By Newley Purnell India s giant outsourcing firms are facing a two-front challenge: protecting the health of millions of employees as the nation suffers the world s worst Covid-19 crisis, and ensuring that their work continues as usual for the big Western companies on their client lists. Companies like Infosys Ltd., Wipro Ltd. and Tata Consultancy Services Ltd., known as TCS, have built up armies of workers who serve global clients like Bank of America Corp., Citigroup Inc. s Citibank and Vanguard Group, doing everything from running call centers to writing computer code. The companies, along with Western tech businesses with large India-based staffs, are dealing with absences of sick workers, trying to help stricken employees find oxygen and getting vaccine shots for others at a time when such resources are scarce.