COVID-19 jabs help reduce long-term symptoms

COVID-19 vaccination appears to reduce the odds of long COVID symptoms, with continuous improvement following a second dose, at least in the first few months after the shot, suggests a study.

“We found that vaccination against COVID-19 is associated with a decrease in the likelihood of continuing to experience long COVID symptoms in adults aged 18–69 years, and this appeared to be sustained after a second vaccine dose,” the researchers said.

 This observational cohort study was conducted in a community-dwelling population in the UK to examine the associations between COVID-19 vaccination and long COVID symptoms in adults with SARS-CoV-2 infection before vaccination.

A total of 28,356 participants (mean age 46, 55.6 percent women, 88.7 percent White) in the Office for National Statistics COVID-19 Infection Survey who received at least one dose of an adenovirus vector or mRNA vaccine after testing positive for the virus were included in the analysis.

Of the participants, 6,729 (23.7 percent) reported long COVID symptoms of varying severity at least once during follow-up. Median follow-up was 141 days from first vaccination and 67 days from second vaccination. [BMJ 2022;377:e069676]

A first vaccine dose resulted in an initial 12.8-percent reduction (95 percent confidence interval [CI], ‒18.6 to ‒6.6; p<0.001) in the likelihood of long COVID, with subsequent data compatible with both increases and decreases in the trajectory (0.3 percent per week, 95 percent CI, ‒0.6 to 1.2; p=0.51).

Moreover, a second dose led to an initial 8.8-percent decrease (95 percent CI, ‒14.1 to ‒3.1; p=0.003) in the likelihood of long COVID, with a subsequent reduction by 0.8 percent per week (95 percent CI, ‒1.2 to ‒0.4; p<0.001).

There was no statistical evidence of heterogeneity seen in the associations between vaccination and long COVID by sociodemographic characteristics, health status, hospital admission with acute COVID-19, vaccine type, or duration from SARS-CoV-2 infection to vaccination.

“This observational study was unlikely to have been sufficiently powered to detect these associations, however, particularly given the multiplicity of testing, an absence of evidence does not necessarily imply evidence of absence,” the researchers said.

Resetting autoimmune processes

The principal finding of a decrease in the odds of experiencing long COVID symptoms following a second dose supports hypothesized biological mechanisms, according to the researchers.

“People with long COVID who experience dysregulation of the immune system may benefit from autoimmune processes being ‘reset’ by vaccination (although whether this is long lasting remains to be established), while any residual viral reservoir may also be destroyed by the antibody response,” they explained. [medRxiv 2021;doi:10.1101/2021.07.21.21260391]

Immunological phenotyping shows differences between patients with persistent symptoms after SARS-CoV-2 infection and healthy controls. [BMC Med 2022;20:26]

“The presence of autoantibodies against interferon type I or autoimmune processes triggered by SARS-CoV-2 through molecular mimicry has been proposed as a manifestation of immune dysregulation in long COVID, possibly similar to autoimmune rheumatic diseases,” the researchers said. [Clin Rheumatol 2022;41:957-958]

“Another proposed mechanism is the persistence of viral antigen modifying the immune response months after infection. In this scenario, it is reasonable to hypothesize that COVID-19 vaccination may be beneficial,” they added. [Nature 2021;591:639-644]

Further research is warranted to assess the long-term association between vaccination and long COVID, particularly the impact of the Omicron variant, booster doses, and reinfections. Future studies should also elucidate the biological mechanisms behind improvement in symptoms after vaccination, which may help in the development of treatments for long COVID, according to the researchers.