Vaccinating every single person in the UK will not be enough to achieve herd immunity, a new study claims.
Analysis from the University of East Anglia (UEA) found the highly-virulent B.1.1.7 strain, which emerged in Kent in September, has made it impossible to ever achieve herd immunity with the current effectiveness of authorised vaccines.
The researcher say that even if every person in the UK, including children, gets the Oxford jab, this would only be enough to bring the R rate down to 1.325 when all restrictions are lifted.
However, the Oxford vaccine is only approved for over-18s and if all adults — 79 per cent of the UK — got this vaccine, the R rate would be 1.98, they add.
R is the number of people that one infected person will pass on the virus to, on average. When the R value is less than 1, it means the epidemic is shrinking and when it exceeds one, it is growing.
Pfizer’s jab is approved for everyone over 16 — 81 per cent of the UK. The study found 81.9 per cent of the UK population, more than every single person over 16, would need to be vaccinated in order to achieve herd immunity.
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Pictured, the impact on R rate for various vaccination scenarios, herd immunity is only achieved if R is kept below 1. The green line shows the Pfizer vaccine, and the blue line shows the effectiveness of Oxford’s vaccine according to the 70.4% effectiveness claimed in data sent to MHRA. The red line shows data from phase 3 clinical trials for two standards dose jabs of the Oxford jab against both symptomatic and asymptomatic infection
Analysis from the University of East Anglia (UEA) found the highly-virulent B.1.1.7 strain which evolved in Kent in September has made it impossible to ever achieve herd immunity with the current effectiveness of vaccines. Pictuured, Basil Henry, 84, is one of the first people to receive the Oxford/AstraZeneca vaccine at the opening of the first Pharmacy2U Covid-19 vaccination centre at the Odeon Cinema in Aylesbury
Researchers say that if every person in the UK, including children, gets the Oxford jab, this would only be enough to bring the R rate down to 1.325 when all restrictions are lifted. However, the Oxford vaccine is only approved for over-18s and if all adults — 79 per cent of the UK — got this vaccine, the R rate would be 1.98, they add. Pictured, members of the public attend a a temporary vaccination centre set up inside Salisbury Cathedral
‘The herd immunity threshold is the level of the population that needs to be immune to reduce R below 1 and therefore eliminate circulating virus,’ explains Professor Azra Ghani, Chair in Infectious Disease Epidemiology at Imperial College London, who was not involved with the study.
‘When the basic reproductive number (R0) is high, we need both high efficacy vaccines and a high uptake of vaccination across the population to achieve this threshold.’
The research from Professor Paul Hunter and Professor Alastair Grant looked at the impact of coronavirus spread following a vaccination drive and when all non-pharmaceutical interventions (NPIs), such as social distancing and mask wearing, have been lifted.
Three vaccines have been given regulatory approval in the UK, from Oxford/AstraZeneca, Moderna and BioNTech/Pfizer.
They have been found effective at stopping symptomatic infection and therefore preventing severe disease. But their effectiveness at completely neutralising the virus and stopping it replicating inside the body, known as sterilising immunity, remains unknown.
‘We don’t know if any of the vaccines provide sterilising immunity,’ Professor Hunter told MailOnline.
‘As far as we can tell, if you are to stop somebody spreading the infection, you need sterilising immunity.’
Sir Patrick Vallance said yesterday that at least 70 per cent of the population would need to be protected from the virus – either by vaccination or previous infection – in order to achieve herd immunity.
Currently, 4.6 million people in the UK have had at least one of their jabs, according to official NHS figures, and one in eight people have been infected already.
This leaves at least 39 million people who need to get the jab to reach the 70 per cent mark touted by Sir Patrick, the government’s Chief Scientific Advisor.
But the UEA study found this may only be true for the original strain of coronavirus, which has now been displaced by the more infectious Kent variant.
Data shows vaccinating 69 per cent of the population with Pfizer’s jab, which is 95 per cent effective, would be enough for herd immunity against the old strain. However, 93 per cent of the UK population would need to be vaccinated if receiving the Oxford jab.
But when accounting for the new variant, which the academics assume is 56 per cent more infectious, the equation changes dramatically.
‘Vaccinating the entire population with the Oxford vaccine would only reduce the R value to 1.325 while the Pfizer vaccine would require 82 per cent of the population to be vaccinated to control the spread of the new variant,’ the researchers write in their study, which has not yet been peer-reviewed but is available online a preprint.
