LONDON — More than half of all adults in the United Kingdom have received a second dose of a COVID-19 vaccine, the latest figures published on Thursday showed, as the vaccination program continues at an unprecedented pace and scale. Health services across the UK have now administered a total of 66,180,731 vaccines between Dec. 8 and June 2, including 39,758,428 people with first doses (75.5 percent) and 26,422,303 people with both doses (50.2 percent), ensuring they have the strongest possible protection against COVID-19 from a second dose, the government said in a press statement. The government statement cited a recent study done by Public Health England (PHE) on the efficacy of vaccines, saying the study showed that 2 doses of the COVID-19 vaccines are highly effective against the B.1.617.2 (Delta) variant first identified in India. Vaccine effectiveness against symptomatic disease from the B.1.617.2 (Delta) variant is similar after 2 doses compared to the B.1.1.7 (Alpha) variant dominant in the UK, the statement added. Commenting on the passing of a major milestone, UK Health and Social Care Secretary Matt Hancock said: "Shortly after vaccinating three-quarters of adults with a first dose, I’m thrilled that we have now vaccinated over half of adults with the life-saving second dose." "We know how important the second dose is to give protection, particularly against the Delta variant. That’s why we’ve brought forward appointments from 12 to 8 weeks for the most vulnerable people, he added, calling on those who are inoculated against the virus to come forward and get the vaccines. Meanwhile, UK"s Vaccines Minister Nadhim Zahawi, said: "Over half of UK adults have now been fully vaccinated and have maximum protection against this awful virus, which is heart-warming news." "Everyone who has received their second dose can breathe a huge sigh of relief knowing that they have the ultimate protection from the virus and the new variants." "We have come an incredibly long way in just under 6 months with our vaccination program. But our work is not done yet. If you’ve had one dose, please come back for your second jab when you get the offer, the minister added. Vaccinated people are far less likely to get COVID-19 with symptoms. Vaccinated people are even more unlikely to get serious COVID-19, to be admitted to hospital, or to die from it and there is growing evidence that vaccinated people are less likely to pass the virus to others.