U.K. health authorities rolled out the first doses of a widely tested and independently reviewed COVID-19 vaccine Tuesday.

The first recipient was Margaret Keenan, who turns 91 next week. The former jewelry shop assistant received the shot at University Hospital Coventry at 6:31 a.m. The second injection went to a man named William Shakespeare, an 81-year-old who hails from Warwickshire.

“I feel so privileged to be the first person vaccinated against COVID-19,” she said. “It’s the best early birthday present I could wish for because it means I can finally look forward to spending time with my family and friends in the New Year after being on my own for most of the year.”

“Today is just the first step in the largest vaccination program this country has ever seen,” said Simon Stevens, head of England’s National Health Service. “It will take some months to complete the work as more vaccine supplies become available … but if we all stay vigilant in the weeks and months ahead, we will be able to look back at this as a decisive turning point in the battle against the virus.”

The first 800,000 doses are going to people over 80 who are either hospitalized or already have outpatient appointments scheduled, along with nursing home workers. Others will have to wait their turn.

The U.K. is the first Western country to start a mass vaccination program after British regulators last week authorized the use of a COVID-19 shot developed by U.S. drugmaker Pfizer and Germany’s BioNTech. U.S. and European Union regulators may approve the vaccine in the coming days or weeks, fueling a global immunization effort.