[Grammar] 'Than was' or 'than it was'?

[Cristina.W]

'The results indicate that the new drug is safer than was previeuosly assumed.'
Doesn't 'was' need a subject?

 

[MikeNewYork]

No. It is fine if you correct the spelling of "previously".

 

[emsr2d2]

You can omit "was" and it will still be an acceptable sentence.

The results indicate that the drug is safer than previously assumed.

 

[Raymott]

'The results indicate that the new drug is safer than was previeuosly assumed.'
Doesn't 'was' need a subject?

It does have a subject, though it's implicit.
'The results indicate that the new drug is safer than the drug was previously assumed to be.'
If you use 'it', you still need to add 'to be' on the end. It's a very ellipted and elliptible sentence.