Gaps in early surveillance of coronavirus led to record-breaking US
trajectory

Date:
August 21, 2020
Source:
University of Notre Dame
Summary:
New research provides insight into how limited testing and gaps
in surveillance during the initial phase of the COVID-19 epidemic
resulted in so many cases going undetected.



FULL STORY ==========================================================================
As the United States exceeds 5 million reported coronavirus cases --
the world's first country to do so -- epidemiologists have pinpointed
what helped to set the country on this path.


========================================================================== Research from the University of Notre Dame estimates that more than
100,000 people were already infected with COVID-19 by early March -- when
only 1,514 cases and 39 deaths had been officially reported and before
a national emergency was declared. The study provides insight into how
limited testing and gaps in surveillance during the initial phase of
the epidemic resulted in so many cases going undetected. The study was published in the Proceedings of the National Academy of Sciences.

"We weren't testing enough," said Alex Perkins, associate professor in
the Department of Biological Sciences, an expert in infectious disease epidemiology and population biology and the lead of the study. "The
number of unobserved infections appears to be due to very low rates
of case detection during a critical time, when the epidemic was really
starting to take hold in this country. Part of it was the availability
of testing, but another huge part was case definitions and the fact that
they were overly restrictive early on." According to the Centers for
Disease Control and Prevention, the first confirmed case of COVID-19 in
the United States was reported in January. Early guidance on identifying possible infection included respiratory symptoms, and travel to Wuhan,
China -- where an outbreak occurred in December 2019.

"While we were focusing on people coming back from China, we were ignoring people coming from Europe, and actually quite a bit of the initial seeding
of the virus into various parts of the United States came from Italy,"
Perkins said.

While awareness and concern over COVID-19 grew from January to March,
it wasn't until Feb. 29 that Washington became the first state to
declare a state of emergency -- closing schools and restaurants and
imposing restrictions on large gatherings. By mid-March several states followed, but a lack of a coordinated national response created a number
of variables as each state decided for itself how to react to a rising
number of cases.



==========================================================================
By focusing their analysis on the January to March timeframe, when little
to no action had been taken on a wide scale, Perkins and his team were
able to incorporate a constant into their models. While other studies
provide a sense of how school closures and lockdowns slowed the spread
of the virus, looking at transmission for the first three months of the
year gave the epidemiologists a clearer picture of how the virus emerged
and spread throughout the country so quickly.

"It was such a crucial period in terms of how this situation started,"
said Perkins. "We look at the United States now and compare it to
other countries like South Korea or Germany, New Zealand or Vietnam,
any number of countries who have done a much, much better job controlling transmission. The key differences really come down to the time period we examine in this study. Those countries had adequate surveillance up and
running at that time, whereas we show that throughout most of February
the United States missed the vast majority of infections that were already
out there. This particular timeframe that we focus on is really important
for figuring out how we got here in the first place." The study used a simulation model beginning on Jan. 1, using data reported by Johns Hopkins University on confirmed cases and deaths, accounting for asymptomatic infections, case fatality rates and local transmission. Perkins and his
team first generated an estimate of total infections in the U.S.

through March 12. The team then factored in how detection of symptomatic infections changed over time and estimated the number of unobserved
infections during this time.

A significant aspect of the analysis is the model's incorporation of many uncertainties that played out in the early days of the epidemic in the
U.S., which Perkins said speaks to the inherent nature of a novel and
emerging infectious disease. The number of unobserved and unreported
infections also speaks to how critical containment strategies are when
battling infectious diseases.

"I think the fact that there were so many infections by the second half
of February speaks to the importance of and what we could have done in
terms of containment," said Perkins. "If you think about Ebola or SARS
(severe acute respiratory syndrome) or other emerging infectious diseases, there have been cases that show up in the U.S. or other countries where officials move quickly to get ahead of them. They isolate those people,
they do contact tracing -- and transmission is extinguished. I think a
lot of us were hoping that would be the situation with this disease. By
the time we got to February, the problem had grown so big, containing
the virus wasn't possible." The potential for misdiagnosis and the
limitations of surveillance are huge issues across infectious diseases, especially emerging infectious diseases, he added. As illustrated in
the COVID-19 study, while public health officials must work quickly
to understand how a new virus functions, without appropriate testing
or coordinated response strategies the risk grows for infections to
go unreported.

Perkins is an affiliated member of Notre Dame's Eck Institute for Global
Health and Environmental Change Initiative. Co-leads of the study include
Sean M.

Cavany and Sean M. Moore, and co-authors include Anita Lerch, Rachel
J. Oidtman and Marya Poterek, all at Notre Dame.

The study originally appeared prior to peer review on medRxiv, a preprint server for health sciences research.

The study was supported by the National Science Foundation through a
Rapid Response Research (RAPID) grant.


========================================================================== Story Source: Materials provided by University_of_Notre_Dame. Original
written by Jessica Sieff. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. T. Alex Perkins, Sean M. Cavany, Sean M. Moore, Rachel J. Oidtman,
Anita
Lerch, Marya Poterek. Estimating unobserved SARS-CoV-2 infections in
the United States. Proceedings of the National Academy of Sciences,
Aug. 21, 2020; DOI: 10.1073/pnas.2005476117 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200821155737.htm

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