BRITAIN will reach herd-immunity by July thanks to Covid vaccines ending deadly infection waves, scientists have predicted.
More than 10 million have now received their first dose of the jab – marking a huge mile stone in the UK’s fight against the deadly virus.
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And reports suggest that all adult Brits are on track to receive both Covid jabs by August this year.
Now experts modelling the pandemic claim that the country will have reached population immunity before that point.
Scientists at University College London have released a dashboard to track the effectiveness of the vaccination roll out – and provide some long-term forecasts of the coronavirus outbreak.
Their long-term forecast suggests that herd-immunity – or the indirect protection to Covid among the population – will be reached by mid-July.
The modelling was led by Professor Karl Friston, who is also scientific director at the Wellcome Centre for Human Neuroimaging.
He said: “Vaccination appears to be having a tangible effect on confirmed new cases and daily death rates recorded over the past few weeks.
“If the vaccination programme continues to unfold at its current pace – and lockdown is eased gradually as a function of declining prevalence – we might attain herd immunity by as early as July.
If the vaccination programme continues to unfold at its current pace we might attain herd immunity by as early as July
Professor Karl Friston
“This encouraging, perhaps optimistic, forecast accommodates fluctuations in viral transmissibility.
“However, there is a lot of uncertainty about transmission risk that should nuance any interpretation of these predictions.”
He added: “These long-term predictions reflect a material response to the third lockdown that is clearly evident in declining incidence, hospital admissions and daily death rates.
“At present, the reproduction ratio is estimated to be the lowest it has been since late April but is likely to rise gently again as restrictions are eased over the forthcoming months.”
FLUCTUATIONS
To determine a herd immunity threshold – or the percentage of the population that needs to become immune to Covid so that someone without immunity is unlikely to become infected – they turned to the effective reproduction ratio under pre-pandemic contact rates.
Their modelling shows that it fluctuates over time, which reflects the fact that transmission risk changes with time.
This can be down to viral evolution, such as mutations, and seasonal variations such as the temperature and socialising outdoors.
The scientists say: “The current estimates of the herd immunity threshold show that it has risen substantially since last July and is predicted to fall again during the spring.
“Clearly, there is a substantial amount of uncertainty about these long-term forecasts – as indicated by the wide credible intervals.
“Part of this uncertainty reflects uncertainty about the age-specific rollout of vaccinations.”
The World Health Organisation (WHO) says that to safely achieve herd immunity against Covid-19, a substantial proportion of a population would need to be vaccinated.
This would lower the overall amount of virus able to spread in the whole population.
ON TARGET
Britain’s vaccination rollout is among one of the fastest in the world, with more than 10 million people already receiving their first dose.
The NHS is currently working through the top four priority groups most vulnerable to Covid, including the elderly and frontline healthcare staff.
According to the latest data, from the week ending January 24, almost 90 per cent of those aged 75 and over have received their first jab.
Britain is now on target to jab the most vulnerable groups, including all those over 70, within the next 11 days.
But the vaccines minister has declined to put a date on when all over-50s can expect to receive a Covid-19 jab.
Nadhim Zahawi said a target would be set for reaching all those aged 50 to 70, as well as those with underlying conditions which put them at higher risk of serious disease, once the most vulnerable have been offered a jab by February 15.
Previously, NHS England chief executive Sir Simon Stevens has said the aim is for all over-50s and those at risk to be vaccinated by the end of April.
The jab priority list is determined by the independent Joint Committee on Vaccination and Immunisation’s (JCVI).
Phase 1 is made up of groups one to nine, which in addition those already invited for a jab includes all those over 50 and everyone over 16s with underlying health conditions with higher risk of severe disease or death.
These top priority four groups alone account for 88 per cent of Covid deaths.
It is estimated that taken together, including groups one to nine represents around 99 per cent of preventable deaths from Covid-19.
HERD IMMUNITY THROUGH VACCINES
The WHO has said it supports achieving herd-immunity through vaccination and not by allowing a disease to spread.
This they warn would result in unnecessary cases and deaths.
It came after Sweden made attempts to achieve natural herd immunity by avoiding lockdowns – a plan that later backfired when cases surged out of control in December.
Speaking to the media in October last year, WHO director-general Tedros Adhanom said: “Herd immunity is a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached.
“For example, herd immunity against measles requires about 95 per cent of a population to be vaccinated.
Herd immunity is achieved by protecting people from a virus, not by exposing them to it
Tedros Adhanom
“The remaining five per cent will be protected by the fact that measles will not spread among those who are vaccinated. For polio, the threshold is about 80 per cent.
“In other words, herd immunity is achieved by protecting people from a virus, not by exposing them to it.
“Never in the history of public health has herd immunity been used as a strategy for responding to an outbreak, let alone a pandemic. It is scientifically and ethically problematic.”
But even once the UK has reached herd immunity, ministers warn that Brits won’t be safe from Covid until the rest of the world also has protection.
Mr Zahawi today said “no one is really safe until the whole world is safe”.
The vaccine minister told MPs that he was “pleased” by the news about the effectiveness of the Oxford/AstraZeneca vaccine, adding: “This is, of course, really great news for us all.
“But we will not rest on our laurels – no one is really safe until the whole world is safe.
“Our scientific pioneers will keep innovating so we can help the whole world in our collective fight against this virus.”
Data from a study by the University of Oxford released this week suggested a single dose of the Oxford/AstraZeneca vaccine offers protection of 76 per cent for up to three months and may reduce transmission by 67 per cent – with efficacy rising to 82.4 per cent after the second dose 12 weeks later.
