Chicken pox is a highly communicable disease. it may be transmitted by direct contact with a person infected with the varicella-zoster virus (vzv). the typical incubation time is between 10 to 20 days. a boy started school 2 weeks after showing symptoms of chicken pox including mild fever, skin rash, and fluid-filled blisters. one month after the boy returned to school, none of his classmates had been infected by vzv. what was the main reason?

Someone who had it before gave that symtom to him

Explanation:

answer; i do believe that the correct answer is ( portal of exit in the chain of transmission); good luck

to prevent people from getting the ebola virus, countries around the world paid to doctors develop a new vaccine. now that the vaccine has been made, doctors will need to experiment on a large number of people to find out if it works safely.

what is the greatest limitation that scientists are dealing with as they try to figure out how to experiment with the ebola vaccine?

meditation is a practice of sitting still and quiet for minutes or even hours. it has been practiced for thousands of years and is even a part of religious practices for some people. carefully controlled, repeated measurements of brain activity have shown that meditation does increase certain chemicals in the brain and even grows the part of the brain that people connect with their current surroundings and activities.

are claims about the effects of meditation most likely scientific or pseudoscientific?

not pseudoscientific, because people have made claims about it but scientific observations have not been made