Coronavirus cases worldwide surpassed 200 million on Wednesday, according to a Reuters tally, as the more-infectious Delta variant threatens areas with low vaccination rates and strains healthcare systems.

The global surge in cases is highlighting the widening gap in inoculation rates between wealthy and poor nations. Cases are rising in about one-third of the world’s countries, many of which have not even given half their population a first dose.

The World Health Organization (WHO) on Wednesday called for a moratorium on COVID-19 vaccine boosters until at least 10% of the population in every country was vaccinated. read more (Graphic on global vaccinations)

“We need an urgent reversal, from the majority of vaccines going to high-income countries, to the majority going to low-income countries,” WHO Director-General Tedros Adhanom Ghebreyesus said.

The Delta variant is upending all assumptions about the virus and roiling economies, with disease experts scrambling to find whether the latest version of coronavirus is making people, especially unvaccinated individuals, sicker than before.

At least 2.6% of the world’s population has been infected since the pandemic started, with the true figure likely higher due to limited testing in many places. If the number of infected people were a country, it would be eighth most populous in the world, behind Nigeria, according to a Reuters analysis.

It took over a year for COVID-19 cases to hit 100 million mark, while the next 100 million were reported in just over six months, according to the analysis. The pandemic has left close to 4.4 million people dead.

The countries reporting the most cases on a seven-day average – the United States, Brazil, Indonesia, India and Iran – represent about 38% of all global cases reported each day.

The United States accounts for one in every seven infections reported worldwide. U.S. states with low vaccination rates such as Florida and Louisiana are seeing record numbers of COVID patients hospitalized, despite the nation giving 70% of adults at least one vaccine shot. The head of one Louisiana hospital warned of the “darkest days” yet. read more

Unvaccinated people represent nearly 97% of severe cases, according to the White House COVID-19 Response Team.