**5. A future for phages**

The research on phages and their possible antiviral properties are fundamental and should be approved by meticulous *in-vitro* and *in-vivo* studies. If lab research shows some promising results, then it could be possible to have clinical research and randomized stage from one to three human trials to prove their therapeutic utility. Phage therapy may likewise hold promise as a treatment for SARS-CoV-2 [11].

The bacterial growth rate might potentially be diminished by the aerosol use of bacteriophages that prey on the original species of bacteria responsible to cause respiratory failures [34]. This can occur in a self-administrative manner, similar to prey–predator regulation in ecosystem. The remarkable development of the bacteriophage population should allow for a fast clearance, particularly in situations where the bacterial population has already grown significantly [35].

In a study conducted by *Prazak et al.* in 2020, they found the evidences that pneumonia can be treated by nebulized bacteriophages. Target bacteria that commonly cause respiratory problems and selection of bacteriophages can be quickly identified through screening method and by group of experts. Prophylactically administered bacteriophages decreased lung bacterial burdens and improved endurance of antibiotic resistant *S. aureus* infected animals with regards to ventilator-associated pneumonia [36]. It should be ensured to have the right selection of bacteriophages that target both the optimal bacteria and should be most effective against bacterial population growth. The bacteriophages should not interfere with the patient's innate or adaptive immunity. It is also very necessary to rule out that patient does not have antibodies toward bacteriophages used, nor develops any antibodies toward bacteriophages to clear off the bacteriophage earlier than to SARS-CoV-2. If required, quantitative microbiome sequencing can be used potentially in phage therapy [16].

Another obstruction could be a risk of particular species of micro-organism which may develop resistance to the bacteriophage [37]. However, this would be significantly less serious than the drug resistance problem as it would just reduce the efficacy of that one bacteriophage and there is the chance of the bacteriophage also adapting to overcome any resistance to it. They are much specific to one species of bacteria and there is very minor possibility of the bacteriophage damaging any

beneficial bacteria but still these things need to be verified through clinical trials. It has to be noted that decrease bacterial growth in critical time of illness allows the patient more time to recover from the SAR-CoV-2 infection [16].
