Not working in POST Request of backend Nodejs application.(MERN Stack)

[Namasivaayam-L]

The Question:
I am developing a disease prediction website. I have used react for frontend and express, mongodb, nodejs for backend. If run the python script just by executing the .js (file containing the Python-Shell code) file it works just fine. But if I run .js file in a post request in nodejs when a webpage loads in react frontend using useEffect the python script is not executing.

Any relevant python/javascript code:
JAVASCRIPT(NODEJS)

1. const {PythonShell} = require('python-shell')
2. const router = require('express').Router()
3. const spawn = require('child_process').spawn
4. router.post('/', async(req, res ) => {
5.     //METHOD -1 (Not Working)
6.     try {
7.         options = {
8.             pythonPath: 'C:\\Users\\default\\AppData\\Local\\Programs\\Python\\Python39\\',
9. 
10           args: [req.body[0]],                                //req.body[0] indicates the command line argument for the python program
11
.             scriptPath:'C:\\Users\\default\\Documents\\getSymptoms.py'  //path of my .py file
12.         };
13.         PythonShell.run('./getSymptoms.py', options, function (err, results) {
14.             if (err) throw err;
15.             return res.send(results);
16.         });
17. 
18.        //METHOD -2 (Not working too)
19.        var output
20.         const python = spawn('python.exe', ['./getSymptoms.py',req.body[0]])
21.         // PART-1 (Not working)
22.         python.stdout.on('data', function (data) {
23.             console.log('Pipe data from python script ...');
24.             output = data.toString();
25.         });
26.         //PART-2 (***WORKING***)
27.         python.on('close', (code) => {
28.             console.log(output);
29.             console.log(`child process close all stdio with code ${code}`);
30.             // send data to browser
31.             return res.send(output);
32.         });
33.         }
34.             catch (error) {
35.                 return res.send({ message: "Error" });
36.         }
37.     })
38. module.exports=router    
39. 

PYTHON FILE
print(sys.argv[1])