New Delhi: Two or more doses of the Covid vaccine can not only reduce the severity of the disease but also reduce long-term side-effects of Covid — commonly known as long Covid — to a significant extent, a study from Israel that is yet to be peer-reviewed, shows. Moreover, this was more pronounced in older age groups, the study found.
Researchers from Bar-Ilan University studied 951 individuals who had tested positive for Covid. Of these, 637 (67 per cent) were fully vaccinated. The most commonly reported symptoms were fatigue (22 per cent), headache (20 per cent), weakness (13 per cent) and persistent muscle pain (10 per cent). The researchers found that the fully vaccinated (two or more doses) individuals were less likely than unvaccinated individuals to report any of these symptoms by 64 per cent, 54 per cent, 57 per cent, and 68 per cent respectively.
“Vaccination with at least two doses of Covid-19 vaccine was associated with a substantial decrease in reporting the most common post-acute Covid-19 symptoms. Our results suggest that, in addition to reducing the risk of acute illness, Covid-19 vaccination may have a protective effect against long Covid,” the researchers concluded in a pre-print paper uploaded on the server medRxiv.
The effect was not seen in people who had received only one dose of the vaccine.
Israel has been one of the fastest movers on vaccinations. Vaccinations started in December 2020, and by January 2022, approximately 63.6 per cent of the entire population had received two doses of the Pfizer vaccine and 45.6 per cent had received a third dose of Covid-19 vaccines, available in Israel from June 2021.
The country has now started administering a fourth dose of the Covid shot to healthcare workers, senior citizens and those with compromised immunity. The findings reveal some unintended positive consequences of Covid vaccines as they were tried only on their capacity to reduce death, severe disease and hospitalisation.
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Common long Covid symptoms in India
In October 2021, the World Health Organization (WHO) defined long Covid as a condition which “occurs in individuals with a history of probable or confirmed SARS-CoV-2 infection, usually 3 months from the onset of COVID-19 with symptoms that last for at least 2 months and cannot be explained by an alternative diagnosis. Common symptoms include fatigue, shortness of breath, and cognitive dysfunction, but also others and generally have an impact on everyday functioning.”
Among the long Covid symptoms that have been detected among Indian patients, the most important are impairment of lung function, cardiovascular sequelae and neuropsychiatric illnesses such as anxiety, depression, and post-traumatic stress disorder.
Age, comorbidities risk factors for long Covid
The Israeli researchers in the pre-print paper highlighted the fact that while the risk factors for long Covid are not fully understood, among some that are recognised to trigger more severe symptoms over the long term are age, hypertension, obesity, psychiatric disorders and immunosuppression.
Significantly, they found that the beneficial effect of vaccines on long Covid was more significant in people of older age groups. “Our analysis does not allow us to establish why the beneficial effect of the Covid-19 vaccine on long-term symptoms seems to be stronger in older age groups. A plausible explanation for the association found in the older individuals could be that younger individuals have more physiological reserve and are therefore able to recover on their own, which is not the case in older adults. Other studies have reported that frailty was associated with both age and worse outcomes following SARS-CoV-2 infection,” they wrote.
They also argued that it is possible to partially explain the effect of vaccines on long Covid of people across age groups by the fact that they develop less severe symptoms.
(Edited by Saikat Niyogi)
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