People who have recovered from coronavirus may lose their immunity to the disease within six months, according to new research.
It could reinfect people year after year - just like the common cold, warn scientists. An analysis of patients with four similar coronaviruses found re-infection occurred frequently.
On average this started about a year after the initial bout - but happened up to twice as fast as this. One patient was struck down by the illness 17 times - around once every two years.
Corresponding author Dr Lia van der Hoek, of Amsterdam University Medical Centres, said: "The duration of protective immunity against Covid-19 may be short-lived." She added: "Caution may be needed when relying on policies that require long-term