Vaccine Effectiveness Analyzed Against Long COVID-19

Researchers recently performed a systematic literature review and meta-analysis on the effectiveness of COVID-19 vaccination against post–COVID-19 conditions, known as long COVID.

Published by Cambridge University Press on December 6, 2022, this analysis found COVID-19 vaccination, both before and after having COVID-19, significantly decreased post–COVID-19 conditions for the circulating SARS-CoV-2 variants during the study period.

The pooled prevalence of post–COVID-19 conditions was 39.1% among those unvaccinated and 37.6% among those vaccinated at least once. 

However, the meta-analysis's average COVID-19 vaccine effectiveness was 29.2% (95% CI, 27.5%–30.8%).

The vaccine effectiveness was 35.3% (95% CI, 32.3%–38.1%) among those who received the COVID-19 vaccine before having COVID-19 and 27.4% (95% CI, 25.4%–29.3%) among those who received it after having COVID-19.

This study searched PubMed, CINAHL, EMBASE, Cochrane Central Register of Controlled Trials, Scopus, and Web of Science from December 2019, to April 27, 2022, and included six studies that evaluated individuals who received at least one dose of Pfizer/BioNTech, Moderna, AstraZeneca, or Janssen vaccine.

In conclusion, COVID-19 vaccination before and after having COVID-19 provided a low but statistically significant decrease in post–COVID-19 conditions for the variants circulating during the study period.

To better understand vaccine effectiveness against post–COVID-19 conditions, more observational studies are needed to evaluate other types of COVID-19 vaccines (e.g., inactivated virus), vaccination after having COVID-19, vaccine effectiveness of a booster dose, vaccine effectiveness of mixing COVID-19 vaccines, and genomic surveillance.

And a more standardized definition of post–COVID-19 conditions is also needed both for research and clinical purposes.

This study had several limitations.

First, most of the included studies in the meta-analysis were observational studies, which are subject to multiple biases.

No financial support was provided relevant to this article, and all authors report no relevant conflict of interest.

Note: The U.S. CDC's Morbidity and Mortality Weekly Report highlights the latest scientific information on the safety and effectiveness of COVID-19 vaccines

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