April 21 (UPI) -- The COVID-19 vaccines have provided the pandemic-weary public with a "light at the end of the tunnel," but the threat posed by the virus will not be over until more of the world has been immunized, public health researchers said Wednesday.
Although the United States already has vaccinated more than 40% of its population against the coronavirus, and countries such as Britain and Israel have inoculated well over half, other nations are lagging, according to vaccine expert Naor Bar-Zeev.
Countries such as Brazil and India, where COVID-19 cases are rising rapidly, for example, have given the vaccine to only about 10% of their citizens, based on estimates from the University of Oxford-associated Our World In Data, while nations in Africa and South America have vaccinated even fewer, he said.
"Why does it matter to people in United States that people in Ghana are vaccinated?" Bar-Zeev asked rhetorically during a teleconference with reporters.
"It relates to ongoing virus transmission and the emergence of variants. Countries with higher vaccinated populations will see less transmission and fewer variants," said Bar-Zeev, deputy director International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health in Baltimore.
Conversely, for countries in which active virus spread remains high, potentially dangerous variants will be more likely to emerge, according to his colleague, Dr. Anna Durbin, a professor of international health at the School of Public Health.
More than 31.6 million people across the country have been infected with the virus, and nearly 566,000 people have died as a result, the U.S. Centers for Disease Control and Prevention estimates.
The United States reported nearly 60,000 new cases Tuesday, a recent high, according to the agency.
Through Wednesday, more than 134.4 million people in the United States, or 41% of the population, had received at least one vaccine dose, including nearly 44 million adults age 65 and older, the CDC said.
In addition, more than 87.6 million people, or 26% of the population, are considered "fully vaccinated," meaning they have received both doses of the Pfizer-BioNTech or Moderna vaccines or the single-dose Johnson & Johnson inoculation.
Still, in the United States, even with a substantial portion of the population vaccinated, new variants of the coronavirus, including the B.1.1.7 or "U.K." strain, have emerged, according to the CDC.
If people in the United States are unable or unwilling to receive the vaccine, this could effectively delay the end of the pandemic, as fewer people with immunity will provide a platform for new coronavirus variants to develop, Durbin said.
Despite reports of potentially dangerous side effects associated with currently available vaccines -- severe allergic reactions in the case of the Pfizer-BioNTech and Moderna shots and blood clots with the Johnson & Johnson product -- these events are "extremely rare," she said.
Both Durbin and Bar-Zeev urged people in the United States to become vaccinated, and they called on the federal, state and local governments to take steps to ensure widespread access to the vaccine.
They said they also hope the country takes a leadership role in, and provides significant funding to, efforts to ensure vaccine access globally.
"Vaccines are providing us light at the end of the tunnel, but we will not be out of this pandemic until the entire world is vaccinated," Durbin said.