The government has ordered 195 million doses of vaccine, 45 million of which will be delivered by mid - October. But because most people lack prior immunity to the new H1N1 virus, officials expect that two injections will probably be necessary, spaced three weeks apart. Clinical trials are currently underway to confirm whether two shots are actually needed and to determine the optimal dose. Resuhs from those trials will be available in late September or early October. But even after receiving the vaccine, a person will take at least five weeks to develop full immunity.
Two injections of the vaccine will probably necessary because.

单项选择题Your health can suffer simply from fear of losing your job, says Sarah Burgard, a sociologist at the University of Michigan. After crunching data from two large national surveys, she concluded that chronic job insecurity over a two--year period rivals the anxiety of a job loss or a major illness. Burgard adjusted her data for what psychologists call neuroticism and found that even people who aren’t typically worriers report worse health when they believe their jobs are in danger. Fears of poor job prospects may have similar consequences. When Swedish researchers asked 21 - year - olds about their health during a recession, they reported more problems than a comparison group during a boom. According to Sarah Burgard, people’s health tend to get worse when

单项选择题A co - worker of mine recently recommended to do some research online before making my next purchase. As an elementary school teacher with a modest salary and a sizeable mortgage, cost was a major concern. While searching the Web I found a few online teeth whitening companies giving away free trials where you only had to pay a few dollars for shipping. I ordered two products, Dazzle White and Total White, both of which had 9 10 ratings and positive feedback from all users. After using the first product the results were noticeable, but after following with the second product I had a celebrity white smile. I’m far from a medical expert, but it appears that each product focused on DIFFERENT parts of the problem and that the second one put the whitening effect into overdrive. By using them both in a row I had absolutely unbelievable results. I can’t believe companies are practically giving these products away! What is the economic status of the elementary school teacher