Nice study, I don't find any mayor fail. (Some articles are very bad.)
As they say, it's not a double-blind randomized controlled trial.
I like more the pilot study because they try to match the age and pupation of the both groups. The problem is that they perhaps involuntary cherry picked the sublets in the experimental group. For example if there are 50 nurses and they want to recruit some of them, they may go first with with the ones that fill all the paperwork so they don't mess with the data for the study, or they skip the one that is drunk every other Monday or the one that is 15 minutes late everyday. Do these involuntary selection affect the result? Perhaps. Did they do this involuntary selection? Perhaps??? How can it be solved...
Make a double-blind randomized controlled trial. They can involuntary cherry pick and this is fixed by the randomization.
Also double-blind, because if you are the subject of the study, you don't want to "fail" and you are more careful. Or not. But just in case double-blind.
In the first study it's not clear how they got the control group. Perhspa go to HR, ask for the complete list, and then choose some randomly.
The second one is more weird, because
> A total of 1,195 health care workers were recruited from 4
major hospitals ... 788 participants received IVERCAR and PPEs, while
the remaining 407 simply adhered to standard PPEs.
It's very unclear how they split them.
Another weird details is that
> Received date: November 09, 2020; Accepted date: November 16, 2020;
It's a very short review period. Perhaps it's common in the area, but in many areas the reviewers take like a month or more. I'm not sure if it's a good or bad journal. It's very difficult to know that if you are not in the area.