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This award-winning blog supplements the articles in Hospital Infection Control & Prevention.

Eureka! Vaccination Can Prevent Long COVID

Long C Getty Images 1403673178

By Gary Evans, Medical Writer

Could long COVID — a horrific condition that anyone would want to avoid — shake people out the malaise of vaccine apathy if not outright distrust?

Evidence is accumulating that receiving the COVID-19 vaccination before initially being infected with SARS-CoV-2 can significantly reduce the risk of long COVID in adults and children.

Approximately 13 million people in the United States have long COVID. That is based on the U.S. Census Bureau estimate that 9.5% of the 134 million adults who have been infected with SARS-CoV-2 were experiencing long COVID in October 2023.

Long COVID is a complex presentation, as it may be multi-systemic, alternately relapsing and remitting, and progress over time. Its presentation can be so unusual that some patients feel that others do not believe they have long COVID, which runs the gamut from neurological symptoms like brain fog to physical symptoms like muscle and joint pain. Multiple organs and body systems may be affected, including the heart, lungs, digestive tract, and skin.

Good News from Sweden

A recently published study found that vaccination before initial SARS-CoV-2 infection is protective against long COVID in a stepwise fashion, from 21% for one dose, 59% for two doses, and a striking 73% for three or more doses.

An accompanying editorial said the study shows that COVID-19 vaccines “have a clear and clinically important protective effect against post-COVID-19 condition[s] (PCC).”

The population study in Sweden looked at 589,722 people 18 years or older who had COVID-19 between Dec. 27, 2020 to Feb. 9, 2022.

Individuals who had received at least one dose of a COVID-19 vaccine before infection were considered vaccinated. The primary outcome was a clinical diagnosis of PCC.

Of 299,692 vaccinated individuals with COVID-19, 1,201 (0.4%) had a diagnosis of long COVID during follow-up, compared with 4,118 (1.4%) of 290,030 unvaccinated individuals.

“COVID-19 vaccination with any number of doses before infection was associated with a reduced risk of PCC, with a vaccine effectiveness of 58%,” the authors reported.

“Of the vaccinated individuals, 21,111 received one dose only, 205,650 received two doses, and 72,931 received three or more doses.”

Again, there was protection across all groups, but those who had received three or more vaccine doses had the impressive 73% reduced risk of long COVID. “The results of this study suggest a strong association between COVID-19 vaccination before infection and reduced risk of receiving a diagnosis of PCC,” they concluded.

In addition to the obvious benefits revealed, the study also serves to confirm the existence of long COVID, which some have questioned given the variety of symptoms and the absence of established diagnostic biomarkers, the authors of the accompanying editorial observed. Moreover, the findings also underscore the importance of vaccines for future pandemics.

“Future pandemic preparedness plans should continue to prioritize prompt manufacture, evaluation, and distribution of vaccines, and mass vaccination to reduce a pandemic’s impact on health,” the editorial authors report. “Although vaccines have adverse effects, including some that are rare but can lead to considerable disability, the benefits of vaccination for both individuals and populations far outweigh the risks.”

There is no shortage of barriers and obstacles, including COVID-19 vaccine uptake in the United States of a paltry 19% as of Dec. 30, 2023, according to the Centers for Disease Control and Prevention.

“There is currently no standardized internationally recognized case definition,” explained Anna Yousaf, MD, a medical offer at the CDC.

Thus, the CDC and public health collaborators have developed a basic definition of long COVID as conditions and symptoms that continue or develop after acute SARS-CoV-2 infection and are present four weeks or longer afterward.

“This definition recognizes that post-COVID conditions may be multi-systemic, relapsing, or remitting and may progress over time,” Yousaf said at the IDWeek 2023 meeting in Boston.

Rare but Real Risk

A meta-analysis of recent studies estimates that 1% to 3% of children have one or more long COVID symptoms after SARS-CoV-2 infection.

“The CDC estimates that over 65 million children in the U.S. have had SARS-CoV-2 infection since January of 2023, meaning there’s the potential for thousands of children in the U.S. to have post-COVID conditions,” Yousaf said. “Data in adults show that COVID-19 vaccination prior to [SARS-CoV-2] infection does reduce the likelihood of post-COVID conditions. There’s very little data on COVID-19 vaccination in children in post-COVID conditions.”

Using an existing CDC database, Yousaf and colleagues winnowed out 622 children aged 5-17 years. Twenty-eight children had long COVID and 594 controls did not develop the condition.

“The outcome of interest was an estimate of the odds of one or more post-COVID condition, one or more respiratory post-COVID condition symptom, or one or more non-respiratory post-COVID condition symptom in COVID-19 vaccinated children compared to unvaccinated children,” she said. “We found that mRNA [messenger ribonucleic acid] COVID-19 vaccination prior to [SARS-CoV-2] omicron variant infection appeared to be protective against post-COVID conditions in children, with a 34% reduced likelihood of one or more post-COVID conditions, a 47% reduced likelihood of respiratory post-COVID conditions and a 48% reduced likelihood of two or more post-COVID condition symptoms. These data support COVID-19 vaccination for children," she concluded.

Parents should be apprised of this finding at the nearest opportunity, as the CDC reports that less than 10% of children in this general age range have received the latest COVID-19 monovalent vaccine. A preventive effect is much less likely to occur if children or adults have already been infected before vaccination, nor is treatment with vaccination likely to resolve long COVID.

“[These findings may] encourage increased pediatric vaccine uptake in a population that typically does not experience severe COVID-19 illness,” Yousaf said.

For more on this story, see the next issue of Hospital Infection Control & Prevention.

Gary Evans, BA, MA, has written numerous articles on infectious disease threats to both patients and healthcare workers for more than three decades. He has been honored for excellence in analytical reporting five times by the National Press Club in Washington, DC.