- Full vaccination reduced the risk of long COVID after infection by 47%, a UK study suggested.
- However, partial vaccination did little to reduce this risk, the study said.
- Vaccines are already proven to protect against infection and severe cases.
Being fully vaccinated can halve the risk of developing long-lasting symptoms from a COVID-19 infection, also known as "long COVID," a new UK study suggested.
The study, published in the peer-reviewed journal The Lancet Infectious Diseases on Wednesday, used data from the ZOE COVID study, which uses an app to track self-reported COVID-19 symptoms from more than 4 million people in the UK.
Of those participants, 971,504 were fully vaccinated, and fewer than 0.2% — 2,370 — of them caught COVID-19 at least a week after their second dose, the study said.
Thirty-one out of 592 people (5.2%) who recorded breakthrough infections after two doses of vaccine, and were eligible to be included in the study's analysis, reported symptoms for more than 28 days. That compared to 55 people who had long-lasting symptoms out of a control group of 482 unvaccinated people (11.4%).
With that data, the study said that those who did get infected after two doses of vaccine were 47% less likely to have COVID-19 symptoms lasting longer than 28 days. Fever, persistent cough, loss of smell, and fatigue were the long-lasting symptoms most commonly reported by the participants, the study said.
However, being partially vaccinated — meaning having one dose out of a two-dose vaccine — did little to reduce the risk of developing long COVID, the study found.
The study looked at data from December 2020 to early July 2021, a time frame in which the Alpha variant was dominant in the UK and the beginning of the Delta variant wave in the country. The study did not break down the data about the infections by variant.
The same study also suggested that fully vaccinated people were almost twice as likely to have no symptoms than unvaccinated people if they caught COVID-19.
Vaccines have already been proven to help protect against COVID-19 infection, and reduce the risk of developing a severe disease. While breakthrough infections can happen, they tend to be milder in people who are fully vaccinated.
"Vaccinations are massively reducing the chances of people getting long COVID in two ways," said Professor Tim Spector of King's College London, one of the study's authors, per Sky News.
"Firstly, by reducing the risk of any symptoms by eight-to-10-fold, and then by halving the chances of any infection turning into long COVID, if it does happen."