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No evidence recovered covid patients can’t be re-infected World Health Organisation says

The World Health Organization (WHO) said on Saturday that there was currently ‘no evidence’ that people who have recovered from COVID-19 and have antibodies are protected from a second coronavirus infection.

In a statement, the United Nations agency warned against issuing ‘immunity passports’ or ‘risk-free certificates’ to people who have been infected, saying the practice may actually increase the risk of spread as they may ignore standard advice.  

Until now the antibody tests had been considered the key to letting countries out of lockdown, allowing officials to get a clearer picture of the true size of the coronavirus outbreak. 

A healthcare worker performs a coronavirus antibody test at a SOMOS Community Care COVID-19 antibody walk-in testing site, Brooklyn, New York City, U.S., April 24, 2020

A healthcare worker performs a coronavirus antibody test at a SOMOS Community Care COVID-19 antibody walk-in testing site, Brooklyn, New York City, U.S., April 24, 2020

A healthcare worker performs a coronavirus antibody test at a SOMOS Community Care COVID-19 antibody walk-in testing site, Brooklyn, New York City, U.S., April 24, 2020

Chile said last week it would begin handing out ‘health passports’ to people deemed to have recovered from the illness. Once screened to determine if they have developed antibodies to make them immune to the virus, they could immediately rejoin the workforce. 

Italy has screened the blood of 20,000 people a day using the test, while one programme in the US planned to screen 40,000 healthcare workers.

Germany had begun to test 15,000 people, with plans to apply the findings to its whole population, and even Andorra has ordered 150,000 kits – enough to give its entire population two each.

The UK has carried out fewer than 5,000 antibody tests so far – despite mass schemes being carried out across the globe.     

The blood sample is taken using a finger prick

The blood sample is taken using a finger prick

A staff member at the Stanford Radiology department takes a blood sample from a teenager

A staff member at the Stanford Radiology department takes a blood sample from a teenager

 In early April, 2,500 volunteers took part in a Stanford University antibody study (pictured)

While the US Centers for Disease Control (CDC) set to work analysing blood donations of Washington and New York City residents – two of the worst-hit regions in the States, in the hopes it would offer a picture how how many people could be ‘immune’. 

Researchers hoping to establish whether herd immunity was a possibility estimated that as many as 442,000 people throughout the U.S, with a population of nearly eight million adults, had the virus as of April 9 – 55 times than confirmed positive cases at the time – 7,994.    

Against the wishes of the Trump administration, Larry Hogan, Maryland state’s Republican governor, said he had obtained 500,000 tests worth $9 million from South Korea’s LabGenomics following weeks of negotiations, with no assistance from U.S. fereral government.   

According to the WHO’s latest advice the data gathered may now only be useful for judging the ‘symptomatic’ proportion of the population, as results can’t be relied on to send people back to work.

A medical personnel shows a rapid antibody test kit for COVID-19, at a school converted into a mass testing facility on April 24, 2020 in Manila, Philippines

A medical personnel shows a rapid antibody test kit for COVID-19, at a school converted into a mass testing facility on April 24, 2020 in Manila, Philippines

A medical personnel shows a rapid antibody test kit for COVID-19, at a school converted into a mass testing facility on April 24, 2020 in Manila, Philippines

Coronavirus antibody testing in Oss, The Netherlands. The National Institute for Public Health and the Environment (RIVM) said it would begin testing 10,000 samples weekly on March 19

Coronavirus antibody testing in Oss, The Netherlands. The National Institute for Public Health and the Environment (RIVM) said it would begin testing 10,000 samples weekly on March 19

Coronavirus antibody testing in Oss, The Netherlands. The National Institute for Public Health and the Environment (RIVM) said it would begin testing 10,000 samples weekly on March 19

Antibodies are proteins in the blood which reveal if someone has already fought off an infection, including the deadly coronavirus.

An antibody test looks for these proteins in the blood whereas a molecular or diagnostic test, most widely used across the globe today, looks for the virus itself as an active infection in someone’s system.

A statement from the World Health Organisation explained that while most people appear to have produced antibodies to the Covid-19 virus in their recovery, it is not known if the presence of these antibodies in the blood is enough to stop a second infection.

WHY IS IT DIFFICULT FOR SCIENTISTS TO MAKE AN ANTIBODY TEST SPECIFIC FOR SARS-COV-2? 

Coronaviruses invade cells through so-called ‘spike’ proteins, but those proteins take on different shapes in different coronaviruses. 

The University of Texas at Austin were able to map the spike proteins of SARS-CoV-2 in mid February – a breakthrough for developing a vaccine.

It was also a huge step forward for scientists developing an antibody test.

There are questions about which antigens (proteins) are best for an antibody test target, ‘although the viral spike protein is universally perceived as the obvious candidate’, Anna Petherick, a lecturer in public policy at University of Oxford, wrote in The Lancet.

Which part of the spike protein to use is less obvious, and is causing difficulty in creating a reliable antibody test.

‘There is a lot hanging on the uniqueness of the spike protein,’ Ms Petherick said.

‘The more unique it is, the lower the odds of crossreactivity with other coronaviruses— false positives resulting from immunity to other coronaviruses. 

‘The most similar of these is severe acute respiratory syndrome coronavirus (SARS-CoV), which led to the SARS outbreak of 2002.

‘But another four coronaviruses cause the common cold, and ensuring there is no cross-reactivity to these is essential. ‘

A team at New York’s Icahn School of Medicine at Mount Sinai (NY, USA), has published details of antibody tests that use either the whole spike protein.

Others, such as Peng Zho at the Wuhan Institute of Virology in China, who was part of the team that sequenced SARS-CoV-2’s genetic code, have used the nucleocapsid protein and the spike protein.

