Long COVID risk reduced by almost half after double vaccine dose

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Receiving two COVID-19 vaccine doses reduces a person’s risk of experiencing long COVID by almost half, a new study has shown.

Research led by King’s College London determined that, if a person should catch COVID-19 after being double vaccinated, they are 49% less likely to experience long-lasting symptoms of the virus – also known as long COVID.

The study has been published in The Lancet Infectious Diseases.

The research team analysed data from participants who logged their symptoms, tests, and vaccines on the UK ZOE COVID Symptom Study app between 8 December 2020 and 4 July 2021, including 1,240,009 (first dose) and 971,504 (second dose) vaccinated UK adults. The researchers assessed a range of factors, including age, frailty, and areas of deprivation, and compared that with post-vaccination infection.

As well as a significantly reduced risk of developing long COVID, the study findings also revealed that two vaccine doses resulted in fewer hospitalisations (73% less likely) and a lower burden of acute symptoms (31% less likely) among those fully vaccinated.

Milder symptoms

The nature of the most common symptoms reported after two vaccine doses – such as loss of smell, fever, and headaches –were similar to unvaccinated adults. However, all of these symptoms were milder and less frequently reported by people who were vaccinated, and individuals were half as likely to get multiple symptoms in the first week of illness. Sneezing was the only symptom that was more commonly reported in vaccinated people with COVID-19.

At-risk groups

The study highlighted that people living in most deprived areas were at greater risk of infection after a single vaccination. While age on its own was not a risk factor, individuals who had health conditions that limited their independence – such as frailty – were up to two times more likely to contract COVID-19 infection after vaccination and to get sick.

The researchers say that these findings stress the importance of targeting at-risk groups. To help address this issue, the study authors recommend implementing strategies such as a booster programme, infection control measures, and carrying out more research into the immune response to vaccination.

Lead researcher Dr Claire Steves, from King’s College London, said: “In terms of the burden of long COVID, it’s 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 longstanding symptoms. However, among our frail, older adults and those living in deprived areas, the risk is still significant and they should be urgently prioritised for second and booster vaccinations.”

Professor Tim Spector, from King’s College London and Lead investigator of ZOE COVID Study, commented: “Vaccinations are massively reducing the chances of people getting long COVID in two ways. Firstly, by reducing the risk of any symptoms by eight- to ten-fold and then by halving the chances of any infection turning into long COVID, if it does happen. Whatever the duration of symptoms, we are seeing that infections after two vaccinations are also much milder, so vaccines are really changing the disease and for the better. We are encouraging people to get their second jab as soon as they can.”

Long COVID research

Health and Social Care Secretary Sajid Javid said: “COVID-19 vaccines have saved more than 105,000 lives and prevented over 24 million infections in England alone. This research is encouraging, suggesting vaccines are not only preventing deaths but could also help prevent some of the longer-lasting symptoms.

“We have invested £50m in research to better understand the lasting effects of COVID-19 and over 80 long COVID assessment services have opened across England as part of a £100m expansion of care for those suffering the effects.

“It is clear vaccines are building a wall of defence against the virus and are the best way to protect people from serious illness. I encourage everyone who is eligible to come forward for both of their jabs as quickly as possible.”


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