MESSAGE
| DATE | 2020-10-15 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [Hangout - NYLXS] COVID is NEVER going away ... now what?
|
https://medicalxpress.com/news/2020-10-covid-virus-endemic.html
medicalxpress.com
Will the COVID-19 virus become endemic?
by Columbia University's Mailman School of Public Health
6-8 minutes
SARS-CoV-2 , COVID-19
Colorized scanning electron micrograph of a dying cell (blue) heavily
infected with SARS-CoV-2 (yellow), the virus that causes COVID-19.
Credit: NIAID Integrated Research Facility, Fort Detrick, Maryland.
A new article by Columbia Mailman School researchers Jeffrey Shaman and
Marta Galanti explores the potential for the COVID-19 virus to become
endemic, a regular feature producing recurring outbreaks in humans. They
identify crucial contributing factors, including the risk for
reinfection, vaccine availability and efficacy, as well as potential
seasonality and interactions with other viral infections that may
modulate the transmission of the virus. The article appears in the
journal Science.
Shaman is a professor of environmental health sciences and director of
the Columbia Mailman School Climate and Health program and a leading
authority in modeling infectious disease outbreaks like SARS-CoV-2 and
influenza. He was among the first to recognize the importance of
asymptomatic spread and the effectiveness of lockdown measures and
published highly cited estimations of the hypothetic lives saved had
lockdown occurred sooner. He and Galanti, a post-doctoral research
scientist in Shaman's research group, also published research finding
reinfections with endemic coronaviruses are not uncommon, even within a
year of prior infection.
The new paper explores one potential scenario in which immunity to
SARS-CoV-2, either through infection or a vaccine, diminishes within a
year—a rate similar to that seen for the endemic betacoronavirus that
causes mild respiratory illness. The result would be yearly outbreaks of
COVID-19. On the other hand, if immunity to SARS-CoV-2 was longer,
perhaps through protection provided by immune response to infection with
other endemic coronaviruses, we might experience what would initially
appear to be an elimination of COVID-19 followed by a resurgence after a
few years. Other contributing factors include the availability and
effectiveness of a vaccine and the innate seasonality of the virus.
"Should reinfection prove commonplace, and barring a highly effective
vaccine delivered to most of the world's population, SARS-CoV-2 will
likely settle into a pattern of endemicity," the authors write. "Whether
reinfections will be commonplace, how often they will occur, how
contagious re-infected individuals will be, and whether the risk of
severe clinical outcomes changes with subsequent infection remain to be
understood."
Reinfection
Among those who have been infected with COVID-19, serological studies
indicate that most infections, regardless of severity, induce
development of some SARS-CoV-2-specific antibodies. Yet it remains
unclear whether those antibodies are themselves sufficient to provide
long-term 'sterilizing immunity' to prevent reinfection. For many
viruses, insufficient immune response, waning immunity, or mutations
that allow it to 'escape' immune detection can undermine or circumvent
immunity and allow subsequent reinfection, although a prior infection
may provide partial immunity and reduce symptom severity.
Co-Infection
Immune response to SARS-CoV-2 may be affected by whether or not someone
is currently or was recently infected with another virus. Many studies
prior to the pandemic show that infection with one virus can provide
short-term protection—about a week—against a second infection. Other
studies confirm that simultaneous respiratory virus infections are not
associated with increased disease severity. While some SARS-CoV-2
coinfections have been documented, including co-infections with
influenza and respiratory syncytial virus, there is insufficient data to
draw conclusions. At the population level, a significant seasonal
influenza outbreak could strain hospitals already dealing with COVID-19.
Seasonality
Evidence suggests COVID-19 could be more transmissible during winter.
Outside the tropics, many common respiratory viruses reemerge seasonally
during particular times of the year. The endemic coronaviruses (OC43,
HKU1, NL63, 229E) all exhibit seasonality in temperate regions similar
to influenza. Similarly, environmental conditions may also modulate
SARS-CoV-2 transmissibility—not enough to preclude transmission during
the early stages of the pandemic when immunity is generally low but
perhaps sufficient to favor recurring seasonal transmission during
winter in temperate regions, similar to influenza, once immunity increases.
More information: Jeffrey Shaman et al, Will SARS-CoV-2 become endemic?,
Science (2020). DOI: 10.1126/science.abe5960
Citation: Will the COVID-19 virus become endemic? (2020, October 15)
retrieved 15 October 2020 from
https://medicalxpress.com/news/2020-10-covid-virus-endemic.html
This document is subject to copyright. Apart from any fair dealing for
the purpose of private study or research, no part may be reproduced
without the written permission. The content is provided for information
purposes only.
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proportions in the mind of the world - RI Safir 1998
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