US COVID-19 cases in first pandemic wave may have been 5 times higher
During the first US wave of the COVID-19 pandemic, there may have been almost 17 million undiagnosed COVID-19 infections in addition to the known 3 million cases, or about five times more than officially reported, according to a study in Science Translational Medicine yesterday.
The researchers conducted enzyme-linked immunoassay serologic tests for COVID-19 antibodies on 8,058 undiagnosed US adults from May 10 to Jul 31, 2020, and found that 304 (4.6%) had COVID-19 antibodies. This indicates that there were 4.8 undiagnosed infections for every diagnosed case during this period, the researchers say, adding about 16.8 million infections to the country's total.
The cohort was designed to reflect the US population.
Data showed that 14.2% of Black people had COVID-19 antibodies, compared with 2.5% of White people and 2.0% of Asian people. The mid-Atlantic region had the highest rate of people with COVID-19 antibodies (8.6%); higher rates were also found among city dwellers (5.3% vs 1.1% in the country), those under 45 (5.9%), and women (5.5% vs 3.5% in men). Those who worked from home (3%) and those with chronic conditions had the lowest levels of antibodies in their blood.
"Our data suggest a larger spread of the COVID-19 pandemic in the United States during the first six months than originally thought," the researchers write. "Our findings have implications for understanding SARS-CoV-2 spread, epidemiological characteristics of spread and prevalence in different communities, and could have a potential impact on decisions involved in vaccine rollout."
Jun 22 Sci Transl Med study
Young adults with mild acute infection may be at risk for long COVID
More than 60% of 312 COVID-19 patients had symptoms persisting after 6 months, including 52% of older teens and young adults with mild acute infections, according to a Nature Medicine study today.
The cohort consisted of 312 patients from Bergen, Norway, identified from Feb 28 to Apr 4, 2020, or about 82% of the city's total cases. About 80% were outpatients and the remaining were hospitalized; the median age was 46 years. Those hospitalized tended to be older, have a higher body mass index, and have more comorbidities.
At 6 months follow-up, 61% still experienced symptoms, which were independently associated with pre-existing chronic lung disease (eg, asthma; adjusted risk ratio [aRR], 1.14), female sex (aRR, 1.09), higher antibody titers at 2 months (aRR, 1.07), and severity of the acute illness (aRR, 1.06). Younger patients were less likely to have long COVID symptoms, but the researchers say that 52% of 61 outpatients from 16 to 30 years experienced some sort of symptom, most commonly loss of taste and/or smell (17), fatigue (13), shortness of breath (8), impaired concentration (8), and memory problems (7).
"It is worrying that non-hospitalized, young people (16–30 years old) suffer potentially severe symptoms, such as concentration and memory problems, dyspnea and fatigue, half a year after infection," the researchers write. "Particularly for students, such symptoms might interfere with their learning and study progress."
Jun 23 Nature Med study