Complex sentence: The vaccine was intended to be ready for use after clinical trials in November or December, however, because swine influenza still was considered to be a mild disease, the influenza vaccine could not be used without approval by the European Medicines Agency (EMEA).
Split into simpler sentences: The vaccine was intended to be ready for use after clinical trials in November or December. Because swine influenza still was considered to be a mild disease, the pandemic vaccine could not be used before approval by the European Medicines Agency (EMEA).