ZURICH (Reuters) – The number of new coronavirus infections globally rose last week for the first time in seven weeks, the World Health Organization said on Monday.

“We need to have a stern warning for all of us: that this virus will rebound if we let it,” Maria Van Kerkhove, the WHO technical lead for COVID-19, told a briefing. “And we cannot let it.”

WHO Director-General Tedros Adhanom Ghebreyesus said the rise in cases was “disappointing but not surprising” and urged countries not to relax measures to fight the disease.

It was too early for countries to rely solely on vaccination programs and abandon other measures, he said: “If countries rely solely on vaccines, they are making a mistake. Basic public health measures remain the foundation of the response.”

Tedros noted that Ghana and Ivory Coast became the first countries on Monday to begin vaccinating people with doses supplied by COVAX, the international program to provide vaccines for poor and middle-income countries.

But he also criticized rich countries for hoarding vaccine doses, saying that it was in everyone’s interest for vulnerable people to be protected around the world.

“It’s regrettable that some countries continue to prioritize vaccinating younger healthier adults at lower risk of diseases in their own populations, ahead of health workers and older people elsewhere,” Tedros said.

Mike Ryan, the WHO’s top emergency expert, said the global fight against the coronavirus was in a better state now than it was 10 weeks ago before the roll-outs of vaccines had begun. But it was too early to say the virus was coming under control.

“The issue is of us being in control of the virus and the virus being in control of us. And right now the virus is very much in control.”

(Reporting by John Revill, Vishwadha Chander, Manojna Maddipatla; Writing by Peter Graff; Editing by Alex Richardson, Dan Grebler and Giles Elgood)