‘[The] nucleocapsid protein is the most abundant viral protein, which means it’s easy to detect. But we also chose spike protein because it’s very specific,’ Dr Zho said. ‘Actually, for coronavirus, the most divergent protein is [the] spike protein.’

The World Health Organisation said: ‘WHO continues to review the evidence on antibody responses to SARS-CoV-2 infection. Most of these studies show that people who have recovered from infection have antibodies to the virus. 

‘However, some of these people have very low levels of neutralizing antibodies in their blood, suggesting that cellular immunity may also be critical for recovery.

‘As of 24 April 2020, no study has evaluated whether the presence of antibodies to SARS-CoV-2 confers immunity to subsequent infection by this virus in humans.’ 

The organisation also notes that the antibody tests may ‘falsely catagorize people in two ways’, labelling people who have been infected as negative and those who have not as positive – leading to potentially deadly results.

Adding: ‘At this point in the pandemic, there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an ‘immunity passport’ or ‘risk-free certificate.’

‘People who assume that they are immune to a second infection because they have received a positive test result may ignore public health advice.

The news comes as Former Chancellor Philip Hammond today urged Britons to face the ‘reality’ that the UK must get back to work while people are still suffering with Covid-19.

The news comes as Former Chancellor Philip Hammond today urged Britons to face the ‘reality’ that the UK must get back to work while people are still suffering with Covid-19.

He told the Government to publish an exit plan outlining a strategy to ease the coronavirus lockdown and restart the economy.

Mr Hammond said the country could not afford to wait until a vaccine had become available before resuming more normal economic activity.  

Sweden, who has not enforced a full scale lockdown and is relying in part on herd immunity and the effectiveness of antibodies in those that have already had the virus, has seen a recent surge in cases and deaths due to coronavirus.

Sweden posted a record 812 new Covid-19 cases yesterday, adding 61 to the record 751 tally it reached the day before – with an additional 131 new deaths, leaping from 84 on Thursday. 

 

People have lunch outdoors at a restaurant in Stockholm, Sweden, on Wednesday, in a country which has not imposed a draconian lockdown

People have lunch outdoors at a restaurant in Stockholm, Sweden, on Wednesday, in a country which has not imposed a draconian lockdown

People have lunch outdoors at a restaurant in Stockholm, Sweden, on Wednesday, in a country which has not imposed a draconian lockdown 

This graph compares the infection rates in the UK and Sweden, with the world figure shown for comparison. The UK's rate has been consistently worse than Sweden's since March 28, five days after Boris Johnson announced a lockdown

This graph compares the infection rates in the UK and Sweden, with the world figure shown for comparison. The UK's rate has been consistently worse than Sweden's since March 28, five days after Boris Johnson announced a lockdown

This graph compares the infection rates in the UK and Sweden, with the world figure shown for comparison. The UK’s rate has been consistently worse than Sweden’s since March 28, five days after Boris Johnson announced a lockdown

Former chancellor Philip Hammond who has called on ministers to set out plans to begin easing the coronavirus lockdown and re-start the economy

Former chancellor Philip Hammond who has called on ministers to set out plans to begin easing the coronavirus lockdown and re-start the economy

Former chancellor Philip Hammond who has called on ministers to set out plans to begin easing the coronavirus lockdown and re-start the economy

On Thursday the UK’s Health Secretary Matt Hancock spoke about the goverment’s plans to administer antibody tests to a selection of the population, in a similar approach to Germany. 

Hancock said: ‘Understanding more about the rate of COVID-19 infection in the general population, and the longer-term prevalence of antibodies, is a vital part of our ongoing response to this virus.

‘This survey will help to track the current extent of transmission and infection in the UK, while also answering crucial questions about immunity as we continue to build up our understanding of this new virus.

Sweden's top disease expert Anders Tegnell (pictured in Stockholm last week) said that a full-scale lockdown may not have prevented care home deaths

Sweden's top disease expert Anders Tegnell (pictured in Stockholm last week) said that a full-scale lockdown may not have prevented care home deaths

Sweden’s top disease expert Anders Tegnell (pictured in Stockholm last week) said that a full-scale lockdown may not have prevented care home deaths 

‘Together, these results will help us better understand the spread of the virus to date, predict the future trajectory and inform future action we take, including crucially the development of ground-breaking new tests and treatments.’

UK Business Secretary Alok Sharma has been tasked with devising a strategy for each sector of the economy to get people back to work without putting public health at risk. 

The government is next legally obliged to review the lockdown restrictions on May 7.     

Speaking to BBC Radio 4 state epidemiologist Anders Tegnell said Sweden might withstand a ‘second wave’ better than other countries because its light-touch measures could be kept in place for longer than the draconian lockdowns elsewhere.

Sweden’s cases have been rising more slowly than Britain’s, but it has far more infections and deaths than the rest of Scandinavia.

Asked whether a lockdown would have prevented those deaths, Tegnell said it was a ‘very difficult question to answer at this stage’.

‘At least 50 per cent of our death toll is within elderly homes and we have a hard time to understand how a lockdown would stop the introduction of disease’, he said.

‘We already had a law making it illegal for visitors to come to elderly homes. They need constant care, they need a lot of people coming and going to take care of them.

‘So it’s a bit unclear to us if a lockdown really would have stopped this from happening or not.

‘It’s a difficult question and I don’t think we have the answer and I’m not sure we’ll ever get the answer completely.’

Saying that Sweden had passed the peak of the epidemic a week ago, Tegnell said as many as 20 per cent of Stockholm residents may already have had the virus.

‘We believe that we have an immunity level, if I remember rightly, somewhere between 15-20 per cent of the population in Stockholm,’ he said.

‘[This is] not complete herd immunity but it will definitely affect the reproduction rate and slow down the spread.’

 

  

 

 

 

Courtesy DAILY MAIL

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