Ups and downs in COVID-19 data may be caused by data reporting practices

July 14, 2020

Washington, DC - July 14, 2020 - As data accumulates on COVID-19 cases and deaths, researchers have observed patterns of peaks and valleys that repeat on a near-weekly basis. But understanding what's driving those patterns has remained an open question.

A study published this week in mSystems reports that those oscillations arise from variations in testing practices and data reporting, rather than from societal practices around how people are infected or treated. The findings suggest that epidemiological models of infectious disease should take problems with diagnosis and reporting into account.

"The practice of acquiring data is as important at times as the data itself," said computational biologist Aviv Bergman, Ph.D., at the Albert Einstein College of Medicine in New York City, and microbiologist Arturo Casadevall, M.D., Ph.D., at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. Bergman and Casadevall worked on the study with Yehonatan Sella, Ph.D., at Albert Einstein, and physician-scientist Peter Agre, Ph.D., at Johns Hopkins.

The study began when Agre, who co-won the 2003 Nobel Prize in Chemistry, noticed that precise weekly fluctuations in the data were clearly linked to the day of the week. "We became very suspicious," said Bergman.

The researchers collected the total number of daily tests, positive tests, and deaths in U.S. national data over 161 days, from January through the end of June. They also collected New York City-specific data and Los Angeles-specific data from early March through late June. To better understand the oscillating patterns, they conducted a power spectrum analysis, which is a methodology for identifying different frequencies within a signal. (It's often used in signal and image processing, but the authors believe the new work represents the first application to epidemiological data.)

The analysis pointed to a 7-day cycle in the rise and fall of national new cases, and 6.8-day and 6.9-day cycles in New York City and Los Angeles, respectively. Those oscillations are reflected in analyses that have found, for example, that the mortality rate is higher at the end of the week or on the weekend.

Alarmed by the consistency of the signal, the researchers looked for an explanation. They reported that an increase in social gatherings on the weekends was likely not a factor, since the time from exposure to the coronavirus to showing symptoms can range from 4-14 days. Previous analyses have also suggested that patients receive lower-quality care later in the week, but the new analysis didn't support that hypothesis.

The researchers then examined reporting practices. Some areas, like New York City and Los Angeles, report deaths according to when the individual died. But national data publishes deaths according to when the death was reported--not when it occurred. In large datasets that report the date of death, rather than the date of the report, the apparent oscillations vanish. Similar discrepancies in case reporting explained the oscillations found in new case data.

The authors of the new study note that weekend interactions or health care quality may influence outcomes, but these societal factors do not significantly contribute to the repeated patterns.

"These oscillations are a harbinger of problems in the public health response," said Casadevall.

The researchers emphasized that no connection exists between the number of tests and the number of cases, and that unless data reporting practices change, the oscillations will remain. "And as long as there are infected people, these oscillations, due to fluctuations in the number of tests administered and reporting, will always be observed," said Bergman, "even if the number of cases drops."
ASM is keeping the pulse of the SARS-CoV-2 pandemic with the COVID-19 Research Registry of top-ranked research articles curated by experts. In the eye of a pandemic, this curated database will ensure that scientists, journalists and the public have an efficient way to find the timeliest and most valuable SARS-CoV-2/COVID-19 research from the latest journal articles and preprints. Visit
The American Society for Microbiology is one of the largest professional societies dedicated to the life sciences and is composed of 30,000 scientists and health practitioners. ASM's mission is to promote and advance the microbial sciences.

ASM advances the microbial sciences through conferences, publications, certifications and educational opportunities. It enhances laboratory capacity around the globe through training and resources. It provides a network for scientists in academia, industry and clinical settings. Additionally, ASM promotes a deeper understanding of the microbial sciences to diverse audiences.

American Society for Microbiology

Related Public Health Articles from Brightsurf:

COVID-19 and the decolonization of Indigenous public health
Indigenous self-determination, leadership and knowledge have helped protect Indigenous communities in Canada during the coronavirus disease 2019 (COVID-19) pandemic, and these principles should be incorporated into public health in future, argue the authors of a commentary in CMAJ (Canadian Medical Association Journal)

Public health consequences of policing homelessness
In a new study examining homelessness, researchers find that policy such a lifestyle has massive public health implications, making sleeping on the street even MORE unhealthy.

Electronic health information exchange improves public health disease reporting
Disease tracking is an important area of focus for health departments in the midst of the COVID-19 pandemic.

Pandemic likely to cause long-term health problems, Yale School of Public Health finds
The coronavirus pandemic's life-altering effects are likely to result in lasting physical and mental health consequences for many people--particularly those from vulnerable populations--a new study led by the Yale School of Public Health finds.

The Lancet Public Health: US modelling study estimates impact of school closures for COVID-19 on US health-care workforce and associated mortality
US policymakers considering physical distancing measures to slow the spread of COVID-19 face a difficult trade-off between closing schools to reduce transmission and new cases, and potential health-care worker absenteeism due to additional childcare needs that could ultimately increase mortality from COVID-19, according to new modelling research published in The Lancet Public Health journal.

The Lancet Public Health: Access to identification documents reflecting gender identity may improve trans mental health
Results from a survey of over 20,000 American trans adults suggest that having access to identification documents which reflect their identified gender helps to improve their mental health and may reduce suicidal thoughts, according to a study published in The Lancet Public Health journal.

The Lancet Public Health: Study estimates mental health impact of welfare reform, Universal Credit, in Great Britain
The 2013 Universal Credit welfare reform appears to have led to an increase in the prevalence of psychological distress among unemployed recipients, according to a nationally representative study following more than 52,000 working-age individuals from England, Wales, and Scotland over nine years between 2009-2018, published as part of an issue of The Lancet Public Health journal on income and health.

BU researchers: Pornography is not a 'public health crisis'
Researchers from the Boston University School of Public Health (BUSPH) have written an editorial in the American Journal of Public Health special February issue arguing against the claim that pornography is a public health crisis, and explaining why such a claim actually endangers the health of the public.

The Lancet Public Health: Ageism linked to poorer health in older people in England
Ageism may be linked with poorer health in older people in England, according to an observational study of over 7,500 people aged over 50 published in The Lancet Public Health journal.

Study: Public transportation use linked to better public health
Promoting robust public transportation systems may come with a bonus for public health -- lower obesity rates.

Read More: Public Health News and Public Health Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to