Countries Forge Ahead with Complex Polio Vaccine Transition
June 6, 2015
Despite concerns about costs, vaccine supply, and tight deadlines, country health leaders have reaffirmed support for highly ambitious polio vaccine plans considered necessary to achieve full global polio eradication. Delegates to the 68th World Health Assembly (WHA) in Geneva approved a resolution last month that urges member states to prepare for a worldwide transfer in 2016 from widely used trivalent oral polio vaccine (OPV) to a bivalent version that withdraws the type 2 component of the vaccine. The move would eliminate from immunization programs the strain of the vaccine most associated with vaccine-derived polio cases. It will be important to carefully watch the preparations for and implementation of these plans over the course of 2015 and into 2016.
The Global Polio Eradication Initiative’s strategic plan for 2013-2018, endorsed by the WHA two years ago, calls for a worldwide vaccine shift now planned for a two-week window in April 2016. The switch would be the first step in eventual withdrawal of all OPV, a live, weakened virus vaccine that in rare instances causes the disease in those vaccinated and sometimes in those around them (55 cases globally last year). Naturally occurring type 2 polio was eliminated worldwide in 1999 and more than 90 percent of all vaccine-derived polio cases are caused by the type 2 component in the vaccine. In approving the resolution last week, countries recommitted to:
- Developing national plans by the end of September 2015 for the withdrawal of the type 2 component of OPV and replacement with bivalent OPV;
- Expediting registration of bivalent OPV for use in routine immunization programs;
- Implementing national policy for the destruction of residual trivalent OPV stocks.
In another major action connected to the shift, countries also are being asked to introduce at least one dose of the injectable inactivated poliovirus vaccine (IPV) into their national immunization systems, “optimally” before withdrawing type 2 of the OPV. Since it contains a killed virus, IPV protects against all three polio types without the risk of causing the disease. As of May 1, 2015, 87 countries have introduced IPV into their immunization systems. Another 103 have made a formal commitment to begin using the vaccine this year, while an additional four countries have said they intend to introduce it this year. Vaccinating as many children as possible with IPV before the switch is necessary to maintain immunity against type 2 poliovirus as it is withdrawn from OPV. Many countries will continue using both IPV and bivalent OPV for the time being since OPV is less expensive, easier to administer, and confers broader-based immunity within communities.
In approving the resolution, delegates turned down an amendment offered by Indonesia that would have loosened the deadlines included in the strategy to allow countries to introduce IPV and make the OPV switch at their own pace. Indonesia produces its own vaccine stores and was concerned about being able to supply all the IPV it needed in the proposed GPEI time frame. But immunization experts agree that the switch has to be made by all countries simultaneously to ensure that type 2 OPV is withdrawn worldwide and therefore unable to cause additional paralysis. Countries speaking at the WHA session noted the current momentum toward polio eradication and urged maintaining timelines outlined in the plan. WHO officials said they would work with Indonesia to address its concerns.
But the plan asks a lot of many countries. Jamaica, for example, noted that its costs for IPV are $2.80 a dose versus 13 cents for OPV, a concern echoed particularly by others in the Caribbean region. Gavi, the Vaccine Alliance, is providing aid to 73 eligible countries to help them with vaccine purchases and related needs, but that still leaves many programs to deal with the costly increase themselves. Countries also expressed concern about ensuring an adequate supply of IPV.
Michel Zaffran, who coordinates WHO’s Expanded Program on Immunization, acknowledged that many countries are “challenged by the timeline” and that the supply of IPV is tight. But, he added, there is strong support for the strategy and countries are moving forward. WHO and other GPEI partners are working with manufacturers to increase available vaccine and find ways to reduce the price. Some countries, for example, have approved IPV formulations that can be used for up to 28 days after they are opened. Previous guidelines called for disposing of multi-dose vials at the end of each day, creating significant wastage.
To help ensure it can effectively aid countries in the vaccine switch, the GPEI is conducting trial runs in several countries, including India and Indonesia. These exercises will help develop protocols that can be employed next year. The switch will involve making sure all trivalent vaccine is destroyed or safely stored and that bivalent versions are funneled into vaccine supply chains in adequate quantities.
Despite widespread support and preparations, there still is significant concern over whether countries will be adequately prepared. WHO’s Strategic Advisory Group of Experts (SAGE) on Immunization, which makes recommendation about global vaccine policies, will decide in October 2015 if the switch should go ahead with the April target date, the low season of poliovirus in countries with persistent poliovirus transmission. The panel will base its assessment on several factors including whether there are any active vaccine-derived polio cases and the status of the vaccine supply. If SAGE decides the time is not yet right, the switch could be postponed for as long as another year, risking further cases of vaccine-associated disease.
While both IPV introduction and phased OPV withdrawal are required to achieve final polio eradication, these planned steps are ambitious and daunting. Many countries still have weak routine immunization systems and making IPV widely available will be a challenge, as will ensuring proper logistics are in place to make the worldwide OPV switch. The U.S. government has been a key supporter of polio eradication largely through the Centers for Disease Control and Prevention (CDC) and the U.S. Agency for International Development (USAID). USAID is aiding in the introduction of IPV by supporting social mobilization and communications operations and linking polio eradication activities with routine immunization programs. CDC is involved in GPEI governance as a core partner of the initiative and is conducting critical implementation research. It also is training consultants who will aid countries in the OPV switch. In addition, CDC is examining possible scenarios for what could happen if not all countries make the switch and is helping monitoring country readiness. As outlined in this commentary, contributions from both CDC and USAID will be pivotal to ensuring the success of this next phase of polio eradication
The next year is critical for polio eradication and the stakes are high. Continued vigilance and solid support are required to ensure adequate resources and technical assistance are available to countries as they make the necessary but challenging vaccine adjustments. The U.S. and the global community should stay actively engaged to ensure this complex global endeavor remains on track and is successfully implemented.