Seven Charts That Explain the COVID-19 Pandemic in 2021

The rollout of safe and effective vaccines at the start of this year marked a turning point in a pandemic that wrought devastation for much of 2020. But 2021 still brought daunting challenges, including fears about omicron and other new variants, mounting death tolls and continued strain on health-care systems, and stark inequity in vaccine access across countries. Here are seven graphics that show what course the COVID-19 pandemic took over the past year and how the world responded.

Delta Brings Devastation

By midyear, one variant—given the name delta—had quickly become the dominant strain worldwide. The variant was first identified in India, where it sent the country spiraling into one of the world’s worst outbreaks of the pandemic. Evidence has shown delta to be more than two times as contagious as the original strain first discovered in Wuhan, China. Some data suggests that delta also causes more severe illness in unvaccinated individuals, though scientists are continuing to study how the strain behaves.

COVID-19 Becomes Leading Killer

People around the world grieved loved ones lost to COVID-19 as the disease became the fourth leading cause of death globally, writes Think Global Health, an initiative of CFR and the University of Washington. In the fall, the death toll surpassed five million people, including roughly 750,000 in the United States, the highest fatality figures in the world. Experts believe these numbers to be significant undercounts, and some estimate the global death toll to be twice as large. COVID-19 was the leading killer in most of Western Europe and Latin America, including in Brazil and Mexico, which rank in the top five for cumulative deaths from the disease. At the top of that list is the United States, where COVID-19 accounted for more than 11 percent of all deaths since the start of the pandemic.

Vaccines Put to the Test

More than half a dozen vaccines, mostly from China and the West, have been approved for broad use in different parts of the world. They’ve proven highly effective at protecting immunized individuals from hospitalization and death due to COVID-19, even with the spread of delta and other variants. So even amid new waves of infections, countries with relatively high proportions of vaccinated people—such as the Netherlands and the United Kingdom—have not experienced the spikes in COVID-19 deaths seen in those with low vaccination levels. Evidence also shows that these widely used vaccines can reduce the risk of infection, though scientists are still working to determine how long that protection lasts.

Rich Nations Slow to Follow Through on Donations

Only after wealthy nations made considerable progress immunizing their populations in the first half of the year did promises of donations to poorer countries start to ramp up. As of November 2021, countries had committed to donating a combined 2.74 billion doses, around 70 percent of which was promised by the United States and China. (Some countries, particularly in Europe, have opted to donate funding to the global COVAX initiative rather than doses.) But countries have been sluggish to follow through on their promises, Think Global Health finds: less than half of pledged doses had been delivered by the end of November. The United States has focused its efforts on parts of Asia and Latin America, while China has donated primarily to countries participating in its Belt and Road Initiative.

Global Vaccination Divide Grows

By November, half of the world had received at least one vaccine dose. Yet, a wide gap emerged between the vaccination rates of higher-income countries and lower-income ones, exacerbated by the slow pace of donations. Across all low-income nations at that time, just 4 percent of people were at least partially vaccinated. However, some have bucked the trend, such as Cambodia, where more than three-quarters of residents have been immunized.

The Debate Over Boosters

The global vaccination divide has driven intense debate about when and how to administer booster shots for COVID-19. As scientists continue to study how long different vaccines provide protection, some health officials and leaders around the globe have argued that the large number of unvaccinated individuals should be prioritized for doses before vaccinated people get boosters. By year’s end, some countries, including the United States, China, and members of the European Union, were already administering boosters despite the calls to prioritize the unvaccinated. A global rollout of boosters could mean another monumental supply challenge, Think Global Health shows: boosters just for immunocompromised people will require an additional 150 million doses; widening the criteria to anyone over the age of sixty increases that number to over one billion.

Fears About New Variants Persist

As the year neared to a close, fresh fears arose about the potential for new strains to take hold, including the omicron variant, which was first reported by South Africa in November. Scientists flagged omicron due to its high number of mutations, which could affect factors such as how easily it spreads and the severity of illness it causes, though researchers are in the early stages of studying its behavior. Its emergence led dozens of countries to reinstate restrictions on foreign travel, largely from southern Africa, and prompted calls to ramp up global vaccinations. A highly infectious variant carries significant risk for unvaccinated or partially vaccinated communities, as it can increase hospitalizations and overall strain on health-care facilities. In this way, a more infectious strain could lead to a higher death toll than a more lethal one would.

Melissa Manno contributed to this article.