美国在2000年宣布麻疹已经在当地得到了根治。去年一年，美国27个州确诊了644例麻疹，创下美国2000年宣布已消灭麻疹疫情以来的新高。今年可能也不会好转，据美国疾病控制与预防中心统计，至本月2日已经有14个州报告了102个病例。

该中心主任弗里登1日警告称，“美国可能会暴发一场大规模的麻疹疫情”。弗里登表示，已经采取强有力的公共卫生措施来甄别患者，但防止麻疹扩散最有效的方法是接种疫苗。弗里登称，很多家长没有给孩子接种疫苗，有些人担心疫苗的安全性，有些人则认为麻疹已经不存在了。

根据CDC统计，麻疹疫苗对于疾病的预防比例为93-97%。麻疹是由麻疹病毒引起的，一种高度传染性呼吸道疾病，其症状包括发热、咳嗽、皮肤出现红色斑丘疹等，严重者可引发肺炎。

病毒的常见并发症包括耳部感染和腹泻，而更严重的并发症包括肺炎(儿童中麻疹相关性死亡最常见原因)，脑炎(可引起抽搐，耳聋和脑损伤)。

在1912年，麻疹首次成为“全国法定报告”(麻疹首次成为“全国法定报告疾病”)性疾病，医疗保健提供者必须报告所有确诊病例。在接下来的10年中，每年大约有6000例麻疹相关死亡事件发生。

在20世纪50年代，在美国每年大约300-400万人感染麻疹病毒，大约48000人住院， 400-500人死于该病毒。在15岁之前，几乎所有孩子均感染麻疹，每年大约4000人发展麻疹相关性脑炎。

Are ongoing concerns about vaccine safety to blame for the measles epidemic?

In 2000, measles was declared eliminated in the US. But last year saw a record number of measles cases since - 644 over 27 US states. This year is unlikely to be any better, with 102 cases reported so far. In this spotlight, we look at whether ongoing concerns surrounding vaccination safety are behind the measles epidemic.

According to the CDC, the MMR vaccine is 93-97% effective at preventing measles.Measles is a highly contagious respiratory disease caused by infection with the morbillivirus. Onset of the disease usually begins with a fever, cough, inflamed eyes, runny nose and sore throat, before a red, blotchy rash appears all over the body.

Common complications of the virus include ear infections and diarrhea, while more severe complications include pneumonia - the most common cause of measles-related death in children, and swelling of the brain, known as encephalitis, which can cause convulsions, deafness and brain damage.

Measles first became a "nationally notifiable" disease - a condition in which health care providers had to report all diagnosed cases - in the US in 1912. Over the following decade, there were around 6,000 measles-related deaths in the country each year.

In the 1950s, around 3-4 million people in the US became infected with measles annually, with around 48,000 hospitalizations and 400-500 deaths from the virus each year. Almost all children contracted measles by the age of 15, and around 4,000 people developed measles-related encephalitis each year.