There was widespread alarmist media coverage in July and again in October of research by Kings College and Imperial College respectively of research showing anti-body reaction to covid19 disappeared within as short as time as a few weeks (average 2-3 months).
Both researchers obliged media by saying the results showed that controversial ‘herd immunity’ concept could not work.
But a new study by University of Birmingham and Public Health England, shows memory T-cells were present in all 100 asymptomatic non-hospitalised patients they tested, meaning coronavirus patients have cellular immunity for at least six months after infection even when antibodies are undetectable.
It suggests that more people may have had Covid than previously thought but have lost their antibody response, meaning it would not show up in surveillance testing.
Previous studies have shown that Sars – a very similar virus to coronavirus – can induce a T-cell response that lasts 10 years, but it was unknown whether a cellular response also happened in Covid.
Dr Shamez Ladhani, consultant epidemiologist at PHE and the study’s author, said: “Cellular immunity is a complex but potentially very significant piece of the Covid-19 puzzle.
“Early results show that T-cell responses may outlast the initial antibody response, which could have a significant impact on Covid vaccine development and immunity research.”
Professor Paul Moss, the UK Coronavirus Immunology Consortium lead, of the University of Birmingham, said it was the first study in the world “to show robust cellular immunity remains at six months after infection in individuals who experienced either mild/moderate or asymptomatic Covid-19. Six months is an early time point, and cells can live for a very long time.”