Bristol-Myers Squibb Co will require all its employees working in the United States and Puerto Rico to be fully vaccinated against the coronavirus effective Nov. 1, the drugmaker said on Tuesday.

In the face of a resurgence in COVID-19 cases, spurred by the highly contagious Delta coronavirus variant, many U.S. companies have come out with mask mandates and changed their vaccination policies.

Bristol-Myers joined a slew of companies such as Centene Corp, Cigna Corp and Microsoft Corp across the healthcare, technology and financial sectors in mandating vaccines or tests for employees working from office.

More than 85% of its employees in the United States and Puerto Rico have already been vaccinated against COVID-19, Bristol-Myers said, adding that it continues to require weekly asymptomatic testing, mask wearing, and physical distancing of all staff onsite.

Vaccine Mandates for Half of U.S. Businesses

According to a recent national survey, more than half of U.S. companies are planning to impose COVID-19 vaccine mandates in the workplace by year end.

Bristol-Myers also said it had not seen any disruption in its clinical or commercial supply chain due to the pandemic. (Reporting by Mrinalika Roy in Bengaluru)