UK COVID Vaccination
The total percentages of the UK population who had received the SARS-CoV-2 vaccine by 11th Sep 2022 are First Dose: 79.13%, Second Dose: 74.65%, Third Dose: 0%. The graphs below show both cumulative and daily, how many people received the first dose and second dose of a SARS-CoV-2 vaccine in the UK on the date shown.
Number Receiving Vaccine By Date Published
UK COVID Immunity
With access to the number of people receiving the a COVID19 vaccine in the UK, the number of people with neutralising antibodies from SARS-CoV-2 (i.e., those previously infected with SARS-CoV-2), and likely percentage efficacy of vaccine used, we can make an approximate running estimate of percentage of people in the UK likely to have SARS-CoV-2 immunity.
Data taken from the UK infection survey shows that in December 2020, which was when the UK vaccination programme began, 11.6% of the UK population (population estimate for 2020 used = 68,004,973) had SARS-CoV-2 antibodies in their blood. To give a conservative estimate, if we assume that only 85% of those vaccinated will gain immunity (based on findings from the COVID Symptom Study team team), then adding 85% of the total vaccinated in the UK to the initial 11.6% with SARS-CoV-2 antibodies, gives the rolling data graph below.
We can use this graph to see how close we are as a nation to the immunity levels required for herd protection. Depending on the Basic Reproduction Number (R0), a crude herd immunity percentage level requirement can be calculated using the equation (1-[1/R0])x100.
For R0 = 2, herd protection requires 50% of the UK population to be immune. For R0 = 3, 67% immunity is required, and for R0 = 4.6, which is an upper estimate of the Basic Reproduction Number published in the BMJ (www.bmj.com/content/369/bmj.m1891), 78% immunity is required.
As new strains emerge, with higher transmitability to previous strains, and become dominant in the UK, then their basic reproduction number (R0) increases. This effects the required herd immunity threshold to stop SARS-CoV-2 spreading exponentially. For the B.1.617.2 (delta) strain, R0 is estimated at 6.0. For this strain, 83.3% of the population require immunity to establish herd protection. This means if a vaccine is 85% efficacious, then 98% of the population will need to be vaccinated.
In reality innate immunity already in the population for a number of reasons, including previous infection, will reduce the number of people needing vaccination to bring the on-going pandemic under control. The take home message here though, is that without a very high uptake of vaccine by the UK population, then the UK arm of the global SARS-CoV-2 pandemic, will never end.