How common are measles deaths in the United States as vaccination rates fall?

Centers for Disease Control

A fourth person with measles has died in Pennsylvania, the state announced Tuesday — marking the first time in decades the United States has recorded so many deaths in a single year.

Measles deaths have been extremely rare in the United States because most people are protected by a highly effective vaccine. But as vaccination rates decline nationally and measles cases rise globally, experts say the death toll from measles may continue to grow in the United States this year and beyond.

The last year with at least four measles deaths in the United States was 1992.

Until the recent resurgence in cases, the United States went several years without any measles deaths.

Last year, there were three measles deaths, and before then, the last measles death was in 2015 , when a Washington state woman died. Before then, the United States hadn’t had a measles death since 2003.

BSIP/UIG via Getty Images

Pennsylvania reports fourth measles-related death, the most in US in decades

This year was already the second record-breaking year in a row for measles cases. As of July, the country has recorded more measles cases than in any other year since 1991.

Before the vaccine became available in 1963, measles sickened 3 million to 4 million people and led to about 500 deaths every year in the United States.

Measles was declared eliminated from the United States in 2000, but recent outbreaks mean that status will be reassessed in November.

In a Tuesday Senate hearing, the nominee for deputy secretary of the US Department of Health and Human Services, Chris Klomp, appeared to acknowledge the US had lost its elimination status, and endorsed measles vaccination strongly as the best way to regain it.

“Unquestionably, the MMR [measles, mumps, rubella] vaccine is the single most effective public health tool that we have against measles,” Klomp, a former healthcare executive, told the Senate Finance Committee in the first of two confirmation hearings over two days. “It’s 97% effective after two doses to preventing transmission, and is the single best thing that we can do to eradicate and establish our exemption from measles again.”

Measles deaths are much more common in low-income countries with weaker health infrastructure than in the United States or similar countries.

Globally, an estimated 95,000 people died from measles in 2024, according to the World Health Organization . Ninety-five percent of those deaths were in low-income countries.

Measles is considered the most contagious infectious disease known to humans; up to 9 out of 10 unvaccinated people who come in contact with an infected person will catch the virus. Vaccinations have proven highly successful, preventing an estimated 59 million deaths from 2000 to 2024, WHO said .

Before widespread vaccination, measles caused an estimated 2.6 million deaths globally each year.

Other high-income countries have seen record numbers of measles cases in recent years as well; last year, Canada reported 5,462 measles cases and two deaths. The country lost its elimination status because of sustained transmission for more than a year, a fact HHS nominee Klomp pointed out.

Many countries have lost their elimination status, Klomp told Sen. Ron Wyden, a Democrat from Oregon and the ranking member of the finance committee. “We’ve seen vaccination rates dropping all over the world, not just the United States,” Klomp said.

Nonetheless, Klomp’s unequivocal embrace of the MMR vaccine contrasted with the mixed messaging from his boss, HHS Secretary Robert F. Kennedy Jr., a longtime vaccine critic who has downplayed the seriousness of measles.

Trump’s new CDC Director excludes PA deaths from measles update

Globally, measles typically kills nearly 3 out of every 1,000 people who get sick; in the United States, it’s about 1 in 1,000, research shows .

As of this week, Pennsylvania had counted at least 693 measles cases, 133 hospitalizations and four deaths, according to the Pennsylvania health department .

The official tally is likely an undercount. Measles cases are often unreported when people have milder symptoms and don’t see a doctor who would report the case.

Pennsylvania’s death toll is “on the high side,” said Johns Hopkins University Professor Dr. William Moss, an epidemiologist who has studied measles for years.

Moss believes the higher number of deaths in Pennsylvania “reflects the fact that these infections occurred in individuals, except for the 18-year-old, with underlying risk factors for severe illness and mortality, particularly the two infants.”

One infant who died had a ruptured spleen and died shortly after birth.

The other infant had Amish microcephaly, a rare and severe genetic disorder that causes a small head and underdeveloped brain and leaves children with little chance of surviving beyond a couple of months, Moss said.

The 40-year-old woman who died had chronic obstructive pulmonary disease, which increased her risk for a severe lung infection from measles.

“They’re all tragic cases, all unvaccinated cases, but kind of unique in their underlying risk factors for severe measles,” Moss said.

The Mifflin County, Pennsylvania, coroner said this week that an 18-year-old with measles died from acute disseminated encephalomyelitis, known as ADEM.

Acute disseminated encephalomyelitis is a severe neurological complication of measles that triggers rapid inflammation and swelling in the brain and spinal cord. It develops in about 1 in 1,000 measles cases.

“It’s just a relatively rare, but known complication of measles that can occur in anyone, even otherwise healthy individuals,” Moss said.

Neither Moss nor Dr. David Margolius, director of the Cleveland Department of Health, believes the virus has mutated to become more deadly.

