The European Union, Canada and other developed countries have signed deals to get hundreds of millions of doses of Covid-19 vaccines and boosters over the next two years, furthering a divide between rich and poor countries. Under the recent deals, Pfizer Inc. PFE 0.75% and BioNTech BNTX 6.43% SE agreed to supply the European Union up to 1.8 billion doses of their vaccine through 2023, while agreeing to supply Canada up to 125 million doses.

Australia, Switzerland and Israel, meanwhile, are set to get Moderna Inc.’s MRNA 3.76% shot through next year, and Switzerland has options for doses in 2023. The agreements will ensure the countries, including some that failed to lock up sufficient supplies of the mRNA vaccines earlier this year, have enough supplies to inoculate residents and protect them against potentially elusive variants, while providing a sales windfall to the manufacturers.

Yet the deals once again leave out developing countries, many of which have fallen behind in vaccinating residents and struggled to contain the spread of the virus.

Moderna sees Covax, the global-health initiative intended to get doses to low-income countries, as its primary means to supply lower- and middle-income countries, a spokesman said. The company said last month it would deliver 34 million doses in the fourth quarter of 2021 to Covax, which has an option to purchase another 466 million doses next year.

Pfizer has pledged to provide 2 billion doses to low- and middle-income countries over the next 18 months, a company spokeswoman said. It also has agreed to provide 40 million doses to Covax this year for distribution, which have begun to reach more than a dozen countries, she said. Pfizer’s commitment to ensure access to the vaccine “has never wavered,” and it is talking with countries and stakeholders about improving access, she added.

About 6 billion doses have been purchased by more than two dozen rich nations and the European Union, according to the latest figures from the Duke University’s Global Health Innovation Center, which tracks vaccine purchases. By comparison, the rest of the world has combined to purchase more than 3 billion doses.