Table 1. Description of some related work indicating pros and cons of existing approaches.

Ref	Data set	Method	pros	cons
Pereira et al. (2020)	RYDLS-20	Early and late fusion techniques	Multi-class classification+ hierarchical classification	Data sparsity and feature optimization missing
Apostolopoulos, Aznaouridis & Tzani (2020)	Custom	Mobile Net	Considered feature extraction approaches	6-class problem
Oh, Park & Ye (2020)	Custom	Patch-based CNN	Employed Potential imaging biomarkers for validation	5-class problem
Apostolopoulos & Mpesiana (2020)	Custom	Transfer learning based CNN	Considered bacterial and viral pneumonia target class	5-class problem
Yoo et al. (2020)	Custom	Decision-tree classifier	Merging deep learning in tree classifier	3-class problem