Being fully vaccinated against Covid-19 cuts the risk of long Covid in half in the small proportion of people who get a breakthrough infection, a detailed analysis of UK data shows.
Analysis of more than 1.2 million users of the ZOE Covid Symptom Study App who had one vaccine dose showed 0.5% (6,030) subsequently tested positive for Covid-19.
The study of people who had been vaccinated between December 2020 and July 2021 also found that just 0.2% (2,370) of 971,504 who had been double jabbed became infected with Covid-19 at a later date.
Of 592 people who had both Covid-19 vaccine doses and were followed for more than a month, 31 (5%) went on to develop long Covid, which was defined as illness lasting four weeks or more after a positive test.
By comparison, in the unvaccinated control group long Covid was reported in 11%, a paper in The Lancet Infectious Diseases reported.
The team found that in addition to a 50% reduction in long Covid, almost all symptoms were less common in vaccinated groups compared with non-vaccinated.
And Covid was less severe as measured by the number of symptoms in the first week of infection and the need for hospitalisation after first or second vaccine dose compared with unvaccinated participants, the results showed.
Some groups were more at risk of breakthrough infections than others including frail older adults and those living in deprived areas, particularly if they had one had one jab.
The researchers noted that the increased incidence of asymptomatic or minimally symptomatic infection in vaccinated participants underlines the importance of individuals who interact with unvaccinated or clinically vulnerable groups such as healthcare workers and social care workers continuing to regularly take tests for SARS-CoV-2 even when fully vaccinated.
And they concluded that their findings ‘might support caution around relaxing physical distancing and other personal protective measures in the post-vaccination era’, particularly in those at risk.
Study lead Dr Claire Steves from Kings College London, said people at increased risk needed to be prioritised for booster jabs.
‘In terms of the burden of long Covid, it is good news that our research has found that having a double vaccination significantly reduces the risk of both catching the virus and if you do, developing long-standing symptoms.’
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