Hi Nadya! I like the sentences you made, they just have some small mistakes.
Let's check them one by one.
1. 欢乐的心情感染了周围的人们。 It is actually a correct and great sentence!
2. 他是急诊出诊大夫。Also correct!
3. 他怎么得减少个人接触？Here are two words I'm quite confused with, the first one is "得"，do you mean "have to, need to" or "How can he……" here? and "个人接触" do you mean "personal contact"? Hope you can provide the original meaning of this sentence.
4. 几月的放假帮了他恢复健康。 Let's see several mistakes you made in this sentence: 1) “几月” is a point of time and it literally means "which month?" (e.g. 你几月回中国？) Obviously you want to say "a couple of months" here, so it should be "几个月"。 2）Because there is a "放（to put, to release）" in “放假” , "放假" is a verb rather than a noun. you can say "几个月的假期" which means "a few months vacation". 3) it's ok if you use "帮" in this sentence, but I would suggest you to use "让 （to let, to ask, to make）" 4）"了" in this case is a indicator for completiom of an activity, in your sentence, here are two verbs: "帮" and "恢复"，since the action "help" and "recover" have been both completed, so you should put "了" after the second verb, which is "恢复"。 To conclude, the sentence number three "几个月的假期让他恢复了健康。"
5. 我们要搬家的地区是不是危害的？ Only one mistake in this sentence. The word "危害" is a verb, means endanger or damage, for example, "抽烟危害健康"。Your sentence is more like "危险"，an adj means dangerous. So change "危害" to "危险" then this sentence is correct.
I hope you like my answer and I'm looking forward to getting more information about the third sentence.