Will the COVID-19 virus become endemic?

Date:
October 15, 2020
Source:
Columbia University's Mailman School of Public Health
Summary:
A new article explores the potential for the COVID-19 virus to
become endemic, a regular feature producing recurring outbreaks
in humans.



FULL STORY ==========================================================================
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.


========================================================================== Story Source: Materials provided by Columbia_University's_Mailman_School_of_Public_Health.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jeffrey Shaman, Marta Galanti. Will SARS-CoV-2 become
endemic? Science,
2020; eabe5960 DOI: 10.1126/science.abe5960 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201015101820.htm

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