Researchers in Boston have detected long-lived antibodies in the saliva and the blood of coronavirus patients&nbsp;at least three months after symptom onset.

The study, published in the journal Science, points to the IgG class of antibodies as the longest-lasting antibodies detectable in the patients during this time frame and may serve as promising targets to detect and evaluate immune responses against the SARS-CoV-2 virus.

According to the researchers, including those from the Harvard Medical School in the US, these antibodies could be detected at similar levels in both blood and saliva, suggesting that saliva could be used as an alternative biofluid for antibody testing.

In the research, Anita Iyer and her team measured antibody responses in the blood of 343 patients with COVID-19 for up to 122 days after symptom onset, and compared these responses to those of 1,548 control individuals sampled before the pandemic.

The scientists focused only on antibodies specific to the receptor binding domain of the SARS-CoV-2 spike protein which it uses to enter host cells.

They estimated sensitivities of the antibody types IgG, IgA, and IgM at 95 per cent, 90 per cent and 81 per cent, respectively, for detecting infected individuals between 15 to 28 weeks after symptom onset.

Among these antibodies, the study noted that spike protein-specific IgM and IgA were short-lived, dropping beneath detection levels at around 49 and 71 days, respectively, after the appearance of symptoms.

However, it noted that the spike protein-targeted IgG responses decayed slowly over a period of 90 days, with only three individuals losing them within this timeframe.

According to the researchers, the levels of spike protein-specific IgG strongly correlated with levels of neutralising antibodies in the patients.

They also did not observe cross-reactivity of any SARS-CoV-2-targeting antibodies with other "common cold" coronaviruses.

Another study published in the journal Science also found that while IgA and IgM antibodies targeting the spike protein's receptor binding domain rapidly decayed, the IgG type remained relatively stable for up to 105 days after symptom onset in 402 patients with COVID-19.

In this study, researchers including Baweleta Isho from the University of Toronto in Canada, detected spike protein-specific antibodies in the saliva, as well as the blood, of these patients.

They charted the patients' antibody responses from three to 115 days after symptom onset, and compared their profiles with 339 pre-pandemic controls.

The scientists found that patients with COVID-19 showed peak IgG levels at 16 to 30 days after the appearance of symptoms.

According to the researchers, the levels of all spike protein-specific IgG, IgM, and IgA antibodies in the blood positively correlated with levels observed in matched saliva samples.

"Given that the virus can also be measured in saliva by PCR, using saliva as a biofluid for both virus and antibody measurements may have some diagnostic value," they wrote in the study.

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Researchers in Boston have detected long-lived antibodies in the saliva and the blood of coronavirus patients at least three months after symptom onset. The study, published in the journal Science, points to the IgG class of antibodies as the longest-lasting antibodies detectable in the patients during this time frame and may serve as promising targets to detect and evaluate immune responses against the SARS-CoV-2 virus.

Researchers in Boston have detected long-lived antibodies in the saliva and the blood of coronavirus patients at least three months after symptom onset. The study, published in the journal Science, points to the IgG class of antibodies as the longest-lasting antibodies detectable in the patients during this time frame and may serve as promising targets to detect and evaluate immune responses against the SARS-CoV-2 virus. According to the researchers, including those from the Harvard Medical School in the US, these antibodies could be detected at similar levels in both blood and saliva, suggesting that saliva could be used as an alternative biofluid for antibody testing. In the research, Anita Iyer and her team measured antibody responses in the blood of 343 patients with COVID-19 for up to 122 days after symptom onset, and compared these responses to those of 1,548 control individuals sampled before the pandemic. The scientists focused only on antibodies specific to the receptor binding domain of the SARS-CoV-2 spike protein which it uses to enter host cells. They estimated sensitivities of the antibody types IgG, IgA, and IgM at 95 per cent, 90 per cent and 81 per cent, respectively, for detecting infected individuals between 15 to 28 weeks after symptom onset. Among these antibodies, the study noted that spike protein-specific IgM and IgA were short-lived, dropping beneath detection levels at around 49 and 71 days, respectively, after the appearance of symptoms. However, it noted that the spike protein-targeted IgG responses decayed slowly over a period of 90 days, with only three individuals losing them within this timeframe. According to the researchers, the levels of spike protein-specific IgG strongly correlated with levels of neutralising antibodies in the patients. They also did not observe cross-reactivity of any SARS-CoV-2-targeting antibodies with other "common cold" coronaviruses. Another study published in the journal Science also found that while IgA and IgM antibodies targeting the spike protein's receptor binding domain rapidly decayed, the IgG type remained relatively stable for up to 105 days after symptom onset in 402 patients with COVID-19. In this study, researchers including Baweleta Isho from the University of Toronto in Canada, detected spike protein-specific antibodies in the saliva, as well as the blood, of these patients. They charted the patients' antibody responses from three to 115 days after symptom onset, and compared their profiles with 339 pre-pandemic controls. The scientists found that patients with COVID-19 showed peak IgG levels at 16 to 30 days after the appearance of symptoms. According to the researchers, the levels of all spike protein-specific IgG, IgM, and IgA antibodies in the blood positively correlated with levels observed in matched saliva samples. "Given that the virus can also be measured in saliva by PCR, using saliva as a biofluid for both virus and antibody measurements may have some diagnostic value," they wrote in the study.

