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Coronavirus immunity starts to fade away just weeks after people show symptoms, a new study by UK scientists showed.
King's College London research found that the presence of antibodies peaked three weeks after symptoms appeared, before fading away.
In some cases, the antibodies were undetectable three months afterward.
It followed a Spanish study last week that also showed antibody protection rapidly declining in many patients.
One of the UK study's authors said it put "another nail in the coffin of the dangerous concept of herd immunity."
Immunity to the coronavirus may disappear within months for many patients, according to a major new UK study which found that antibodies peaked three weeks after symptoms appeared, before gradually fading away.
For some patients, no antibodies were detected after just a few months, throwing doubt on hopes for a long-lasting vaccine.
The study, which was carried out by scientists at King's College London and first reported by The Guardian, "puts another nail in the coffin of the dangerous concept of herd immunity," one of its authors said.
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The study was based on the antibody responses of 90 patients and health workers at Guy's and St. Thomas' NHS Foundation Trust. It showed that 60% of those tested had "potent" antibodies while battling COVID-19, but just 17% had the same level of potency three months later.
The potency of the antibodies fell by as much as 23 times over the three months, the study found, and in some cases were undetectable at the end of that period of time.
The study, which has not yet been peer-reviewed, found that antibodies were more potent and lasted longer in patients with the most severe cases of the COVID-19 virus.
However, the findings suggest that like a common cold, the coronavirus can reinfect people, even if they developed antibodies during their first infection.
It is the latest study to pour cold water over so-called herd immunity — the theory that a population will become immune to the virus if at least 60% of people catch it.
A similar study in Spain, which was published last week, found that just 5% of people tested maintained coronavirus antibodies. Fourteen percent of people who tested positive for the antibodies in the first round of testing did not test positive in subsequent tests carried out weeks later.
Two of the Spanish study's authors, Isabella Eckerle and Benjamin Meyer, said: "In light of these findings, any proposed approach to achieve herd immunity through natural infection is not only highly unethical, but also unachievable."
Authors of the new UK report reached similar conclusions.
One of the UK study's authors, professor Stuart Neil, said the study showed any immunity generated "doesn't last very long."
"One thing we know about these coronaviruses is that people can get reinfected fairly often," he said. "What that must mean is that the protective immunity people generate doesn't last very long. It looks like Sars-Cov-2, the virus that causes Covid-19, might be falling into that pattern as well."
The study "puts another nail in the coffin of the dangerous concept of herd immunity," professor Jonathan Heeney, a virologist at the University of Cambridge, said, adding that deliberately trying to get infected in the name of herd immunity created the risk of severe health damage in the future.
"I cannot underscore how important it is that the public understands that getting infected by this virus is not a good thing. Some of the public, especially the youth, have become somewhat cavalier about getting infected, thinking that they would contribute to herd immunity," he said.
"Not only will they place themselves at risk, and others, by getting infected, and losing immunity, they may even put themselves at greater risk of more severe lung disease if they get infected again in the years to come," he added.
However, professor Arne Akbar, who is an immunologist at UCL, told The Guardian that T cells, which are produced to fight common colds, may help supplement the protection produced by antibodies, meaning that immunity may last longer than the study suggests.
The findings suggest one vaccine won't be enough
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Katie Doores of King's College London, the UK study's lead author, said the findings could be a sign that any future vaccine for the coronavirus would need to be provided regularly for people to maintain immunity.
"People are producing a reasonable antibody response to the virus, but it's waning over a short period of time and depending on how high your peak is, that determines how long the antibodies are staying around," she said.
"Infection tends to give you the best-case scenario for an antibody response, so if your infection is giving you antibody levels that wane in two to three months, the vaccine will potentially do the same thing," she added. "People may need boosting and one shot might not be sufficient."
In an interview with Sky News reported by The Guardian, professor Robin Shattock of Imperial College London said that while reinfection would probably be "less severe" because of people retaining "immune memory," the risk of them passing on the virus meant they would likely have to receive boosts of the vaccine on a regular basis.
"Ultimately this may require the use of annual boosting immunisations, particularly for the most vulnerable. This could be delivered alongside annual influenza immunisations," he said.
UK Prime Minister Boris Johnson's government has denied initially trying to pursue a strategy of herd immunity before it was warned that it would lead to the deaths of hundreds of thousands of people.
An Italian health minister last month said Johnson revealed his intention to pursue herd immunity in a phone call with Italian Prime Minister Giuseppe Conte on March 13, a little more than a week before the UK entered a countrywide lockdown.
On the same day, Patrick Vallance, the chief scientific adviser to the UK government, said he believed the UK would be able to achieve herd immunity.
Read the original article on Business Insider