Islamabad, March 29 : Pakistan on Monday launched a new door-to-door campaign to vaccinate millions of children against polio despite the risks posed by increasing coronavirus infections, an official said. The five-day campaign will target over 40 million children under the age of five, reports dpa news agency. Around 285,000 frontline workers will span out across Pakistan's 156 districts to administer the oral drops while following Covid-19 safety protocols. "Covid-19 continues to challenge us but we are committed to ensure continuity of the essential public health services during these difficult times," the Special Assistant to the Prime Minister on Health, Faisal Sultan, said in a statement. Pakistan and Afghanistan are among only a few countries in the world where polio is still endemic. The country came very close to eliminating polio, but recorded 147 cases, a five-year high, in 2019, amid vaccine boycotts and attacks on health workers. Pakistan started a polio programme in 1994, but the work of the health workers was repeatedly hampered by violent incidents by extremists. The UN-funded drive also faces opposition from religious conservatives, who believe the vaccine, administered in multiple rounds, is intended to make Muslim children sterile. The second polio vaccination drive of the year started at a time when country is battling to bring down steadily rising daily infections of coronavirus, over 4,000 per day, amid a third wave of the pandemic. On Monday, Pakistan put virus hotspots in over two dozen cities with higher infection rate under lockdown and started the process of vaccinating people aged 50 and above. The Covid-19 vaccination campaign had started last month but has received a lukewarm response. /IANS