Close to 2 billion doses of COVID-19 vaccines have been administered worldwide as of June 1. More than 295 million doses, or 1.32 million per day, have been administered in the United States, which is behind only Chile in its percentage of vaccinated citizens.

In the US, the successful vaccine rollout has allowed some aspects of society to return to normal. NHL stadiums have hosted thousands of fans, while the NFL expects to have stadiums at full capacity for the upcoming 2021 season. But when can Americans expect a full return to pre-pandemic normalcy?

A 70 Percent Target Rate

Most experts have suggested that at least 70 percent of people in the US will either need to be vaccinated against or have recovered from COVID-19 to achieve herd immunity and stop the spread. Dr. Anthony Fauci, the chief medical advisor to the president, has stated that herd immunity might not be achieved until 85 percent of people are immune to the virus.

Vaccine Milestones

The US Centers for Disease Control and Prevention announced on May 25 that nearly half of all Americans (164,378,258 people) had received at least one dose of either the Moderna, Pfizer/BioNTech, or Johnson & Johnson vaccines. It also noted that 50 percent of all citizens 18 years and older had been fully vaccinated. Five states, including Maine and Massachusetts, had more than 50 percent of their population fully vaccinated as of May 30. Thirteen states, however, had fewer than 35 percent of their population fully vaccinated.

Vaccine Hesitancy

Dr. Leana Wen, a medical analyst with CNN, is one of the many herd immunity skeptics in the US. There are several impediments to achieving herd immunity, most notably vaccine hesitancy and the fact that just one of the vaccines (Pfizer-BioNTech) is approved for children as young as 12. The other two have yet to be approved for children 16 and younger. While they are undergoing clinical trials with children, Dr. Fauci doesn't anticipate approval for use until early 2022. Children 16 years and younger comprise roughly 25 percent of the US population, so achieving a vaccination rate of 85 percent is impossible without this approval.

Moreover, a survey conducted by the Kaiser Family Foundation found that 15 percent of Americans would “definitely not” get a vaccine, while 9 percent would only get vaccinated if required by their employer or school. Many people also have religious objections to vaccines. A March Associated Press survey showed that 40 percent of White evangelical Christians don't plan on getting vaccinated. Similarly, 42 percent of Republicans are hesitant about receiving the shot.