Pakistan's fight against polio has reached a promising milestone, with environmental virus detections plummeting by more than 70 percent in just one year. Yet beneath this success lies a persistent threat that no vaccination campaign can fully control: the unchecked movement of people across the Afghan border. Main Developments Environmental samples collected across Pakistan during June 2026 showed a positivity rate of just 13.1 percent, down sharply from 48.1 percent during the same period last year. Of 127 samples tested, only 10 were positive for poliovirus, according to data from the National Emergency Operations Centre (NEOC). The decline in positive environmental samples from January to June was even steeper: 100 this year versus 369 in the same span of 2025. Punjab reported no positive samples at all in June, while Sindh had just one, Khyber Pakhtunkhwa four, and Balochistan five. Read also: Why Pakistan's Warning to Houthis Signals a Shift in Red Sea Strategy Background Environmental surveillance has long been a critical measure of polio eradication progress, as the virus found in sewage indicates ongoing circulation and immunization gaps. Pakistan has reported three wild poliovirus cases so far in 2026, underscoring that transmission has not been fully interrupted. Prime Minister's Focal Person Ayesha Raza Farooq attributed the improvement to a new strategy that included external audits, better team selection, enhanced training, and law enforcement support. In Karachi, an external audit led to the retraining of vaccination teams, with cooperation from the Sindh chief secretary helping reduce positive samples to just one in June. Challenges remain in southern Khyber Pakhtunkhwa and Karachi, where routine immunization coverage is still unsatisfactory. Access issues in Khyber Pakhtunkhwa have required involvement of both law enforcement and local communities, Farooq said. Why It Matters The sharp drop in environmental positivity suggests that vaccination campaigns are reaching more children and that surveillance is improving. However, a polio expert speaking anonymously warned that cross-border movement from Afghanistan remains a major concern, with virus strains linked to Kandahar and Nangarhar detected in Quetta and Peshawar samples. Until border controls are strengthened or Afghanistan's own polio situation improves, imported cases could reverse Pakistan's hard-won gains. The NEOC stressed that sustained vigilance is essential to interrupt virus transmission completely. What's Next Pakistan's NEOC plans to intensify surveillance and vaccination efforts in high-risk areas, particularly in southern Khyber Pakhtunkhwa and Karachi. Community leaders, religious scholars, and healthcare professionals are being urged to support polio workers and encourage vaccination. Prime Minister Shehbaz Sharif is personally monitoring the situation, Farooq said, signaling high-level commitment. Whether the downward trend can be maintained will depend on closing immunization gaps in dense urban areas and addressing the cross-border challenge that remains beyond Pakistan's sole control.