New Data Suggest Vaccination Reduces Risk of Developing Long Covid

The incidence of postacute sequelae of SARS-CoV-2 infection, also known as long COVID, decreased over time during the first year of infection, with the risk decreasing further among those who were vaccinated, according to results of a study published in The New England Journal of Medicine.¹

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“Long COVID is not over,” Ziyad Al-Aly, MD, clinical epidemiologist at Washington University, said in a statement. “We cannot let our guard down. This includes getting annual COVID vaccinations because they are the key to suppressing long COVID risk. If we abandon vaccinations, the risk is likely to increase.”²

According to the CDC, long COVID is “a chronic condition that occurs after SARS-CoV-2 infection and is present for at least 3 months. Long COVID includes a wide range of symptoms or conditions that may improve, worsen, or be ongoing.” Symptoms of long COVID can vary, and severity can range from mild to severe. The most commonly reported symptoms are brain fog, fatigue, and post-exertional malaise; however, other symptoms can range from respiratory, cardiovascular, neurological, and digestive.³

The CDC added that individuals who have had COVID-19 could be more likely to develop new or worsening conditions, including diabetes, cardiovascular disease, blood clots, and neurological conditions. Further, research has shown that women who experience mild inflammation when infected with COVID-19 are more likely to experience symptoms of long COVID, with associated symptoms such as muscle ache, low mood, and anxiety.^3,4

The study authors stated that the evolution of COVID-19 strains may have affected the risk and burden of long COVID. Investigators aimed to estimate the incidence of long COVID 1 year after infection in the pre-delta, delta, and omicron periods of the pandemic, using health records of 441,583 individuals infected with COVID-19 and 4,748,504 non-infected individuals. Data were collected between March 2020 and January 31, 2022, from the Department of Veterans Affairs.¹

Among individuals who were unvaccinated, the cumulative incidence of long COVID was 10.42 events per 100 persons for the pre-delta phase, 9.51 events per 100 persons in the delta phase, and 7.76 events per 100 persons in the omicron phase, according to the authors. For vaccinated individuals, the cumulative incidence was 5.34 in the delta phase and 3.5 in the omicron phase. According to the study authors, the decomposition analyses demonstrated that there were 5.23 fewer event per 100 persons at 1 year during the omicron era compared to the pre-delta and delta eras combined, indicating a 28.11% decrease attributed to variant-related effects. Further, 71.89% was attributed to vaccines.¹

“You can see a clear and significant difference in risk during the delta and omicron eras between the vaccinated and unvaccinated,” said Al-Aly. “So, if people think COVID is no big deal and decide to forgo vaccinations, they’re essentially doubling their risk of developing long COVID.”²

References

1. Xie Y, Choi T, Al-Aly Z. Postacute Sequelae of SARS-CoV-2 Infection in the Pre-Delta, Delta, and Omicron Eras. NEJM. 2024. doi:10.1056/NEJMoa2403211

2. Sauerwein K. Risk of long COVID declined over course of pandemic. News release. Washington University in St. Louis. July 17, 2024. Accessed July 17, 2024. Email.

3. Centers for Disease Control and Prevention. Long COVID Basics. June 11, 2024. Accessed July 16, 2024. https://www.cdc.gov/coronavirus/2019-ncov/long-term-effects/index.html

4. Ferruggia K. Researchers Link Inflammation With Long Covid Symptoms in Women. Pharmacy Times. November 9, 2023. Accessed July 16, 2024. https://www.pharmacytimes.com/view/researchers-link-inflammation-with-long-covid-symptoms-in-women