While in Africa, the pontiff is expected to talk to young people about the Aids epidemic and explain to them why the Catholic Church recommends sexual abstinence as the best way to prevent the spread of the disease.
The Pope is entitled to his opinion on the ethics of condom use however I do not believe he is entitled to make inaccurate statements about the efficacy of abstinence programs versus condom use. Since I don't believe the Pope is likely to read this I'm not going to go to go into too much detail but you may remember this study from a couple of years back:
Sex abstinence programmes do not stop risky sexual behaviour or help in the prevention of unwanted pregnancy, a research team has concluded. The Oxford University team reviewed 13 US trials involving over 15,000 people aged 10 to 21. They found abstinence programmes had no negative or positive impact on the rates of sex infections or unprotected sex, the British Medical Journal said.