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Ask Well: How Long Does a Flu Shot Last?
By Donald G. Mcneil Jr.
Flu vaccines are different from vaccines for other diseases, such as measles, because they are given every year. The chief reason, experts say, is not that the vaccine wears off, but that flu viruses mutate so fast as they move around the world. The flu shot or nasal mist – which now may contain up to four separate vaccines against four separate influenza viruses – must be reformulated every year in an effort to match the most common circulating strains. How long your own flu shot lasts depends on how powerfully your own immune system reacts to it, said Dr. John J. Treanor, a vaccine expert at the University of Rochester medical school. In a young, healthy person, protection might last for years, even as circulating flu strains change. Conversely, he said, there is some debate about whether older people or those with compromised immune systems ought to get two flu shots per season, since a shot they got in October may wear off by March or April. “It’s a controversial question, and there’s not a lot of direct data on it,” Dr. Treanor said. The need for repeat vaccinations is different for each disease, he added. Two measles shots in childhood usually give lifelong protection. Tetanus shots should be repeated every 10 years or so. Pertussis, or whooping cough, shots are moving in that direction as well, since a new vaccine with fewer side effects that was introduced the 1990s gives shorter-lived protection.
(Adaptado de: http://well.blogs.nytimes.com/2014/01/17/ask-well-how-long-does-a-flu-shot-last/?php=true&type=blogs&r=0. Acesso em: 20 fev. 2014.)
Com relação à vacina contra gripe, atribua V (verdadeiro) ou F (falso) às afirmativas a seguir.
( ) A duração da vacina depende da reação do sistema imunológico de cada indivíduo.
( ) A vacina contra gripe tem efeito tão duradouro quanto o da vacina contra tétano.
( ) Cada dose de vacina contra gripe pode conter até quatro diferentes vírus da doença.
( ) Especialistas discordam quanto à necessidade de inoculação da vacina contra gripe em idosos.
( ) Pessoas imunodeprimidas devem tomar a vacina contra gripe duas vezes no ano: março e outubro.
Assinale a alternativa que contém, de cima para baixo, a sequência correta.
