first.component.ts

import { Component, OnInit } from "@angular/core";
import { CommsService } from "../comms-service.ts";

@Component({
...
})
export class FirstComponent implements OnInit {
  listStatus;
  constructor(public _commService: CommsService) {}
  ngOnInit() {
    this._commService.waitingListStatus.subscribe(
      (res: boolean) => {
        this.listStatus = res;
      }, (err: Error) => {
        console.log("Error", err);
      }
    )
  }
  
  updateListStatus(status) {
    this._commService.updateWaitingListStatus(status);
  }
}