MEDICS will vaccinate about 2.9 million young children against polio in Malawi, the United Nations said, after a three-year-old girl fell sick in the capital with Africa's first case of wild poliovirus in more than five years. The southern African country declared a polio outbreak two weeks ago after tests confirmed the infection and showed the strain was linked to one circulating in Pakistan, where it is still endemic. "The resurgence of the wild poliovirus in Malawi ... is cause for serious concern," Rudolf Schwenk, the head of the U.N. children's agency UNICEF in Malawi, said in a statement. "Vaccination…