The approval comes as the nation faces the largest summer wave of COVID-19 cases in two years.
Pfizer announced Saturday that tweaking its COVID-19 vaccine to better target the omicron variant is safe and works — just days before regulators debate whether to offer Americans updated booster shots this fall.
In addition, daily health screens will come to an end Feb. 28, except for employees in California, New York and Virginia, the company said.
First announced in November, the mandate would affect all private businesses that employ more than 100 people. It would cover about 84 million Americans.
In the state of Indiana, more than 8 million COVID-19 vaccines have been administered and nearly 3.5 million Indiana residents are full vaccinated.
Until Wednesday, Kentucky was following guidance from the U.S. Centers for Disease Control and Prevention.
Indiana is also considering a lawsuit over what Gov. Holcomb calls "overreach" of the government's role.
The Federal Register will publish within days the Labor Department's rule requiring private businesses with 100 or more employees to vaccinate them or test them weekly, fulfilling an announcement President Joe Biden made in September.
Indiana ranks 41st of the 50 states according to percentage of total population that has been fully vaccinated, according to Centers for Disease Control and Prevention data.