Long-lived antibodies detected in saliva, blood of coronavirus patients

The UK is set to distribute millions of free coronavirus antibody tests after a version passed its first major trials.

The fingerprick tests can tell within 20 minutes if a person has ever been exposed to the coronavirus, and have been found to be 98.6% accurate in secret human trials held in June, the Daily Telegraph newspaper reported on Friday.

It added the test was developed by the UK Rapid Test Consortium (UK-RTC), a partnership between Oxford University and leading UK diagnostics firms.

<a href="https://www.wionews.com/world/australian-researchers-invent-20-minute-coronavirus-blood-test-313975">Also read | Australian researchers invent 20-minute coronavirus blood test</a>

Ttens of thousands of prototypes have already been manufactured in factories across the United Kingdom, and a regulatory approval is awaited.

Ministers are hoping that the AbC-19 lateral flow test will be available for use in a mass screening programme before the end of the year, the newspaper reported.

<a href="https://www.wionews.com/world/uk-approves-highly-accurate-covid-19-antibody-test-298651">Also read | UK approves 'highly accurate' COVID-19 antibody test</a>

The tests are likely to be free and would be ordered online instead of being sold in supermarkets, according to plans cited by the newspaper.

The UK is set to distribute millions of free coronavirus antibody tests after a version passed its first major trials. The fingerprick tests can tell within 20 minutes if a person has ever been exposed to the coronavirus, and have been found to be 98.

The UK is set to distribute millions of free coronavirus antibody tests after a version passed its first major trials. The fingerprick tests can tell within 20 minutes if a person has ever been exposed to the coronavirus, and have been found to be 98.6% accurate in secret human trials held in June, the Daily Telegraph newspaper reported on Friday. It added the test was developed by the UK Rapid Test Consortium (UK-RTC), a partnership between Oxford University and leading UK diagnostics firms. Also read | Australian researchers invent 20-minute coronavirus blood test Ttens of thousands of prototypes have already been manufactured in factories across the United Kingdom, and a regulatory approval is awaited. Ministers are hoping that the AbC-19 lateral flow test will be available for use in a mass screening programme before the end of the year, the newspaper reported. Also read | UK approves 'highly accurate' COVID-19 antibody test The tests are likely to be free and would be ordered online instead of being sold in supermarkets, according to plans cited by the newspaper.

Coronavirus antibody test passes first major trials in UK with 98.6% accuracy

Health officials in England have approved a test&nbsp;to find out whether people have been infected with coronavirus in the past.

Public Health England (PHE) said the antibody test, developed by Swiss pharmaceutical company Roche, was a "very positive development".

The blood test looks for antibodies to see if a person has already had the virus and might now have some immunity. However,&nbsp;officials have said such tests are not reliable enough until now.

Experts at the government's Porton Down facility evaluated the Roche test last week, Public Health England said, and found it to be "highly specific".

Health minister Edward Argar said the tests would mainly be used on those in the NHS and social care settings to begin with.&nbsp;

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"This is a very positive development because such a highly specific antibody test is a very reliable marker of past infection, said Professor John Newton, national co-ordinator of the UK Coronavirus Testing Programme.

"This in turn may indicate some immunity to future infection although the extent to which the presence of antibodies indicates immunity remains unclear," he said.

Health officials in England have approved a test to find out whether people have been infected with coronavirus in the past. Public Health England (PHE) said the antibody test, developed by Swiss pharmaceutical company Roche, was a "very positive development".

Health officials in England have approved a test to find out whether people have been infected with coronavirus in the past. Public Health England (PHE) said the antibody test, developed by Swiss pharmaceutical company Roche, was a "very positive development". The blood test looks for antibodies to see if a person has already had the virus and might now have some immunity. However, officials have said such tests are not reliable enough until now. Experts at the government's Porton Down facility evaluated the Roche test last week, Public Health England said, and found it to be "highly specific". Health minister Edward Argar said the tests would mainly be used on those in the NHS and social care settings to begin with. "This is a very positive development because such a highly specific antibody test is a very reliable marker of past infection, said Professor John Newton, national co-ordinator of the UK Coronavirus Testing Programme. "This in turn may indicate some immunity to future infection although the extent to which the presence of antibodies indicates immunity remains unclear," he said.

UK approves 'highly accurate' COVID-19 antibody test

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Long-lived antibodies detected in saliva, blood of coronavirus patients

Coronavirus antibody test passes first major trials in UK with 98.6% accuracy

UK approves 'highly accurate' COVID-19 antibody test