Nearly 5 million people have died of covid-19 since the start of the pandemic

Nearly a quarter billion cases of the coronavirus have been reported. Despite the rollout of vaccines, global health experts warn that the pandemic is set to continue.

"With almost 50,000 deaths a week, the pandemic is far from over - and that's just the reported deaths," World Health Organization Director General Tedros Adhanom Ghebreyesus said at the World Health Summit in Berlin on Oct. 24.

Vaccines have blunted the worst impact of the pandemic in many countries, though their distribution has been marked by inequities that has meant they have not stopped the virus's spread.

China leads the world in the number of vaccine doses administered, though some other nations have vaccinated a greater share of their population. A number of vaccines were developed and rolled out at record speed, and studies show most have impressive efficacy.

Billions of doses have been administered around the world, far more than the number of confirmed cases of the coronavirus since the start of the pandemic - though a large number of cases were probably never recorded, experts caution.

But the vaccine rollout has faced problems with global supply and pockets of opposition in many nations. Covax, a program backed by the World Health Organization to fairly distribute vaccines, only belatedly began distributing doses to low-income nations.

"I can't say it's surprising," said Thomas J. Bollyky, a senior fellow at the Council on Foreign Relations, earlier this year. "In every previous pandemic where we have our global health crisis, where there has been limited supplies of medical intervention, wealthy nations have hoarded."

The United States continues to have the highest cumulative number of confirmed cases and deaths globally. In early October, the U.S. death toll from covid-19, the disease caused by the virus, surpassed 700,000, despite the widespread availability of vaccines in the country.

Behind the United States, Brazil, India, Mexico and Russia have the largest cumulative numbers of cases.

India's record-setting surge in spring 2021 meant that the country accounted then for about 1 in 3 of all new confirmed cases. The spike, which was blamed on complacency and the lifting of restrictions, along with the spread of variants, saw the country's health-care system overwhelmed amid widespread oxygen shortages. Even after the surge in new cases subsided in mid-May, India still set records for the number of new daily deaths, with more than 4,500 deaths from covid-19 reported in a single 24-hour period.

In India, as in Britain and Brazil before it, the spread of the virus was blamed on fast-spreading variants rampant in the country, including the delta variant that was first identified in India.

Delta, also known as B.1.617.2, has become the dominant variant in many parts of the world. The variant is more virulent than many others and studies have shown that vaccines do not provide the same levels of protection against it, though they do still significantly reduce the likelihood of serious illness.

Some countries have seen success at controlling the virus - at a price.

In New Zealand, which closed its borders and ordered people to stay home as a first wave hit in the spring of 2020, confirmed that infections went down to zero for a time. Taiwan and Singapore have kept their outbreaks far smaller than those in other parts of the world, which some experts attribute to their early responses and sophisticated tracking and tracing.

China, the early epicenter of the crisis, has seen much of daily life return to normal. In the early months of the outbreak, it reported more cases than any other country. Its tally of new infections peaked in mid-February of 2020 and approached zero by mid-March of that year, although questions surround the accuracy of its data.

But maintaining these "zero covid" policies for almost two years has proved difficult. New Zealand Prime Minister Jacinda Ardern said this month that the country would phase out its pursuit of zero coronavirus cases and instead manage the spread of the virus through vaccines and "everyday public health measures" to keep residents safe.

"The Chinese government is keeping a close eye on what is happening overseas to work out whether giving up a 'zero covid' policy requires accepting a spike in cases," Huang Yanzhong, a senior fellow for global public health at the Council on Foreign Relations, told The Washington Post in October. "That prospect is not acceptable for China."

Countries that have successfully rolled out vaccines are also seeing gains. Britain, one of the hardest-hit countries in terms of cases and deaths, has excelled in the distribution of vaccine doses. It was the first country to roll out a fully tested vaccine to the general public in December, when it began distributing the vaccine developed by Pfizer.

Data released by Public Health England in March suggested that vaccinations had saved over 6,000 lives among people over 70, if not more.

But vaccinations have not ended the pandemic in Britain. Cases have risen since the country dropped its last remaining restrictions in July, despite high levels of vaccination across the country. Some scientists have suggested waning immunity from doses administered in the spring.

Though the WHO has officially called for a moratorium on "booster" shots for those already fully vaccinated, many nations around the world have begun rolling out the shots as official policy for at least part of their population - including the United States.

The new demand from high-income countries for both booster shots and vaccines for children has furthered the competition for doses, often leaving low- and middle-income nations further down the line. The WHO-backed Covax effort has struggled with supply and funding issues.

Only five African countries out of 54 are expected to hit the target of vaccinating 40 percent of their population by the end of the year, according to data from the WHO. Experts say the spread of the virus in countries with little protection from vaccines could lead to more variants and prolong the pandemic.

"Vaccine inequity is not just holding the poorest countries back - it is holding the world back," Henrietta Fore, executive director of UNICEF, said in a statement released Oct. 27.