In DepthGlobal Health

Pandemic brings mass vaccinations to a halt

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Science  10 Apr 2020:
Vol. 368, Issue 6487, pp. 116-117
DOI: 10.1126/science.368.6487.116

Science's COVID-19 coverage is supported by the Pulitzer Center.

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Door-to-door campaigns against polio, such as this one in Kenya in 2018, could help spread COVID-19.


“A devil's choice.” That's how Seth Berkley, head of GAVI, the Vaccine Alliance, describes the dilemma facing global health organizations in the past few weeks. They could either continue to support mass vaccination campaigns in poor countries but risk that they would inadvertently help spread COVID-19—or recommend their suspension, inevitably triggering an upsurge of many other infectious diseases.

In the end, they chose the latter, and mass vaccination campaigns against a host of diseases are now grinding to a halt in many countries. For many children, these campaigns are the only chance to get vaccines. Some 13.5 million have already missed out on vaccinations for polio, measles, human papillomavirus, yellow fever, cholera, and meningitis since the suspensions began, Berkley says. “I tell you those numbers will be much larger than what we see today.” The fallout may last long after the pandemic subsides. And in the case of polio, the pause imperils the success of a 3-decade eradication campaign that was already in trouble.

The suspensions began on 24 March, when leaders of the Global Polio Eradication Initiative (GPEI) called on countries to postpone all polio vaccination campaigns until the second half of the year. The huge campaigns—door-to-door efforts that reach 400 million to 450 million annually—are the mainstay of the eradication program. Yet, “We had no choice,” says Michel Zaffran of the World Health Organization (WHO), who heads GPEI. The vaccination drives would put both communities and frontline health workers at risk of infection with the coronavirus, he says. But he concedes more children will be paralyzed in countries where polio is still circulating, and the virus will likely spread to countries that are now polio-free.

The polio eradication effort is already reeling from setbacks in Afghanistan and Pakistan, where the wild virus is surging, and in Africa, where outbreaks caused by the live polio vaccine itself are spiraling out of control (Science, 3 January, p. 14). “Everyone was uncomfortable” with suspending campaigns, Zaffran says. But in the end, the only real tension among GPEI leaders was whether to call for a firm halt not only to preventive campaigns, but also to the targeted campaigns in response to the vaccine-derived outbreaks in Africa. Ultimately, “The guidance came from a very high level to pause everything,” says Rebecca Martin of the U.S. Centers for Disease Control and Prevention (CDC). (GPEI's Polio Oversight Board is composed of the heads of all the partner agencies, including WHO Director-General Tedros Adhanom Ghebreyesus.) The program will reassess the decision every 2 weeks.

On 26 March, WHO's Strategic Advisory Group of Experts on Immunization (SAGE) issued a broader call, recommending that countries stop mass vaccination campaigns against all vaccine-preventable diseases. “Any mass campaigns would go against the idea of social distancing,” says Alejandro Cravioto of the National Autonomous University of Mexico's Faculty of Medicine, who chairs SAGE.

Twenty-three countries have already suspended their measles campaigns, and as a result, 78 million children will miss out on the vaccine, says Robb Linkins, a measles expert in CDC's Global Immunization Division. Sixteen other countries are still deciding. Linkins foresees “tragic” consequences. In poor countries, the virus can kill 3% to 6% of those it infects, WHO says, with malnourished children especially at risk. Measles infected an estimated 10 million and killed 140,000 in 2018, the last year for which numbers are complete. And because measles is incredibly contagious, case numbers could quickly surge following the suspensions.

Unlike the polio initiative, SAGE stopped short of recommending that countries halt campaigns to quell ongoing outbreaks, but it said they should carefully weigh the risk of an immediate response against that of a delayed one. For now, measles campaigns are continuing in the Democratic Republic of the Congo, where the world's biggest outbreak has so far killed an estimated 6500 children—far more than the recent Ebola outbreak in that country—and sickened more than 340,000.

WHO, GAVI, and other health organizations stress that routine immunization of individual children at clinics must continue as much as possible during the pandemic. But health systems in many countries were already stretched thin, and protective gear is often lacking. Berkley fears severe disruptions of routine immunization if health workers are diverted to COVID-19 or become sick or die, or if parents are afraid to bring their children to a clinic. Vaccines may run out as well. Some countries are already experiencing shortages as flights are grounded and borders close, Berkley says.

Other essential health services will also be disrupted, says Augustin Augier, executive director of the Alliance for International Medical Action. Every year, ALIMA trains about 500,000 African mothers to diagnose acute, potentially fatal malnutrition in their children; those programs have been suspended. The knock-on consequences of the pandemic “will be much stronger and more lethal for the world's most vulnerable populations,” Augier says.

Across all these programs, the goal is to come back hard and fast to regain lost ground once the pandemic is over. In the meantime, WHO says, countries should continue surveillance for vaccine-preventable diseases to figure out where pathogens are circulating and which children are most at risk. But that, too, is a challenge amid the fear and disruption from COVID-19.

Berkley sees some hope in the experience in West Africa after the 2014–15 Ebola outbreak. “There was an unprecedented flow of finance and good will,” he says. “We did campaigns once Ebola was over and strengthened routine immunization. We not only recovered coverage levels, but exceeded them.” But that epidemic was largely confined to three countries with a combined population of fewer than 25 million people. This time, the entire world is affected.

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