The Delta variant is estimated to be more than twice as transmissible as the original Covid strain that emerged from Wuhan. Australia reports that several people were infected after “fleeting” contacts in a shopping mall. U.S. Covid cases have tripled in a month, as states lifted restrictions and travel rebounded. In the U.K., which has among the highest vaccination rates in the world, cases are approaching their winter peak.

Previously infected individuals appear to be more susceptible to re-infection by the Delta variant, which could explain some of the rising cases. The Pfizer vaccine is also estimated to be 10% to 30% less effective at preventing symptomatic illness, which means more infections among the vaccinated. Chinese vaccines appear to be less effective, and many developing countries that took the Chinese shots are administering booster shots by Western manufacturers.

But none of this is cause for Covid panic or more lockdowns. Vaccines are still highly effective at preventing severe illness, which is why hospitalizations in the U.K. have increased much less than cases. Some 99% of hospitalized Americans now are among the unvaccinated. Most vaccinated people with new infections—such as the five Texas Democratic state lawmakers who fled to Washington, D.C., last week—experience cold-like symptoms.