Vaccination after infection with Covid-19 causing SARS-CoV-2 is associated with a decrease in the likelihood of long Covid symptoms, as per a large study of UK adults published by The BMJ on Friday.
It stressed that causality cannot be inferred from this observational evidence, but said vaccination “may contribute to a reduction in the population health burden of long Covid, at least in the first few months after vaccination.” Thus making the case for continuing with vaccination strategy.
Vaccines against Covid-19 are effective at reducing rates of coronavirus infection, transmission, hospital admission, and death.
Evidence also suggests that long Covid is reduced in those who are infected after vaccination, but the effectiveness of vaccination on pre-existing long Covid is less clear.
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 whom report symptoms severe enough to limit their day-to-day activities.
So a team of researchers set out to estimate associations between Covid-19 vaccination and long Covid symptoms in adults with SARS-CoV-2 infection before vaccination.
They drew on ONS data for 28,356 adults aged 18-69 years (average age 46; 56% women; 89% white) who received at least one Covid-19 vaccine dose after testing positive for SARS-CoV-2 infection.
They then tracked the presence of long Covid symptoms over a seven month follow-up period (February to September 2021).
Long Covid symptoms of any severity were reported by 6,729 participants (24%) at least once during follow-up.
Before vaccination, the odds of experiencing long Covid changed little over time.