Immunity to norovirus lasts at least eight months, new data shows - and it suggests that survivors could be protected for years.
Researchers at La Jolla Institute in California found that levels of immune cells to COVID-19 slowly start to decline in the months following infection but sufficient amounts linger to block re-infection - perhaps for years.
It's a welcome shift from a large pool of studies that have suggested that antibodies fade within three months.
And it could mean that protection conferred by COVID-19 vaccines made by Pfizer and Moderna, which are both more than 90 percent effective at preventing infection, according to early data will last longer than previously thought - although neither company has had a chance to prove that, yet.
In recent months, the focus of coronavirus immunity research has shifted away from looking solely at antibodies - bespoke immune cell that develop in response to a new infection - to a wider array of immune agents in the body.
Immunity to coronavirus likely lasts at least eight months, and potentially years, suggests a new study preprint that looked at multiple types of immune cells including those that store the 'memory' of the virus and how to fight it. Pictured: German scientists' reimagining of the virus
The new study, posted ahead of peer review as a preprint on medRxiv, falls into this camp.
La Jolla researchers took periodic measurements of the levels of antibodies as well as memory T and B cells and other immune cells in the body.
These 'memory' cells are crucial.
Antibodies come in several types, the first of which appears within a day or two of infection, the second of which usually starts to ramp up over the course of one to three weeks following infection.
They also decline after that period.
But that doesn't mean that the body forgets how to make more of them.
The 'memory' blueprint is stored in B cells and T cells.
B cells become specialized factories to pump out antibodies.