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Center for Infectious Disease Research and Policy
Mary Van Beusekom | News Writer | CIDRAP News
A pair of new studies describe long-COVID findings, one from Spain showing that nearly 40% of bilateral pneumonia patients had impaired lung diffusion 1 year after hospitalization, and the other from England demonstrating that double-vaccinated adults were 41% less likely than their unvaccinated peers to report symptoms 3 months or more after infection.
Spain: 23% had abnormal 12-month CT scans
As part of a study of adult patients admitted to 12 hospitals in Spain with bilateral COVID-19 pneumonia, researchers analyzed lung function and chest computed tomography (CT) findings 2, 5, and 12 months after hospital release, which was from May 1 to Jul 31, 2020. The findings were published yesterday in Respiratory Research.
Average age was 60.5 years, and 55.3% were men. A total of 377 patients completed 2-month follow-up, but pandemic restrictions shrunk the pool to 312 patients at 6 months and 284 at 12 months.
The patients were classified into one of three groups: mild (requiring supplemental oxygen through a mask or nasal prongs), severe (requiring noninvasive mechanical ventilation or a high-flow nasal oxygen cannula), or critical (requiring invasive mechanical ventilation).
At 2 months, 53.8% of all patients had impaired lung diffusion, falling to 46.8% at 6 months and 39.8% at 12 months. Lung diffusion, however, was significantly different between severity groups only at 2 months. Lung diffusion is the ability to pass oxygen into blood from the lungs and pass carbon dioxide from the blood back into the lungs.
Low measures of forced vital capacity (FVC), or the greatest volume of air that can be forcibly exhaled, was identified in 14.3% of the entire group at 2 months, 9.3% at 6 months, and 6.7% at 12 months. There were no significant differences in FVC in terms of severity or time since hospital release.
At 2, 6, and 12 months, 21.5%, 11.3%, and 9.8% of the cohort, respectively, had shortness of breath, and the link between shortness of breath and time since release was significant. Risk factors for impaired diffusion capacity at 12 months were increasing age (odds ratio [OR], 1.04) and female sex (OR, 6.22).
At 2 months, high-resolution chest CT was performed in 325 patients who had persistent shortness of breath and abnormal pulmonary function tests or chest radiologic tests. While 38.4% of patients showed complete resolution, 73.5% of the remaining patients (32% of the entire cohort) had ground-glass opacity, indicating impaired lung function.
Of the 200 patients with abnormal CT findings at 2 months, 78% underwent another CT at 12 months, revealing that 78.8% of these patients (27.4% of the cohort) had persistent CT abnormalities.
“Along with an increasing number of people affected [by COVID-19] over time, survival has improved since the start of the pandemic, but with the consequence that millions of survivors could be affected by pulmonary sequelae of COVID-19, which could lead to a clear deterioration in quality of life,” the authors wrote. “These findings confirm the need for follow-up of patients with severe SARS-CoV-2-induced pneumonia to clarify whether fibrotic changes may progress over time.”
UK: Fewer activity-limiting symptoms in vaccinated
In England, Office for National Statistics researchers examined rates of long COVID in adult participants in the UK COVID-19 Infection Survey from April 2020 to November 2021. The research was published yesterday in Open Forum Infectious Diseases.
In the study’s pilot phase, from April to August 2020, previous survey respondents and a random selection of people from national address lists were chosen for in-home interviews. All participants had tested positive for COVID-19 during the study period, and 3,090 had received at least two doses of the AstraZeneca/Oxford, Pfizer/BioNTech, or Moderna COVID-19 vaccines at least 14 days before infection. They were matched with an equal number of unvaccinated controls.
While 99.7% of controls were infected before May 17, 2021, when the SARS-CoV-2 Delta variant became dominant in the United Kingdom, 98.9% of vaccinated participants were infected during the Delta period. Median follow-up was about 97 days.
Of the 3,090 double-vaccinated participants, 294 (9.5%) reported long-COVID symptoms of any severity after at least 3 months, compared with 452 of 3,090 controls (14.6%) (adjusted OR [aOR], 0.59). Activity-limiting symptoms were reported by 170 (5.5%) double-vaccinees, compared with 268 (8.7%) controls (aOR, 0.59).
“We found that receiving two COVID-19 vaccinations at least two weeks before SARS-CoV-2 infection was associated with a 41% decrease in the odds of developing long COVID symptoms at least 12 weeks later, relative to not being vaccinated when infected,” the authors wrote.
The results highlight the need to increase population-level vaccine uptake, they added. “Studies with longer follow-up are needed to assess the impact of booster doses and the Omicron variant and to evaluate symptom trajectories beyond a single 12-week follow-up visit, particularly given the relapsing nature of long COVID,” the researchers concluded. “Further research into possible biological explanations behind our findings, which may inform therapeutic strategies for long COVID, is also required.”