Banks including Goldman Sachs and Standard Chartered, who run much of their global back office operations from large office parks in Bengaluru, Chennai or Hyderabad, have put in place infrastructure to vaccinate thousands of employees and their families when age restrictions are lifted on May 1.
Workers at huge technology service providers Accenture, Infosys and Wipro say teams are working 13-14 hours daily, under growing pressure and struggling to deliver on projects as staff call in sick and take time off to care for friends and relatives.
They play down any threat of a collapse in operations - but at stake if the surge continues is the infrastructure put in place by the world's biggest financial companies in cost-cutting drives that have left them deeply reliant on the big Indian offices.
"Employees have contracted COVID-19 since the second wave began, causing severe pressure for projects that are nearing deadlines," said one employee at Accenture, asking not to be identified because he was not authorised to speak to the media.
Five other sources at Accenture confirmed the growing issues with pressure of work. Accenture said it was providing some medical care and covering the cost of vaccinations for its employees but did not comment on the impact on productivity.
Wipro said it has not seen any disruption to operations and has transferred some client projects to offices outside India.
Only about 3% of its nearly 200,000 employees are now working from the office on critical projects, and it expects more of those employees to work from home, it said. For those who have to work from the office, Wipro said it had made living arrangements at guest houses and hotels nearby.
Infosys, India's second largest software services firm, said it was operating remotely across all offices and had not seen any impact on client projects, despite the deteriorating health situation in the country in recent weeks.
Tata Consultancy Services, India's top information technology (IT) services firm, similarly said its operations had not been affected.
India's second wave of infections has seen at least 300,000 people test positive each day for the past week, overwhelming healthcare facilities and crematoriums and driving an increasingly urgent international response.
Asia's IT capital Bengaluru, desperate to calm a daily infection rate five times higher than in last year's first wave, on Monday ordered a full lockdown that allows ordinary residents to leave their homes only briefly between 6 a.m. and 10 a.m.
Local IT managers say they struggled to get global chiefs outside India to recognise the seriousness of the outbreak.
COVID-19 'WAR ROOMS'
India's gigantic IT and call centre service industry employs more than 4.5 million people directly and relies on huge numbers of graduates under the age of 30.
They are paid a fraction of Western salaries and had largely ridden out the COVID-19 pandemic working from home until the relaxing of restrictions in recent months spurred companies to call more employees back to the office.
Managers at Goldman Sachs' massive complex in Bengaluru, for example, told staff in early March to prepare to return to full-scale office working.
Chief Executive Officer David Solomon said then that the bank owed it to its incoming class of analysts and interns to have them come to work in offices for at least part of the summer. The company quickly U-turned, sending all but essential employees home on March 27 as cases began to rise.
Another large bank, Wells Fargo, said its employees in India would continue to work remotely till at least early September.
New strains of the virus have since sent India's case numbers soaring to global records and brought more infections among younger Indians.
All 15 of the large companies Reuters spoke to this week said that they now had vaccination schemes in place. Several outlined COVID-19 "war-rooms" they had launched to support staff and secure oxygen and other supplies.
Initially, managers outside India had not wanted their companies' Indian operations to be seen to be jumping the queue for vaccines, says a senior manager who runs a workforce of more than 600 staff at a global bank in Bengaluru, asking not to be identified.
"The India CEO and others here said: we don't care what it looks like, people are dying."
(Reporting by Sethuraman N.R., Anirban Sen, Noor Zainab Hussain, Sachin Ravikumar, Chandini Monnappa, Supriya Rangarajan, Aaron Saldanha, Anand Katakam, Subrat Patnaik and Chris Thomas in Bengaluru and Elizabeth Dilts in New York; writing by Patrick Graham; Editing by Michael Perry and Raju Gopalakrishnan)
By Sethuraman N R and Anirban Sen