A nurse prepares a polio  vaccination for a baby in the Otash refugee camp in South Darfur. United Nations and Sudanese agencies will carry out the campaign this week and again in November. Sudan had been polio-free since two thousand and five. The new case of wild polio virus was _ last month in South Darfur. Health officials also announced last month that Nigeria has had almost seventy new cases of polio since two thousand and five. Those cases, however, were caused by the polio vaccine itself. There are two kinds of polio vaccine . The one given by injection contains killed virus, which cannot cause polio. The one given by mouth contains live but weakened virus. In very rare cases the virus can change and cause polio. The way to stop the spread now is more vaccinations. But officials worry that people in northern Nigeria may, once again, fear the vaccine. In recent years, local leaders spread stories that Western nations had poisoned the vaccine with the virus that causes AIDS. The United States Food and Drug Administration had told parents not to give them to children under age two unless a doctor says to use them. The F.D.A. gave the advice as it announced a meeting of experts to discuss cold medicines for children. That advisory committee met last week -- and voted that these drugs should not be given to children under the age of six. Members said there is not enough evidence to show that these drugs work in children. They called for more research. The committee also said that liquid medicines should all use the same measurement terms. This could reduce the risk of parents giving their children too much. _  The drug industry says its products are safe and effective for children. But it says parents need to be better educated about how to use them. A week before the meeting, the industry decided to end sales of cold products for children under two. We can infer from the passage that  _  .
the United States Food and Drug Administration had told parents not to give them to     children under age two there is enough evidence to show that these drugs work in children a week before the meeting, the industry decided to end sales of cold products for children under six It should be cautious for children's taking cold medicine