The global polio eradication effort is moving one step closer to success with the upcoming rollout of a new vaccine, the novel oral polio vaccine type 2 (nOPV2), slated to occur within the next month. Under the vaccine’s emergency approval from the World Health Organization (WHO), The Task Force’s Polio Eradication Surge Capacity Team is working with priority countries to prepare their health systems for the roll-out of nOPV2, which improves on the current oral polio vaccine because trials have shown that it will reduce cases of vaccine-derived polio.
Task Force Polio Surge Team Senior Epidemiologist Victor Eboh, MD, spoke with us about what this new vaccine means for polio eradication and what it takes to prepare a health system for a new vaccine rollout. Eboh is working in Sierra Leone with the Ministry of Health and Sanitation to coordinate vaccine-derived polio outbreak response and provide technical support and guidance for the nOPV2 rollout.
First, a brief bit of background on the virus and the current oral vaccine, to provide context for the discussion that follows: Wild poliovirus is the original form of the virus and has three immunologically distinct types that can cause paralysis and death; types 2 and 3 have been eradicated from the world, while type 1 wild poliovirus is the one Africa eliminated in 2020 and which is only circulating in Afghanistan and Pakistan. However, vaccine-derived polio outbreaks still occur in many African and Asian countries with more than 575 active cases in Africa as of end January 2021. Vaccine-derived polio is caused when the weakened live virus in the current oral vaccine (mOPV2) reverts back to a paralytic form. In areas where vaccination rates are high enough – around 80-85% of eligible children – this doesn’t cause a problem. But in places where vaccination coverage is low and there are inadequate sewage systems, this excreted vaccine-virus can reintroduce poliovirus into the community and, in very rare instances, lead to an outbreak of paralytic polio.
Q: There are two main different types of polio: wild poliovirus and vaccine-derived poliovirus. This new vaccine will prevent cases of wild polio but also reduce vaccine-derived polio, so what does that mean for polio eradication?
The novel oral polio vaccine type 2 is the latest tool in the polio eradication effort. Outbreaks of vaccine-derived polio have been a real challenge for many countries and circulating cases have significantly increased during the coronavirus pandemic. Clinical trials have shown that nOPV2 provides comparable protection against type 2 poliovirus while being significantly more genetically stable and therefore less likely to revert to a form that can cause paralysis in under-immunized communities.
The original plan was to roll out the vaccine globally between August and September 2020, but because of the pandemic and all of the logistics required, it has been postponed until now. The roll out plan has identified first-tier and second-tier countries, prioritizing those with the greatest need and the ability to successfully introduce the new vaccine. Currently, I am supporting first-tier countries like Sierra Leone and Liberia to help them meet all of the required guidelines. Other epidemiologists on our team are supporting countries like South Sudan and Ethiopia. In these countries, children 5 years old and younger are the target population for the new vaccine because they are the most at risk due to their exposure to excreted virus in their environments and suboptimal immunization coverage.
Q: With the COVID-19 vaccine also rolling out globally, the process of introducing a new vaccine is top of mind for many people. Walk us through what it takes to roll out a new vaccine in a country.
It is obviously different for every vaccine and target population, but for nOPV2, there are quite a number of stringent requirements and readiness assessments indicators that have to be met from making sure that the logistics are in place to ensuring that the new vaccine is safely introduced into communities.
For polio eradication, we conduct surveillance in a community to identify all possible causes of paralysis and then we take samples to see if that instance of paralysis is caused by poliovirus. So before the vaccine is introduced, we have to ensure that key surveillance performance indicators are actually up to standard and there are no gaps in the country’s surveillance system. Environmental surveillance is also conducted to check for excretion of the virus in the sewage and water systems so we have to ensure that surveillance is working accurately. So, for example, here in Sierra Leone, we are having to start up an environmental surveillance system because they didn’t previously have that infrastructure in their health system. The Task Force, CDC, UNICEF, WHO, and the Sierra Leone Ministry of Health and Sanitation have been working together to get that up and running so that the country can continue to track evidence of the virus in the sewage systems once the new vaccine is introduced.
Other logistics that need to be in place before roll out are things like training so that health workers know how to administer the vaccine, ensuring that the cold chain for storage and transportation of the vaccine is ready, and communicating to the public about why this new vaccine is safer and more effective so that communities are receptive to getting the vaccine. Then you have administrative requirements that need to be ready along with vaccine safety monitoring protocols which are established by a country’s national drug regulation authority, similar to the Federal Drug Administration in the United States. In total there are 25 indicators that have to be 100% met before the vaccine can be rolled out in a country.
Q: Do you expect any vaccine hesitancy from communities with this new vaccine?
Similar to distributing the COVID-19 vaccine, there is also a communications effort that needs to happen to help people understand the need and to address their concerns about its effectiveness and safety. With headlines covering the COVID-19 vaccine regularly, vaccine hesitancy and concerns have seemed to increase in many of the communities that we are working with, so we have to work even harder to communicate about the safety, importance, and development of the new polio vaccine. That means involving community leaders in the places where vaccination campaigns will take place to increase confidence in this well-researched vaccine. One of the things I’ve learned when it comes to communicating especially about a new vaccine or medication, there will definitely be some resistance, but for parents and caregivers it is very important to listen to their fears to understand them and to address them.
Q: Walk us through a vaccination campaign.
Routine vaccination campaigns for polio have a full dosing schedule that a child follows from birth. When there is an outbreak, we do supplementary vaccination campaigns in addition to the routine vaccination campaigns. The outbreak response activities are often door-to-door campaigns because it is a public health emergency so we don’t wait for families to bring in their children for a regular visit to a doctor. Community health workers go to the families to ensure that they have received the appropriate doses and therefore protected against the outbreak. Outbreak response vaccination campaigns are much more expanded than routine campaigns so trained vaccine carriers try to reach every single child, even beyond where the initial outbreak is happening. In remote places, this means riding donkeys, biking miles, paddling canoes up rivers, getting to every household no matter how difficult the transportation is. The goal is to reach every last child.
Q: How has COVID-19 complicated this effort? Are there new measures that will have to be taken into consideration?
Not only has COVID-19 delayed the roll out and increased cases because vaccination campaigns were paused back in 2020 due to lockdowns, but another immediate impact is that much of the workforce that is working on the nOPV2 roll out are the same people who are actively involved in COVID-19 response, so these countries are working to juggle competing priorities. Human resources are low, and we’re racing against the clock on both COVID-19 and polio in order to reach as many people as quickly as possible to keep them safe from both of these diseases. The pure increase in cases has been the most detrimental impact though. COVID-19 has diverted many resources from polio eradication efforts leaving many communities vulnerable to polio outbreaks.