Covid: Hancock hails 'huge' day for vaccines across UK - BBC News
The UK has now delivered more than 60m vaccines, after 762,361 were given on Saturday.
Herd immunity is a term used to mean that most people are immune to a particular disease.

This means the disease is much less likely to spread from person to person, so those who are not immune are at reduced risk of illness.

The more infectious a disease is, the greater the number of people that need to be immune in order to reach the threshold where the unprotected are safe.

There are two ways of achieving herd immunity: the first is through the natural progression of the disease, which will cause illness and death as people become infected.

The second is through vaccination. The head of the UK Health Security Agency and test and Trace boss, Dr Jenny Harries, said this morning that around 70% of the population were now immune - mostly as a result of the vaccination programme but also as a result of infection.

But early on in the pandemic, the government’s chief scientific adviser, Sir Patrick Vallance, created alarm when he talked about herd immunity building up through the natural progression of the disease.

"Our aim," he said, "is to try and reduce the peak - not suppress it completely, also because most people get a mild illness, to build up some degree of herd immunity whilst protecting the most vulnerable."

Some interpreted his words as suggesting that it was government policy to create herd immunity by allowing the disease to spread - which is why it had not ordered a lockdown, despite increasing calls from many experts.

He later clarified his comments, saying that herd immunity was a natural consequence of the disease spreading - and that it was not the policy to allow Covid-19 to spread.