A Pakistani health worker gives polio vaccine to a child in Lahore, Pakistan, in April. (K.M. Chaudary/Associated Press)

PAKISTAN NOW stands as the main barrier to the global elimination of wild poliovirus. In two other countries where it is endemic, things are going well: There hasn’t been a case in Nigeria in nine months, and there has been only one in Afghanistan so far this year. Outbreaks last year in Syria, Iraq and other parts of Africa have been contained. Consider the progress: In 1988, there were more than 125 countries where polio was endemic. But now, all eyes are on Pakistan as the high season approaches for transmission of the virus. Plans are in place for the fight, methods are known, good intentions declared. Now a nation often weakened by its own internal chaos must deliver.

The poliovirus is highly contagious, largely strikes children under 5 years old and can cause permanent paralysis. The oral vaccine is effective if it can be given to enough children to prevent and interrupt transmission.

Last year, Pakistan recorded 306 cases, which was the highest in 15 years and 85 percent of all those in the entire world. A review of the program in October declared, “Pakistan’s polio programme is a disaster.” The review found inadequate political backing, poor public health programs and little engagement at the local level. “Something big has to change in Pakistan,” the review concluded. Then, Pakistan began this year with a terrible surge of attacks on vaccination teams in what looked like a new campaign by Taliban militants. Violence is a major disruption to the vaccination effort, tearing a hole in the prevention net and allowing the virus to spread.

For two years, children in North and South Waziristan could not be vaccinated because local leaders suspended the campaigns. Then a military operation in the North Waziristan and Khyber tribal areas in the last six months of 2014 displaced nearly a million people. The movement created risks of the virus spreading, but it also opened up a window of opportunity to vaccinate children who had been inaccessible. Outbreaks occur even in more stable areas in Pakistan, where there are clusters of unvaccinated children. Fortunately, research shows that parents have a high degree of acceptance of the need for oral polio vaccines, although suspicion and distrust still linger in some places.

Pakistan is rallying. There have been only 22 cases so far this year, compared with almost 60 at this time last year. Violence has abated, at least in the past month. Emergency operations centers, an important innovation to help monitor the virus, have been set up. Experts also applaud another recent tactic, the recruitment of female volunteers to work on vaccination in their own communities with approval from local religious and tribal leaders. This approach seems to be making headway in previously inaccessible areas. Pakistan’s political leadership also has vowed a renewed campaign.

In the end, the only metric that really counts with polio is getting to zero. The world has never been closer. Pakistan could do much to push this disease into the history books.