Rearrange the following five sentences (A), (B), (C), (D) and (E) in the proper sequence to form a meaningful paragraph, then answer the questions given below them.

A. Large-scale trials are required to ascertain if the vaccine actually protects against the pathogen.

B. It is heartening that the Pune-based Serum Institute of India has received the country’s top drug regulator’s approval to conduct late-stage human trials for the Oxford-AstraZeneca COVID-19 vaccine candidate. 

C. Its mild side effects augur a safe vaccine. 

D. The vaccine has shown encouraging results in early trials.

E. But scientists have rightly advised the tempering of hope with caution.