There may be more deaths because there are more cases and fewer people are getting vaccinated, Margolius said.

“So it’s been given a door in, and it’s taken advantage and the virus has spread across many populations across the world,” Margolius said.

Dr. Oz: MMR vaccine is not ‘lethal’

Joe Raedle/Getty Images

There is no specific treatment for measles, so prevention is the best way to reduce risk of serious illness or death. The measles vaccine is highly effective, providing 97% protection for most people.

“It’s not perfect and we have a two-dose vaccine schedule for a reason,” Moss said. “Not everyone responds to the first dose.”

The risk of death from measles for vaccinated people is “very low, unless you’re immunosuppressed in some way,” Moss said.

Measles, mumps and rubella protection are combined into one vaccine administered when a baby is between 12 to 15 months old. Children get a second dose between ages 4 and 6. For most people, protection provided by the vaccine lasts a lifetime.

Measles can be serious for anyone at any age, but some groups are more at risk of serious complications, including:

Children younger than 5

Adults older than 20

People who are pregnant

People with weakened immune systems from conditions such as HIV or leukemia

Dr. Paul Offit: ‘No,’ the US cannot still claim to have measles elimination status

Measles is well known for its rash, fever and cough, but it can also cause seizures, blindness, deafness and permanent lung damage.

Measles can also weaken the central nervous system and immune system, resulting in serious disease or death years later.

The measles virus can also essentially wipe out the body’s previous immune memory, making people vulnerable to other dangerous infections, even long after they recover from the initial infection.

Subacute sclerosing panencephalitis, or SSPE, is a rare but fatal central nervous system disease that can develop seven to 10 years after a person is infected and seems to have recovered.

Before vaccination was widely available, about 1,000 people developed chronic disability from acute encephalitis caused by measles annually, according to the CDC .

CNN’s Meg Tirrell contributed to this report.

美国疾病控制与预防中心

宾夕法尼亚州周二宣布，该州第四名麻疹患者死亡——这是几十年来美国首次在一年内记录到如此多的死亡病例。

在美国，麻疹死亡病例极其罕见，因为大多数人都接种了高效的疫苗。但随着全美疫苗接种率下降和全球麻疹病例增加，专家表示，今年及以后，美国的麻疹死亡人数可能会继续上升。

美国上一次出现至少四例麻疹死亡病例是在 1992 年。

在最近病例再次激增之前，美国曾连续几年没有出现麻疹死亡病例。

去年，美国有三例麻疹死亡病例；在此之前，上一次出现麻疹死亡病例是在2015年，当时一名华盛顿州妇女去世。再往前，美国自2003年以来就没有出现过麻疹死亡病例。

图片来自 Getty Images/BSIP/UIG

宾夕法尼亚州报告了第四例麻疹相关死亡病例，这是美国几十年来最高的死亡人数。

今年已经是麻疹病例连续第二年创下纪录。截至7月，该国记录的麻疹病例数已超过1991年以来的任何一年。

在 1963 年疫苗问世之前，麻疹每年在美国造成 300 万至 400 万人患病，并导致约 500 人死亡。

2000 年，美国宣布消除麻疹，但最近爆发的疫情意味着这一状况将在 11 月重新评估。

在周二的参议院听证会上，美国卫生与公众服务部副部长提名人克里斯·克隆普似乎承认美国已经失去了消除麻疹的地位，并强烈支持接种麻疹疫苗，认为这是重新获得该地位的最佳途径。

“毫无疑问，麻疹、腮腺炎、风疹 (MMR) 疫苗是我们对抗麻疹最有效的公共卫生工具，”克洛普（Klomp）说道。他曾是一名医疗保健高管，在为期两天的两次确认听证会的第一场听证会上，他表示，“接种两剂后，其预防传播的有效率高达97%，是我们根除麻疹并再次确立我国对麻疹的豁免权的最佳途径。”

与美国或类似国家相比，低收入、卫生基础设施薄弱的国家中，麻疹死亡病例要常见得多。

据世界卫生组织估计，2024年全球将有9.5万人死于麻疹。其中95%的死亡病例发生在低收入国家。

麻疹被认为是人类已知最具传染性的传染病；十个未接种疫苗的人中，高达九个会因接触感染者而感染该病毒。世界卫生组织表示，疫苗接种已被证明非常成功，预计在2000年至2024年间可预防5900万人死亡。

在广泛接种疫苗之前，麻疹每年在全球造成约 260 万人死亡。

近年来，其他高收入国家的麻疹病例数量也屡创新高；去年，加拿大报告了5462例麻疹病例和2例死亡。由于麻疹持续传播一年多，加拿大失去了消除麻疹国家的地位，美国卫生与公众服务部提名人克隆普也指出了这一点。

