Why some continue to suffer Covid-19 symptoms after recovery
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Recovered Covid-19 patients training on exercise machines at John Paul II Specialist Hospital in Krakow, Poland, during rehabilitation therapy for "long Covid" patients. Some people who have survived Covid-19 find that they continue to experience symptoms such as fatigue, shortness of breath, chest pain and "brain fog" even after recovering from the infection.
PHOTO: AGENCE FRANCE-PRESSE
Many who survive Covid-19 find themselves confronted with another challenge - recovering from "long Covid", which involves residual symptoms such as fatigue and chest pain weeks and months after the infection.
The Straits Times delves into why this happens, how prevalent it is and if vaccination will alleviate any of the lingering symptoms.
Q: What is "long Covid" and what do we know about it?
A: It is a condition where some people continue to experience Covid-19 symptoms for longer than usual, even after recovering from the infection.
Fatigue, shortness of breath, chest pain, joint aches and "brain fog" - where one's thinking is sluggish - are some of the commonly described problems that emerge or linger four weeks or more after an infection.
Long Covid is a serious concern from a societal perspective, adding to the hidden toll of the pandemic years later, said Associate Professor Alex Cook, vice-dean of research at the National University of Singapore's Saw Swee Hock School of Public Health.
It justifies the strong measures taken to cut community transmission since the beginning of the pandemic and to prevent people from being infected in the first place.
The prevalence has been estimated from about one in 10 to one in three cases, though the symptoms are quite diverse, and it is difficult to be sure how many people experience these symptoms and for how long, Prof Cook said.
When Prof Cook and his team early this year interviewed recovered foreign workers who lived in dormitories, about 20 per cent of them reported still having side effects.
This was more than six months after they had been infected in the middle of last year, when Singapore was battling outbreaks in workers' dormitories.
Though data is slowly emerging, researchers have yet to study enough patients over a long duration to gauge the full range of long-term effects.
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"There really is a pressing need to study the problem in depth and to alleviate any residual symptoms," Prof Cook said.
Q: What causes long Covid and will vaccination alleviate it?
A: The main reason behind Covid-19's long tail is related to the autoimmune response of the body. When a patient is infected, he may develop an overactive immune response. The long-term side effects might be due to the body attacking itself, an issue that vaccination is unable to resolve.
A large survey of more than 800 people has recently suggested that mRNA vaccines, in particular, are beneficial in alleviating long Covid.
The analysis, which is yet to be peer-reviewed, was based on a survey conducted by advocacy group LongCovidSOS that involved 812 people with long Covid in Britain and internationally, The Guardian reported on Tuesday.
Generally, the survey found that those who received mRNA vaccines, such as the Pfizer-BioNTech and Moderna jabs, reported greater improvements in symptoms than those who received an adenovirus vaccine, such as the AstraZeneca-Oxford jab.
Researchers say more data and time are needed to get a full understanding of what happens in the long term when a vaccinated person is infected but displays only mild symptoms.
Q: Do other viruses also have similar effects?
A: Yes, it can happen with certain viral infections, such as the common cold, influenza, HIV, measles and hepatitis B.
A Canadian study identified 21 healthcare workers from Toronto who had post-viral symptoms for as long as three years after being infected by severe acute respiratory syndrome (Sars) in 2003 and were unable to return to their usual work.
Some people who were hospitalised with Sars in Hong Kong still had impaired lung function two years later, a study of 55 patients published in medical journal Respirology in 2010 found.
But it remains unclear whether this finding can be translated into what we know of Covid-19.
