Читать книгу Vaccines For Dummies - Sharon Perkins - Страница 25

Type B causes illness similar to Type A. Type B doesn’t have subtypes but has two main lineages. It isn’t as common a cause of illness as type A is. Generally, type B causes just 25 percent of influenza illnesses during the year. It doesn’t change by shift, only by drift, so it doesn’t have the same sudden changes that throw off our immune system. Type B also isn’t known to infect animals, except for seals, so we don’t have to deal with lineages from animals. Type B can still cause serious illness, including pneumonia, and can be fatal in some cases. Vaccines used to include just one B influenza virus, but now most include two.