Britain became the first country to vaccinate its population with Oxford University and AstraZeneca’s Covid-19 shot on Jan. 4, but Prime Minister Boris Johnson was set to tighten restrictions in England in a bid to slow the spread of cases.

Britain on Dec. 30 became the first country in the world to approve the coronavirus vaccine developed by Oxford University and AstraZeneca, hoping that rapid action will help it stem a record surge of infections driven by a highly contagious form of the virus.

Countries across the globe shut their borders to Britain on Dec. 21 due to fears about a highly infectious new coronavirus strain, causing travel chaos and raising the prospect of food shortages days before Britain is set to leave the European Union.

AstraZeneca said on Monday the company’s Covid-19 vaccine could be as much as 90% effective, giving the world’s fight against the global pandemic a new weapon, cheaper to make, easier to distribute and faster to scale-up than rivals.

The number of reported global daily deaths from the coronavirus reached 10,816 on Nov. 17, according to a Reuters tally, the highest single-day death count as the virus’ global epicenter the United States entered winter.

An experimental coronavirus vaccine being developed by AstraZeneca and the University of Oxford was safe and produced an immune response in early-stage clinical trials, data showed, keeping alive the hope AZD1222 could be in use by the end of 2020.

The United Kingdom’s COVID-19 death toll exceeds 40,000, by far the worst yet reported in Europe, raising more questions about Prime Minister Boris Johnson’s handling of the coronavirus crisis.