Immunity against Covid-19 may not last very long, according to the latest research from Imperial College London.
This means that people who have had the virus and now think they are safe may still be putting themselves and others at risk. It also means protective measures, such as social distancing and wearing masks, still need to be kept in place.
The REACT-2 project, which focuses on infection numbers through antibody tests, found a fall of 26% in the numbers of people testing positive for antibodies after only three months since its first round of tests.
Antibodies are part of what help our immune system defend against viruses and this quite rapid fall in the levels of protection sends worrying signals.
Not least, it means there’s a risk we could catch Covid-19 several times.
It also means that lockdowns may be the only way to control the levels of infection. The so-called herd immunity – when a large portion of a community becomes immune to a disease, making the spread of disease from person to person less likely – is no longer viable.
The study suggests that people could become reinfected with Covid-19 in the same way they can catch the common cold, which is a related coronavirus, every six to 12 months.
Cases of Covid-19 reinfection are still fairly rare and there’s not enough data to assess the situation accurately, so our immune system may still have a key role to play. There are other parts of it, such as our T-cells, that may kick in and provide hope, but a way to test these has not been developed yet.
What does this new evidence mean for the development of a vaccine? The researchers say it’s still important, as a vaccine might provide better protection than the infection itself.
“The big picture is after the first wave, the great majority of the country [the UK] didn't have evidence of protective immunity,” one of the researchers, Professor Graham Cooke tells BBC. “The need for a vaccine is still very large, the data doesn't change that.”
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