This editorial appeared on Bloomberg Opinion.

The rise of the dangerous delta variant of the coronavirus gives new urgency to the effort to get people vaccinated. Delta has been spreading phenomenally fast. It's already the dominant strain in India, the U.K. and Singapore, and it has a foothold in more than 80 countries. While it accounts for only about 10% of U.S. cases of COVID-19 so far, that share is expected to balloon.

There's evidence, too, that the variant may cause more severe disease. Data from the U.K. suggest people who contract this strain are twice as likely to be hospitalized as those who caught a previous form of the coronavirus.

The saving grace is that vaccines keep people safe.

This makes it more urgent than ever to expand vaccination. So far, public-health leaders and many business owners have tried coaxing − patiently explaining the benefits of vaccination, giving away burgers and doughnuts, holding big prize lotteries, and sending mobile vaccination units to underserved neighborhoods. Thanks in part to these efforts, 65% of American adults have now had at least one shot. But that share needs to grow. It's thought that at least 70% of the population needs to be fully vaccinated to keep infection rates down without other social restrictions. At this point, stronger measures are needed.

Major sports leagues are right, for example, to demand proof of vaccination from people who attend games. Universities should also make sure students and professors have their shots. Companies should begin to exercise their authority to require employees to be vaccinated before entering the workplace. Hospitals and other health-care centers have a special responsibility to make sure their workers are vaccinated.

Regrettably, several states have actively hampered such efforts. A new law in Texas goes so far as to deny state contracts to businesses that demand their customers be inoculated and threatens to yank operating permits. In Florida, where state law prohibits schools, businesses and government agencies from demanding proof of Covid vaccination, Governor Ron DeSantis has refused to grant an exemption even to cruise ship operators, who can hardly assure passengers that they're safe without requiring vaccines.

Such stubbornness is foolish and dangerous; all the more so with the delta variant on the rise.