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I've come to collect a parcel http://yuvututube.fun/ yuvutu tube videos For some diseases, such as mumps, herd immunity can drop to as low as about 75 percent and still offer wider protection. But other diseases, such as the highly contagious measles or pertussis, known as whooping cough, require collective immunity of up to 94 percent to keep everyone safe, according to the CDC. |
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