be the reason for the current widespread spread of whooping cough diseases in the USA.
The US authorities registered about 42,000 whooping cough infections last year, despite the fact that the majority of the population is vaccinated against them. There have not been that many in the past 50 years, according to the FDA study, which was published in the journal "Proceedings" of the US Academy of Sciences ("PNAS"). For Tod J. Merkel and his colleagues from the FDA, the development of an improved vaccine against whooping cough is therefore a priority.
Significance of the study For the German experts at the Paul Ehrlich Institute (PEI) in Langen, Hesse, the significance of this FDA study is "low" due to the small number of test animals. The study was unable to show that the unvaccinated monkeys really got sick after the transmission of the pathogen by vaccinated monkeys, PEI President Klaus Cichutek said. For him, the results are no reason to change the vaccination recommendations currently applicable in Germany.
According to the Robert Koch Institute (RKI), 5,438 people fell ill with whooping cough caused by "Bordetella pertussis" bacteria in the new federal states last year. Compared to the same period last year, the number has almost halved. Since March 2013, the disease has had to be reported in the old federal states. Vaccination against whooping cough had already started in Germany in 1960. Initially, the so-called whole germ vaccine often had severe side effects. The advantage of these vaccines compared to others is their longer effectiveness, says Wiebke Hellenbrand from the RKI. It was only in the mid-1990s that acellular vaccines against whooping cough were used in Germany.
In their investigations, the US researchers had treated small groups of monkeys a few months old several times with whole germ or acellular vaccines. It was shown that only the unvaccinated animals fell ill. However, it took about three weeks until no more pathogens were found in the vaccinated animals.
The animals that had been given acellular vaccines were only bacteria-free after up to six weeks and then transmitted the pathogen to other animals. To the knowledge of the PEI, there is currently no vaccine in development in the EU that would guarantee longer and more comprehensive vaccination protection. "We cannot currently contain whooping cough completely, but we can control the number of cases in which we further improve vaccination rates, particularly among adolescents and adults," says RKI expert Hellenbrand. People who have close contact with infants should be vaccinated. Vaccination protection must be renewed regularly, at the latest after ten years. (fr)
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