(Bloomberg) -- People who catch Covid-19 twice tend to have a lower viral load the second time around, which may mean that they experience a milder illness, U.K. government figures show.

The Office for National Statistics said an analysis of test results from April 26 to July 17 found that so-called cycle threshold values were “significantly lower” in the first episode of illness. The lower the value, the higher the viral load and the stronger the positive test.

The risk of re-infection was low, particularly for those who had a strong positive test to begin with, according to the figures. The estimated rate of reinfection with a strong positive test was 3.1 per 100,000 participant days at risk, compared with 12.8 overall.

Many are still reporting having no symptoms at the time their test was done. Only 61% of those with a strong positive test reported symptoms in July, according to the ONS.

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