It’s been nearly two years that coronavirus disease (Covid-19) pandemic began across the globe. While multiple vaccines with high efficacy rate are currently available, their protection capability in the face of varied threats posed by the virus remains somewhat ambiguous. One such threat is long Covid or post-acute sequelae SARS-CoV-2 infection (PASC).
According to WebMD, long Covid can be defined as having lingering symptoms of the infection weeks or even months after one starts to recover from it. A recent study by researchers of University of Michigan revealed that over 40 per cent of Covid-19 survivors around the world are estimated to have suffered from long Covid.
Does vaccination protect against long Covid?
Although vaccination helps against the virus, experts believe that it doesn’t curtail the risk of long Covid. According to a report in Nature, physiotherapist David Putrino said a dozen of his clients experienced long Covid from ‘breakthrough infections’ wherein vaccinated individuals catch the infection.
One of the causes of long Covid is the broad immune response triggered by the initial infection, which can produce antibodies and several other immunological reactions against the body’s own tissues. Researchers and data suggested that vaccination could only decrease the likelihood of this scenario, and also that protection against long Covid is partial.
One of the largest studies gathered so far from 1.2 million people, who were inoculated with at least one dose of Covid-19 vaccine, found that a full-two dose of vaccination decreased the risk of long Covid by about half among those who had breakthrough infections. However, the Nature journal report noted, the study constituted more men than women, and fewer individuals from the lower-income regions.
Is it possible to know the extent and of long Covid’s risk?
Immunologist Petter Brodin at Stockholm’s Karolinska Institute said that determining the risk of long Covid from breakthrough infections is challenging as several people with mild or asymptomatic infections may not even be tested for Covid-19, according to the Nature report.
“Doing any kind of assessment of how many people develop long-term symptoms after they are vaccinated is going to be incredibly difficult,” he added.
What remains unknown regarding the interlink between vaccine and long Covid?
A large study, yet to be peer reviewed, revealed that vaccination didn’t protect against multiple conditions related to long Covid. In reference to this, immunologist Akiko Iwasaki at Yale University in Connecticut, said that results of these studies are disappointing.
“I honestly thought the vaccine would protect against long Covid much more extensively,” she said.
With vaccination programmes continuing, researchers will gain a better insight into the mechanism of vaccines and variants that affect long Covid rates and severity. For example, in October, the UK branch for the National Statistics, which is assembling data on long Covid, reported that the first shot of the Covid-19 vaccine was associated with 13 per cent decrease in self-reported long Covid symptoms among those who already had the condition. Meanwhile, the second jab produced an additional 9 per cent drop relative to the first.