HERD immunity levels against coronavirus in the UK may exceed people’s expectations and prevent a second wave, researchers hope.
While super-spreaders infect many, it appears some people are effectively super-blockers and enjoy natural resistance to the killer bug, say Oxford University boffins.
The scientists have written about “host resistance” to the new virus and a possibly lower threshold of herd immunity needed to fend off further devastating Covid-19 outbreaks.
Their paper, published on Medrxiv, says that it is widely believed the threshold needed to enjoy herd immunity against the new disease is more than 50 per cent.
But, its research suggests that if just 20 per cent of the UK’s population has in-built resistance to Covid-19, a second wave is not inevitable.
Herd immunity refers to where enough people in a population have immunity to an infection to be able to effectively stop that disease from spreading.
For herd immunity, it doesn’t matter whether the protection comes from vaccination, or from people having had the disease. The crucial thing is that they are immune.
The Oxford Uni study suggests the epidemiological limit to reach herd immunity “may be greatly reduced if a fraction of the population is unable to transmit the virus”.
This is feasible, they add, if people have inbuilt “resistance or cross-protection from exposure to seasonal coronaviruses”.
The report says: “Significant reductions in expected mortality can also be seen in settings where a fraction of the population is resistant to infection.”
Results “suggest that sufficient herd-immunity may already be in place to substantially mitigate a potential second wave”, the researchers add.
“It has been evident from the outset that the risk of severe disease and death from Covid-19 is not uniformly distributed across all age classes.
“The bulk of deaths among the over 12 million cases reported worldwide are occurring among older age classes and those with [pre-existing conditions].
“It is further becoming clear that risk of infection is also not uniformly distributed across the population,” the reports says.
Scientists at Oxford point to those managing to fend off the virus as having “high functioning immunity”.
And, if antibodies to the disease are built up in “10-20 per cent” of the population, “this is entirely compatible with local levels of immunity having approached or even exceeded the herd immunity threshold.
“In which case the risk and scale of resurgence is lower than currently perceived,” say the researchers.
Immunity to the bug has been hitting headlines for months, with King’s College research saying antibody responses to the killer bug “can be detected in most infected individuals 10-15 days following the onset of Covid-19 symptoms”.
It investigated samples from 65 coronavirus patients, 94 days after they had been diagnosed with Covid-19.
Worryingly, King’s College’s study found that immunity to fight coronavirus might disappear only three months after infection.