克隆普告诉参议员罗恩·怀登（Ron Wyden），许多国家已经失去了消除新冠疫情的地位。怀登是来自俄勒冈州的民主党人，也是参议院财政委员会的资深成员。“我们看到世界各地的疫苗接种率都在下降，不仅仅是美国，”克隆普说。

尽管如此，克隆普对麻疹、腮腺炎、风疹疫苗的明确支持，与他的上司——美国卫生与公众服务部部长小罗伯特·F·肯尼迪——的矛盾态度形成了鲜明对比。小罗伯特·F·肯尼迪长期以来一直批评疫苗，并淡化了麻疹的严重性。

特朗普新任命的疾控中心主任将宾夕法尼亚州的死亡病例排除在麻疹死亡病例统计之外。

研究表明，在全球范围内，麻疹通常会导致每 1000 名患者中约 3 人死亡；在美国，这一数字约为千分之一。

据宾夕法尼亚州卫生部门统计，截至本周，宾夕法尼亚州已累计报告至少 693 例麻疹病例，133 例住院病例和 4 例死亡病例。

官方统计数据可能偏低。麻疹病例往往未被上报，因为患者症状较轻，且未就医，医生也就不会上报病例。

约翰·霍普金斯大学教授、流行病学家威廉·莫斯博士表示，宾夕法尼亚州的死亡人数“偏高”。莫斯博士多年来一直研究麻疹。

莫斯认为，宾夕法尼亚州较高的死亡人数“反映出，除了那名 18 岁的年轻人之外，其他感染者都存在罹患重病和死亡的潜在风险因素，尤其是那两名婴儿。”

其中一名夭折的婴儿脾脏破裂，出生后不久便夭折了。

莫斯说，另一名婴儿患有阿米什小头畸形症，这是一种罕见且严重的遗传性疾病，会导致头部较小、大脑发育不全，使患儿几乎没有机会活过几个月。

这位40岁的死者患有慢性阻塞性肺病，这增加了她感染麻疹后发生严重肺部感染的风险。

“这些都是悲剧病例，都是未接种疫苗的病例，但它们在罹患重症麻疹的潜在风险因素方面却有些独特，”莫斯说。

宾夕法尼亚州米夫林县验尸官本周表示，一名患有麻疹的 18 岁青年死于急性播散性脑脊髓炎（ADEM）。

急性播散性脑脊髓炎是麻疹的一种严重神经系统并发症，会导致脑和脊髓迅速发生炎症和肿胀。大约每1000例麻疹病例中就有1例会发生这种情况。

“这只是麻疹的一种相对罕见但已知的并发症，任何人都有可能患上，即使是原本健康的人也可能发生，”莫斯说。

莫斯和克利夫兰卫生局局长戴维·马戈利乌斯博士都不认为该病毒已经变异，变得更致命。

马戈利乌斯说，由于病例增多而接种疫苗的人减少，死亡人数可能会增加。

“所以病毒有了入侵的机会，并利用了这一点，在世界各地的许多人群中传播开来，”马戈利乌斯说。

奥兹医生：麻疹、腮腺炎、风疹疫苗并非“致命”

乔·雷德尔/盖蒂图片社

目前尚无针对麻疹的特效药，因此预防是降低重症或死亡风险的最佳途径。麻疹疫苗非常有效，可为大多数人提供97%的保护。

“疫苗并不完美，我们采用两剂接种方案是有原因的，”莫斯说。“并非每个人都对第一剂疫苗有反应。”

莫斯说，接种过疫苗的人死于麻疹的风险“非常低，除非你的免疫系统受到某种抑制”。

麻疹、腮腺炎和风疹的保护作用被整合到一种疫苗中，在婴儿12至15个月大时接种。儿童在4至6岁之间接种第二剂。对于大多数人来说，疫苗提供的保护可以持续终生。

麻疹对任何年龄段的人都可能很严重，但某些人群更容易出现严重并发症，包括：

5岁以下儿童

20岁以上的成年人

怀孕的人

因艾滋病或白血病等疾病导致免疫系统受损的人

保罗·奥菲特博士：“不”，美国仍然不能声称已消除麻疹。

麻疹以皮疹、发烧和咳嗽而闻名，但它也可能导致癫痫、失明、耳聋和永久性肺损伤。

麻疹还会削弱中枢神经系统和免疫系统，导致多年后出现严重疾病甚至死亡。

麻疹病毒还会彻底清除人体先前的免疫记忆，使人们即使在从最初的感染中康复很久之后，仍然容易感染其他危险的疾病。

亚急性硬化性全脑炎（SSPE）是一种罕见但致命的中枢神经系统疾病，可在感染后 7 至 10 年内发生，即使患者看似已经康复。

据美国疾病控制与预防中心 (CDC) 称，在疫苗广泛普及之前，每年约有 1000 人因麻疹引起的急性脑炎而患上慢性残疾。

CNN的梅格·蒂雷尔对本报道亦有贡献。