More than 137,000 people in Britain have received a first dose of the Pfizer-BioNTech COVID vaccine in the week since inoculations began, the government announced on Wednesday.
The Department for Health and Social Care said 137,897 people had received the jab since December 8. Of those, 108,000 were in England, the most populous of the UK's four nations.
Prime Minister Boris Johnson told lawmakers he was "very pleased" with the "good start with the rollout of the vaccination".
The Pfizer/BioNTech vaccine was the first coronavirus shot to be authorised for use by the UK's independent medicines regulator. Patients require two doses, 21 days apart.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
Britain has ordered 40 million doses of the jab -- enough to vaccinate 20 million people -- with 800,000 in the first batch.
First in line are people aged 80 and above, and frontline health and social care workers.
The vaccination programme was this week expanded into doctors' surgeries in England, and in care homes in Scotland.
The bulk of Britain's vaccine requirements are expected to be met by a jab developed by AstraZeneca and the University of Oxford, which is awaiting regulatory approval.
Some 100 million doses have been ordered. The government has also ordered seven million of vaccine developed by Moderna.
Britain has been one of the worst-hit countries in Europe by the virus with nearly 65,000 deaths from some 1.9 million cases.
On Wednesday, London and surrounding areas were placed under stricter measures to curb the spread of the virus because of concern about a rise in cases.Follow our full coverage of the coronavirus pandemic here.