Curbing COVID-19, but at What Cost?
Global responses to the pandemic may lead to a relapse in polio.
By Emily Harari, Sophie Timmermann and Diyala Shihadih
Elena Conis contributed research
For decades, the world has worked to eradicate polio, and we have never been closer. On August 24, the entire Africa-region was certified wild-polio-free. Now, only two endemic countries remain: Afghanistan and Pakistan.
But global responses to the novel coronavirus threaten to reverse these culminating achievements in unprecedented disease control. The global campaign to keep polio at bay was largely suspended in spring to stem the spread of the coronavirus.
Failure to achieve polio eradication could result in a global resurgence “with as many as 200,000 new cases occurring every single year, within ten years, all over the world,” said Oliver Rosenbauer, polio eradication spokesperson for the World Health Organization (WHO).
Now, more than ever, countries need to be vigilant and track the children that were missed during halted campaigns to prevent new polio spikes. But this requires costly surveillance. The U.S.’ announcement to leave the WHO and pull its funding in the midst of a global pandemic could not have come at a worse time.
Polio was once feared globally, a disease which paralysed children for life.When the global initiative to eradicate polio was launched in 1988, the widely accessible vaccines encouraged public health officials that their goal was feasible. Moreover, smallpox eradication in 1980 restored faith in the global arena — eight years later and polio was the second target for infectious disease eradication.
Thankfully, unlike the coronavirus, polio doesn’t have an animal host. The plan for eradication seems straightforward: Eliminate polio in people, and you eliminate it from the Earth. But not all vaccinations are created equal. An injected polio vaccine was first introduced in the fifties and, shortly after, a more easily administered ‘live’ oral polio vaccine came along. With the benefits of the oral vaccine also came the rare risk of re-circulating a more virulent ‘vaccine-derived’ poliovirus.
Today, Americans exclusively receive the injected vaccine because it doesn’t carry the same risk as the oral one. The U.S. was able to ditch the oral vaccine after 1999, once it hit the 80 percent minimum vaccination rate necessary to prevent a polio epidemic. Yet, in countries with low vaccination coverage the oral vaccine is still used for its ease of administration and limited temperature sensitivity.
When the global initiative to eradicate polio began, the disease existed in more than 120 countries. Today, polio is confined to Afghanistan and Pakistan, where lack of infrastructure and mistrust of vaccines pose obstacles only exacerbated by the coronavirus pandemic.
Polio’s worst feature is not just the paralysis it causes; it is highly infectious. The virus can survive in human waste for weeks. Every case leads to five to seven other infections. The WHO also recommends giving the vaccine doses quickly, starting with two doses in the first two months of life. When any of those doses are missed, it creates “immunity gaps” that can lead to new polio cases, says UNICEF Afghanistan spokesperson Kamal Sha.
According to UNICEF, 50 million children have missed their vaccines in the past months, leaving especially those under 5 vulnerable to the disease. From the WHO’s most recent June 2020 International Health Regulations, in Afghanistan and Pakistan, novel polio strains are emerging and “the risk of international spread is at the highest point since 2014 when the PHEIC [Public Health Emergency of International Concern] was declared.”
Pakistan and Afghanistan responded by resuming their polio vaccination campaigns in the end of July, but social distancing measures still limit outreach. Both countries will need to catch up on these missed doses to avoid immunity gaps that could lead to new outbreaks. And they need international support to do so.
Suspended campaigns come at a cost. In 2003, the Nigerian government halted vaccination campaigns in three northern states for just one year, and suffered the consequences for three years after. Polio spread from Nigeria to 20 previously polio-free countries, reaching as far as Indonesia. More than 1500 children were paralyzed.
But Africa’s wild-polio free certification is proof that interrupted campaigns can recover. In 1996, polio paralyzed more than 75,000 children in Africa, affecting every country on the continent. By 2016, the disease was confined to Nigeria and today the region is polio-free.
A polio outbreak today would be different — government lockdowns, reduced global air travel, and tightened border controls — but the 2003 resurgence “gives some indication” of what could follow the recent vaccination suspensions, according to Mr. Rosenbauer.
That is because polio campaign workers don’t just vaccinate. They also test human waste and water sources for traces of poliovirus, because its presence is an early indicator of infection spread. But these efforts have also been curtailed, as workers are reassigned to coronavirus control, or as their travel is restricted. And the consequences are beginning to show.
By the end of September, the number of vaccine-derived polio cases almost experienced a threefold increase compared to the same period last year. In July, the U.S. formally moved to withdraw its funding to the WHO, in spite of warnings from global public health officials.
Granted, polio vaccine coverage in the U.S. is high, making a polio outbreak in the U.S. very unlikely. But “it takes only one traveler with polio to bring the disease into the United States,” according to the U.S. Center for Disease Control. U.S. measles outbreaks in 2019 and 2014, both linked to domestic travelers contracting the disease abroad demonstrated that — short of eradication — resurgence of long-controlled epidemic diseases is always a possibility.
