Medical workers move a patient to the intensive care unit of Sotiria Hospital as part of the coronavirus disease (COVID-19) pandemic on March 1, 2021 in Athens, Greece.

Giorgos Moutafis | Reuters

World Health Organization officials said Wednesday that scientists are trying to understand why Covid-19 cases are suddenly popping up in much of the world after weeks of infection.

2.6 million new cases were reported worldwide last week, up 7% from the previous week, the WHO said in its weekly epidemiological update, which reflects data received on Sunday morning. That follows six consecutive weeks of declining new cases around the world.

The reversal could be caused by the emergence of several new, more contagious variants of the coronavirus, easing public policies and what is known as pandemic fatigue, where people are tired of taking precautionary measures, the WHO said in its weekly report. Maria Van Kerkhove, WHO director of emerging diseases and zoonosis, said Wednesday during a question and answer session at the organization’s headquarters in Geneva that the global health agency is trying to better understand what is reversing the trend in each region and each Land caused.

“I can tell you that we are concerned about the introduction of vaccines and vaccinations in a number of countries. We still need people to do their actions on an individual level,” she said, urging people to exercise physical distancing practice and continue wearing masks when they are around others.

“Given this week-long increase in trends, it’s a pretty stern warning to all of us that we need to stay on course,” said Van Kerkhove. “We must continue to adhere to these measures.”

Dr. Mike Ryan, executive director of the WHO’s health emergencies program, suggested the increase could be because “we may relax a little before we get the full effect of vaccination”. He added that he understood the temptation to socialize and return to more normal behavior, but “the problem is every time we did that before the virus took advantage of it.”

Ryan reiterated that the cause of the surge in the cases remains unclear, but added that the tried and tested public health measures highlighted during the pandemic are still in effect.

“When the cases are decreasing it’s never all we do and when they are increasing it’s never all our fault,” he said.

Ryan noted that deaths have not yet risen with the cases, but that could change in the coming weeks. Hopefully, vaccinating those most severely affected by the disease could prevent an increase in deaths.

While the introduction of vaccines in some countries gives cause for optimism, Ryan noted that many nations around the world have not yet received doses. He said 80% of the doses were given in just 10 countries.

WHO’s remarks are consistent with those recently made by federal officials in the United States. Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, has been warning for days that the decline in new cases every day in the United States has stalled and increased.

In the past seven days, the United States reported an average of more than 65,400 new cases a day, according to Johns Hopkins University. That’s well below the high of about 250,000 new cases per day the country reported in early January, but it’s still well above the infection rate the US saw the summer when the virus swept the sun belt.

“At this level of cases where variants spread, we will completely lose the hard-earned ground we won,” Walensky said on Monday. “With these statistics, I’m really concerned that more states are rolling back the exact public health measures we have recommended to protect people from Covid-19.”

“Please listen to me clearly: at this level of cases with spreading variant, we are going to completely lose the hard-earned ground we have gained,” she said.