Professor Grant says the Oxford vaccine reduces the likelihood of serious illness following infection, but is less effective at stopping asymptomatic infection.
In the study, the British researchers worked on the assumption the Oxford vaccine is 70.4 per cent effective against coronavirus infection, as this is the headline figure on the study data received by the MHRA which led to its approval last month.
However, this figure is based on the protection from severe disease, which leads to death.
But when accounting for asymptomatic infections, it is only 52.5 per cent effective, Professor Grant says.
Pictured, the Al Abbas Mosque in Birmingham, which is being used as a covid vaccination centre. The research from Professor Paul hunter and Professor Alastair Grant looked at the impact of coronavirus spread following a vaccination drive and when all non-pharmaceutical interventions (NPIs), such as social distancing and mask wearing, have been lifted
‘This means that its overall protection against infection is only partial – around 50 per cent.’
‘This combination of relatively low headline efficacy and limited effect on asymptomatic infections means that the Oxford vaccine can’t take us to herd immunity, even if the whole population is immunised.
‘Vaccinating 82 per cent of the population with the Pfizer vaccine would control the spread of the virus – but it isn’t licenced for use on under 16s, who make up 19 per cent of the population.
‘Also, some people will refuse the vaccine, so achieving an 82 per cent vaccination rate will likely be impossible.’
The academics recommend that healthcare workers who are highly exposed to the virus should receive the more effective mRNA-based Pfizer and Moderna vaccines and not the less effective Oxford vaccine.
‘The Oxford vaccine will no doubt be an important control intervention, but unless changes to the dose regime can increase its efficacy, it is unlikely to fully control the virus or take the UK population to herd immunity,’ Professor Grant adds.
‘If we cannot achieve herd immunity, vulnerable unvaccinated individuals will remain at risk.
‘We do need to consider how best to protect these individuals when social restrictions are eventually relaxed as the result of a successful vaccine roll out programme.’
Professor Hunter told MailOnline that getting the more effective mRNA jabs to healthcare workers should be of consideration for the Joint Committee on Vaccination and Immunisation (JCVI), which determines the vaccine priority list.
‘We also need to vaccinate every vulnerable person who needs to be vaccinated and we need to do more to fascinate people who don’t want vaccine and may be relying on herd immunity, as this is likely impossible.’
However, although they believe healthcare workers should get the Pfizer jab, they do not believe it should be prioritised for all vulnerable people, including those classed as clinically extremely vulnerable and all people over 70.
‘It is not necessary to give vulnerable people the Pfizer vaccine and not the Oxford one. I would be hard pushed to say the Oxford vaccine is any worse or better than other vaccines at preventing severe disease,’ Professor Hunter says.
The researchers included the Kent strain, which now accounts for at least 61 per cent of all UK infections, in their analysis, but did not have enough data to look at the impact of the South Africa variant.
Professor Hunter told MailOnline that getting the more effective mRNA jabs to healthcare workers should be of consideration for the Joint Committee on Vaccination and Immunisation (JCVI), which determines the vaccine priority list
‘The British variant does not seem to be an escape mutant as it is lacking the E484K gene,’ Professor Hunter says.
The E484K gene mutation is believed to make the virus adept at avoiding antibodies which have been made by the human immune system following prior infection.
As a result, it is to blame for numerous reinfection events and scientists are growing increasingly concerned it may be able to evade current vaccines.
‘The problem with english strain is it spreading more quickly,’Professor Hunter adds.
‘The South Africa strain is a different matter and has both the increased infection mutant and a degree of escape mutant.
‘This does not necessarily mean the vaccine is useless but is probably slightly less effective.’
Dr Jonathan Stoye from the Francis Crick Institute, who was not involved in the study, comments on the paper: ”It reaches the provocative conclusion that administration of the Adenovirus based vaccine from Oxford/AstraZeneca alone, despite a major reduction in the seriousness of COVID-19 disease, is unlikely to generate the herd immunity needed for complete control of virus spread.
‘Based on the data currently available, this study appears strong and the conclusion unarguable.
‘It points to a continuing role for non-pharmaceutical interventions such as the wearing of face masks and hand washing as well as suggesting a possible utility for booster vaccinations with RNA based delivery systems.’