“…Likewise, the human immune system is often unexpected in its responses to various stimuli and difficult to model. 8 So, only about 7% of vaccine candidates can complete preclinical development, and only about 15% to 20% of candidates can go through clinical trials and receive market approval. 9 Considering the feature of vaccine development, governments had to invest in a diverse portfolio to maximise the chances of finding a successful and effective vaccine as quickly as possible.…”