Recent surge in cases worldwide blamed on plunging vaccination rates
The sparsely populated Pacific island nation of Samoa is the latest victim of a resurgence of measles, a highly contagious disease that has been making a comeback around the world since 2017.
So far this year, outbreaks have surfaced in Africa, Asia, North America and Europe, winding back the clock after decades of progress in eliminating the virus. The number of cases in 2019 marks the highest since 2006.
According to the World Health Organization, or WHO, last year there were more than 9.7 million cases of measles and 142,300 deaths globally. This year, the number of cases in the first three months quadrupled from the same period in 2018.
By mid-December, the outbreak in Samoa had killed at least 72 people, mostly children, and almost 5,000 cases had been recorded, incomplete local statistics show. The government had declared an outbreak on Oct 16, followed by a state of emergency on Nov 15.
The situation was made worse by a fall in vaccination rates in Samoa, from 80 percent in 2015 to just 34 percent last year. The vaccination rate dropped sharply in 2018 when two children died after being given incorrectly mixed vaccines. The incident raised fears about vaccine safety, even though an inquiry found the issue was linked to human error.
“Such outbreaks can lead to diseases and deaths that should be totally preventable. The large number of measles cases can sometimes interrupt the normal social order like schools closing and such,” said Xu Fujie, an expert in epidemiology and a public health professor from Zhejiang University. “Measles is highly contagious and can be easily transmitted from person to person” via airborne droplets and other means.
A WHO spokesperson said that there were outbreaks currently in Samoa, Tonga, Fiji and American Samoa. A higher incidence of cases has also been reported across the Asia Pacific in the United States, Australia, Brazil, Cambodia, China, Japan, Laos, Malaysia, New Zealand, the Philippines, South Korea, and Vietnam. Outbreaks typically happen when vaccination rates drop.
“The cost of contact tracing and stopping the spread can be very high, but it has to be done,” said Chow Chun-bong, an honorary professor at the Department of Pediatrics and Adolescent Medicine at the University of Hong Kong.
The main reason for the outbreak in many countries－like the Philippines, the US, and Samoa－is decreasing vaccination rates from anti-vaccine campaigns. In places where the vaccination rate is high－like Japan and Australia－small outbreaks can occur at airports and hospitals due to the importation and accumulation of secondary vaccine failure cases, usually in young adults.
Economic development can also suffer due to decreasing vaccination rates. Providing vaccinations is cheaper than dealing with outbreaks, which can lead to higher healthcare costs.
The World Bank described vaccines as “one of the most cost-effective investments in health and economic development”.
Widespread vaccinations have helped drastically lower the incidence of measles around the world since 1963, when a vaccine was introduced. Before that, measles outbreaks took place every two or three years and killed more than 2.5 million people every year on average. The number had dropped to about 110,000 before the recent surge.
However, countries like the UK that were considered “measles-free” just a few years ago are no longer so after the disease spiked up again in 2017, according to the WHO.
Yuen Kwok-yung, an infectious diseases expert from the University of Hong Kong, pointed out two reasons why the incidence of measles is back on the rise.
“Often it is because the childhood vaccination uptake rate is lower because parents have a false belief that vaccinations can be harmful,” Yuen said.
He said that in other cases, the neutralizing antibody level after receiving a vaccination decreases to a low level in adulthood. The recurring incidence is likely the result of an expansion in anti-vaccine movements around the world.
“The anti-vaccine movement has been gaining ground in recent years, and this is the reason the WHO made it one of the top 10 threats these years,” said Xu from Zhejiang University.
Hong Kong’s Department of Health said the incidence of measles in some Asia-Pacific countries and regions has been high since 2018. In the Philippines, for example, some 44,000 cases were reported this year, and the outbreak is ongoing. Hong Kong also experienced an uptick in measles this year, with 91 cases reported by Dec 12.