Stars and Stripes is making stories on the coronavirus pandemic available free of charge. See more stories here. Sign up for our daily coronavirus newsletter here. Please support our journalism with a subscription.

"The virus is running freely," the World Health Organization warns as the latest omicron offshoots drive up coronavirus infections around the world.

Many countries have lifted restrictions and reduced coronavirus tracking as they grapple with pandemic fatigue. But "new waves of the virus demonstrate again that COVID-19 is nowhere near over," according to WHO chief Tedros Adhanom Ghebreyesus.

He appealed to governments Tuesday to pour efforts back into testing and improving vaccine deployment and said rising cases were straining medical systems already stretched by the pandemic.

The WHO's call to action echoed concerns from U.S. health officials, who urged Americans on Tuesday to take precautions against reinfection and serious illness. Biden administration officials are seeking to contain the spread with vaccinations, antivirals and testing, as they develop a plan to offer all adults a second booster shot.

Federal data indicates that the BA.4 and BA.5 subvariants make up about 80% of circulating coronavirus in the United States, where 67% of people have been fully vaccinated.

Britain, which has vaccinated much of the population and lifted all coronavirus curbs, including masking and requiring those who test positive to self-quarantine, is also facing a virus surge. In Britain, 1 in 25 people had COVID-19 during the week ending June 29, the latest government statistics estimated.

The country is now allowing a second booster shot for people older than 75 and others with weakened immune systems.

A virus surge across Europe prompted health regulators on the continent to recommend a second booster for high-risk groups this week as part of efforts to fight the subvariants.

"A new COVID-19 wave is ramping up across the European Union," the European Center for Disease Prevention and Control said Monday in a statement. It urged governments to prepare "for a next expected wave in the autumn and winter seasons."

In China, the arrival of the BA.5 subvariant raised fears of a return of lockdowns in Shanghai, where many residents have just emerged from two months of home confinement.

Health experts say the spread of the variants highlights the need to immunize populations that remain unprotected because of vaccine apathy or unequal access. More than 12 billion coronavirus shots have been administered worldwide, but in low-income countries, only about 19% of people have received at least one dose, according to Our World in Data.

In Tuesday's briefing, the WHO director general also said countries are "not effectively managing … the expanding number of people" with long COVID — which refers to ongoing or new health problems that occur at least four weeks after infection.

While vaccines and other health tools put the world in a better position than the early pandemic days, "we should not take them for granted," Tedros said. "As the virus pushes at us, we must push back."