Double COVID vaccination halves risk of Long COVID

April 28, 2020

Thanks to your contributions on the ZOE COVID Study app, we’ve found that having two or more doses of a COVID-19 vaccine not only significantly reduces a person’s risk of catching COVID-19, it’s also been found to reduce the severity of infection if someone does get infected. 

However, our latest research, which was published today in Lancet Infectious Diseases, has found that adults who received a double vaccination are in fact 47% less likely to get Long COVID should they contract a COVID-19 infection. 

Researchers at King’s College London analysed data from your contributions, including logged symptoms, tests and over 2 million vaccine doses on the UK ZOE COVID Study app between 8th December 2020 and 4 July 2021. The research team assessed a range of factors, including age, frailty and areas of deprivation and compared that with post-vaccination infection.

Double vaccination dramatically cuts hospital admissions and acute symptoms  

Our analysis also found that for those who contracted COVID-19 after two doses were: 

  • 73% less likely to be hospitalised
  • 31% less likely to experience acute COVID symptoms

Our research found that the most common symptoms were similar to unvaccinated adults. For example, anosmia (loss of smell), cough, fever, headaches, and fatigue. However, all these symptoms were milder and less frequently reported by people who were vaccinated, and they were half as likely to get multiple symptoms in the first week of illness. Sneezing was the only symptom which was more commonly reported in vaccinated people with COVID-19.

So whilst there is still a risk of contracting COVID-19 after double vaccination, there are clear reductions in the risk of being sent to the hospital, having really bad symptoms or going on to suffer from long duration symptoms. 

Health and Social Care Secretary, Sajid Javid had this to say about our research:
 "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 £50 million in research to better understand the lasting effects of COVID and over 80 long COVID assessment services have opened across England as part of a £100 million 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 their jabs as quickly as possible."

Who is at the highest risk of post vaccination COVID?

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 twice as likely to contract COVID-19 infection after double vaccination, and to get sick.

These findings demonstrate the need to assist at-risk groups. Frail adults have already been shown to be disproportionately affected by COVID-19. The King’s research team suggests strategies such as a timely booster programme, targeted infection control measures and more research into the immune response to vaccination in this group to help address the issue.

Our experts comment on the research

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 long-standing 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, Lead investigator of ZOE Covid Study comments: “Vaccinations are massively reducing the chances of people getting Long COVID in two ways. Firstly, by reducing the risk of any symptoms by 8 to 10 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 2nd jab as soon as they can.”

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