Barack Obama's inauguration as US President has largely been seen around the world as positive, but what will it mean for global health? Two major breaks with previous policy have gone almost unnoticed.

The first was the forced resignation (1) of Ambassador Mark Dybul, the controversial head of Bush's $48 billion President's Emergency Plan for AIDS Relief (PEPFAR) (2) the day after Obama's inauguration. The second came when Obama overturned the Mexico City Protocol, (3 ) which prevents US aid to overseas organisations providing or discussing abortion-related services.

PEPFAR has always courted controversy: (4) for pumping billions into programmes for just one disease, for promoting abstinence-only prevention, for not funding family planning services, for being bilateral when it is argued funds are better funnelled through the multilateral Global Fund for AIDS, TB & Malaria, ( 5) and for being seen as driven by a conservative Christian agenda. (6) But PEPFAR has been far more effective than credited: it got 2.1 million people in 15 countries onto antiretroviral therapy, distributed 2.2 billion condoms (countering the charge prevention's focus was abstinence-only), and gave access to anti-HIV therapy to prevent mother-to-child infection to 1.2 million women. Only 7.4% of its budget went to abstinence-only programmes. (7)

Obama will honour the December 2008 PEPFAR act to pump nearly $50 billion extra into HIV prevention, care and treatment over five years. More of that money will probably now go to family planning services that will undoubtedly save lives. (8) That some of those services will promote and provide abortion causes concern.

The world will watch Obama with interest. If he can live up to and exceed Bush's legacy in the developing world, it will be good news for many. But uncertainties remain about the other forces that may move his hand less helpfully. Let us uphold him and all leaders (9) in prayer.