Antibodies to the coronavirus drop after infection, the study says


Commuters wearing a mask or cover due to the COVID-19 pandemic walk past a London Underground tube train at Victoria Station during the evening ‘rus hour’ in central London on 23 September 2020.

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LONDON – Coronavirus antibodies drop as people recover from the disease, according to findings from a major UK study, potentially dealing a severe blow to those pushing for so-called herd immunity.

Researchers from Imperial College London surveyed 365,000 people in England in three rounds of testing between June 20 and September 28.

Analysis of finger-prick tests carried out at home found that rather than people who develop immunity over time, the number of people with antibodies capable of fighting Covid-19 has decreased by about 26% during the study period.

The REACT-2 study, which has not yet been peer-reviewed, found that 6% of those tested had antibodies to the virus when UK blocking measures were eased over the summer. However, at the start of the second wave of cases last month, this figure had dropped to 4.4%.

“This very large study showed that the percentage of people with detectable antibodies is decreasing over time,” said Helen Ward, one of the study authors and a professor at Imperial College London.

“We don’t know yet if this will leave these people at risk of reinfection with the virus that causes COVID-19, but it is essential that everyone continue to follow the lead to reduce the risk for themselves and others.”

What does this mean for herd immunity?

The findings suggest there may be a drop in the population’s immunity level in the months following the first wave of the coronavirus outbreak, potentially frustrating the hopes of those calling for a controversial herd immunity response strategy.

Herd immunity occurs when a sufficient population is immune to a disease, making it unlikely to spread and protect the rest of the community, according to the Mayo Clinic. It can be obtained through natural infection – when enough people are exposed to the disease and develop antibodies against it – and through vaccinations.

Health experts estimate that around 70% of the population would need to be vaccinated or have natural antibodies to achieve herd immunity.

A man wearing a protective mask, shelters from the rain under an umbrella as he walks past Chancery Lane tube station in London on October 21, 2020, as the government considers further lockdown measures to combat the rise in new coronavirus cases COVID-19.

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Some epidemiologists have suggested that targeting herd immunity would be a better response to the pandemic than lockdown measures. Many others, however, have sharply criticized a strategy that could require vulnerable people to protect themselves at home as the virus spreads among young and healthy people.

Earlier this month, Dr Anthony Fauci, the foremost expert on infectious diseases in the United States, described calls to let the virus tear apart the US population out of control as “nonsense” and “dangerous”.

To date, more than 43.5 million people around the world have contracted the coronavirus, with 1.16 million related deaths, according to data collected by Johns Hopkins University.

Implications for reinfection

The results of the REACT-2 study showed a downward trend in antibodies in people of all ages and in all areas of the UK, but not in healthcare professionals. The decline was greatest for people aged 75 and over, the study says, while the smallest decline was among those aged 18 to 24.

Researchers found that the decline in prevalent antibodies can be rapid initially, before the plateau. They warned that data on this was just starting to emerge.

The study only measured antibodies. The authors stated that it was not possible to determine whether the loss of antibody positivity would be related to an increased risk of an individual’s reinfection as it was unclear what contribution T cell immunity and memory responses played in immunity. protective during re-exposure.

T cells are part of the immune system that defends against specific foreign pathogens.

Late night drinkers after 10pm in Soho, London, after Prime Minister Boris Johnson announced that pubs and restaurants will be subject to a 10pm curfew from Thursday to fight the rise in coronavirus cases in England.

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“Our study shows that over time there is a reduction in the percentage of people who test positive for antibodies,” said Professor Paul Elliott, director of the Real Time Assessment of Community Transmission program at Imperial, and one of the authors of the study.

“The positive test for antibodies does not mean that you are immune to COVID-19. It is not clear what level of immunity the antibodies provide or how long this immunity lasts,” he continued.

“If someone tests positive for antibodies, they should still follow national guidelines including social distancing measures, undergo a swab test if they have symptoms, and wear face covers where required.”

– CNBC’s Noah Higgins-Dunn contributed to this report.


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