COVID-19: Antibodies 'Remain for at Least 6 Months'

Peter Russell

February 03, 2021

A study has found that 99% of people who tested positive for SARS-CoV-2 retained antibodies to the virus for 3 months after infection.

Researchers at UK Biobank found that 87.8% remained seropositive for the full 6 months that the study lasted.

The discovery indicated that the antibodies produced following natural infection may provide a degree of protection for most people, scientists said.

Sir Patrick Vallance, the Government's chief scientific adviser, described the results as "useful confirmation of the maintenance of antibodies".

The latest findings were broadly in accord with interim results last month from the Sarscov2 Immunity & REinfection EvaluatioN (SIREN) study that suggested antibodies from people who had recovered from COVID-19 gave at least 83% protection against reinfection compared with people who had not had the disease before.

Naomi Allen, chief scientist for UK Biobank and professor of epidemiology at the University of Oxford, told a briefing hosted by the Science Media Centre: "When you take our findings that antibody levels seem to persist for at least 6 months, together with findings from other studies that show that the likelihood of reinfection following a natural infection is fairly low over the same period of time, it does suggest that people may be protected against subsequent infection for at least 6 months following a first infection with the virus."

Uncertainties Remain

The researchers said important questions remained. "We can't be sure that this provides a complete protection," said Professor Sir Rory Collins, UK Biobank principal investigator.

Sir Rory, who is professor of medicine and epidemiology at the University of Oxford, added: "And we still don't know either with the vaccines, or indeed with people who have been infected, whether they can still be transmitters and put others at risk."

Researchers said they had not had the opportunity to assess antibody levels over time in individuals who had received a COVID-19 vaccine compared to those naturally infected. However, the data was "encouraging".

"Whether the punch is bigger or smaller I'm not sure, but you clearly get a very good punch with both," Sir Rory told the briefing.

Scientists said they were not able to comment on antibody persistence from new variants of the SARS-CoV-2 virus because these were not widespread when their research concluded.

Biomedical Database

The UK Biobank study involved monthly blood samples and data on potential symptoms from 20,200 participants and their adult children and grandchildren.

Results showed that:

  • The proportion of the population with seroprevalence to SARS-CoV-2 increased from 6.6% in May/June 2020 to 8.8% by November/December 2020

  • Seroprevalence was most common in London (12.4%) and least common in Scotland (5.5%)

  • There was no difference in seroprevalence by gender, but the proportion of participants with detectable antibodies was higher in younger people (13.5% among those under 30) and lowest in elderly people (6.7% among those over 70)

  • Seroprevalence of SARS-CoV-2 was highest among participants of Black ethnicity (16.3%) and lowest among those of White (8.5%) and Chinese ethnicities (7.5%)

  • The most common symptom associated with having antibodies to SARS-CoV-2 was a loss of sense of taste and smell, which was reported by 43% of sero-positive participants

  • 24% of sero-positive participants were completely asymptomatic and 40% did not have one of the three 'classic' COVID-19 symptoms (fever, persistent dry cough, or loss of sense of taste or smell)

Lord Bethell, England's health minister, said: "While the findings offer some promise, now is not the time for complacency. We still do not fully understand how long protection from antibodies may last, and we know people with antibodies may still be able to pass the virus on to others.

"Right now, it remains vital for everyone to stay at home, even if you have had COVID-19 in the past, so we can stop the spread of the virus, protect the NHS and save lives."


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