Complex sentence: He held firm in his pledge until August 2003 when a national congress of TAC activists voted to urge him to begin taking his medicines; he finally announced that he would start shortly before the government announced that it would make antiretrovirals available in the public sector.
Split into simpler sentences: He held firm in his pledge until August 2003 when a national congress of TAC activists voted to urge him to begin antiretroviral treatment. He finally announced that he would start treatment shortly before the government announced that it would make antiretrovirals available in the public sector.