The surge in coronavirus cases 2019 (Covid-19) in India will affect the worldwide supply of Covid-19 vaccines as the country is a major vaccine producer and a critical supplier to the United Nations (UN)-backed COVAX initiative.

COVAX aims to bring shots to some of the world’s poorest countries. Already the rise in cases has forced India to focus on satisfying its domestic demand — and delay deliveries to COVAX and elsewhere, including the United Kingdom and Canada.

India’s decision “means there is very little, if anything, left for COVAX and everybody else,” said Brook Baker, a vaccines expert at Northeastern University.

When infections began plummeting in India in September, many concluded the worst had passed. Masks and social distancing were abandoned, while the government gave mixed signals about the level of risk. When cases began rising again in February, authorities were left scrambling.

“Nobody took a long-term view of the pandemic,” said Dr. Vineeta Bal, who studies immune systems at the city’s Indian Institute of Science Education and Research. She noted, for instance, that instead of strengthening existing hospitals, temporary sites were created. In Pune, authorities are resurrecting one of those makeshift facilities, which was crucial to the city’s fight against the virus last year.

India is not alone. Many countries in Europe that saw declines in cases are experiencing new surges, and infection rates have been climbing in every global region, partially driven by new virus variants.

Over the past week, India had averaged more than 130,000 cases per day. It has now reported 13.5 million virus cases since the pandemic began — pushing its toll past Brazil’s and making it second only to the United States’, though both countries have much smaller populations. Deaths are also rising and have crossed the 170,000 mark. Even those figures, experts say, are likely an undercount.

The country now faces the mammoth challenge of vaccinating millions of people, while also contact-tracing the tens of thousands getting infected every day and keeping the health system from collapsing.