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COVID-19 vaccine after infection reduces risk of Long Covid



A new study involving Southampton’s Dr Nisreen Alwan suggests vaccination could help people with Long Covid.


There is evidence that shows people vaccinated against COVID-19 are less likely to get Long Covid. What is less clear is whether vaccination helps people who already have Long Covid.


This study, published in The BMJ, showed COVID-19 vaccination after infection with the virus is associated with a reduced likelihood of Long Covid symptoms.


Tracking Long Covid


The latest survey by the UK’s Office for National Statistics (ONS) shows that 44% of people who report Long Covid have had symptoms for at least one year. Two thirds of these report symptoms severe enough to limit their day-to-day activities.


The researchers drew on ONS data for 28,356 adults aged 18-69 years who received at least one COVID-19 vaccine dose after testing positive for the virus.


They tracked Long Covid symptoms over a seven-month follow-up period, starting in February 2021. Almost a quarter of the participants (24%) reported symptoms of any severity at least once during this time.


Less risk after vaccination


They found a single vaccine dose was associated with an initial 13% decrease in the odds of Long Covid. It is unclear from the data whether this improvement was sustained over the following 12 weeks, until a second vaccine dose was given.


A second dose was associated with a further 9% decrease. This improvement lasted, on average, for at least nine weeks.


Similar results were also found when the focus was on Long Covid severe enough to result in limitation of day-to-day activities.


Dr Alwan said: “Our study indicates evidence of sustained average improvement in Long Covid symptoms after the second dose of the COVID19 vaccine, but within a limited follow-up period.


“Vaccination may help lessen Long Covid symptoms impacting on daily life in some individuals, but given the episodic nature of this illness longer follow-up is needed.”


Due to the study’s observational design, causality cannot be inferred. The researchers also cannot rule out the possibility that other unmeasured factors, such as those related to take-up of a second vaccine dose, may have affected their results.


However, the results were consistent after taking account of various factors, including sociodemographic characteristics, health related factors, vaccine type, or duration from infection to vaccination, suggesting that they withstand scrutiny.