Scientists initially estimated that 60 percent to 70 percent of a population would have to acquire resistance to Covid-19 in order for herd immunity to take effect, a threshold that has been revised upwards since the start of the year with 80 percent to 85 percent quoted in some cases, according to a recent feature in Statista.com. The race towards full vaccination is well underway and Israel has the highest share of its population fully jabbed, according to Our World in Data.

Despite the ever-higher immunity threshold discussed by scientists, Israel's Covid-19 case count started to tumble when 40 percent of its population received at least one jab and now 57.9 percent of its inhabitants are fully vaccinated. The country's reproduction rate has been around 50 in recent weeks and it appears to be on track to emerge from the pandemic, suggesting that initial herd immunity estimates carried some accuracy.

With 27.7 percent of its inhabitants fully vaccinated, Chile comes second on the list, just ahead of Bahrain with 27.2 percent. In the U.S., the CDC announced that 50 percent of adults had received at least one jab while around a quarter of people have been fully vaccinated. In this case, full vaccination refers to all doses prescribed by the vaccination protocol with data only available for countries reporting the breakdown of their doses.