New research has identified a clear benefit of the COVID-19 vaccine: if people are infected, the vaccine cuts the risk of developing long COVID by half. Millions of people are still affected by long COVID, a disorder that can have a serious impact on a person's quality of life, and which may impair their ability to work or function normally. Factors that can increase the risk of long COVID were also identified in this study. The findings have been reported in JAMA Internal Medicine.
Long COVID is more likely to happen in people who have a case of COVID-19 that requires hospitalization, and in those who have asthma, type 2 diabetes, COPD, coronary heart disease, anxiety and depression, or are taking immunosupressants. People who are over age 40, smoke cigarettes, or are overweight are also more likely to have long COVID.
"Long COVID is a complex condition that develops during or after having COVID, and it is classified as such when symptoms continue for more than 12 weeks," said study co-author Professor Vassilios Vassiliou of the University of East Anglia, among other appointments.
It's thought that more than two million people in the UK have long COVID, which affects people in various ways. Some of the most common symptoms are coughing, breathlessness, heart palpitations, severe fatigue, and headache. There are sometimes other symptoms too, which could include insomnia, brain fog, dizziness, depression and anxiety, chest pain, joint pain, tinnitus, loss of appetite, and changes in a person's sense of smell or taste.
The researchers were interested in identifying the factors that could increase or decrease a person's risk of developing long COVID. In this work, they assessed data that had been collected from around the world, and which was reported in 41 different studies; this included 860,783 patients. The scientists identified some of the long COVID risk factors.
"We found that female sex, older age, increased BMI and smoking are associated with an increased risk of long COVID," said Vassiliou. "In addition, comorbidities such as asthma, COPD, type 2 diabetes, coronary heart disease, immunosuppression, anxiety and depression are also associated with increased risk." People who had a severe illness during the acute phase of COVID-19, and spent time in the hospital were also at greater risk of long COVID.
However, vaccination had a significant impact on the reduction of long COVID risk. "Conversely, it was reassuring to see that people who had been vaccinated had significantly less risk - almost half the risk - of developing long COVID compared to unvaccinated participants, said Vassiliou.
This study can help scientists and clinicians understand who might get going COVID, and show patients why vaccinations are beneficial. There are other risk factors that people can be told about with health campaigns, added the researchers; people could be encouraged not only to get vaccinated, but also to stop smoking and manage their weight.
This research agrees with a previous study in The Lancet Infectious Diseases. However, it came to a very different conclusion from a 2022 study reported in Nature Medicine that indicated that long COVID risk was only slightly reduced by vaccination; the Nature Medicine study focused on about 34,000 people who had been vaccinated but had a breakthrough case of COVID-19, so it included far fewer people than this latest report.
