Focus on COVID-19 deaths in under-65s for better insights into infection
rates

Date:
November 2, 2020
Source:
University of Cambridge
Summary:
Simply comparing the total number of deaths across countries
may provide a misleading representation of the underlying level
of transmission of SARS-CoV-2, the virus that causes COVID-19,
because of large differences in reported COVID-19 death rates in
elderly populations in different countries.



FULL STORY ========================================================================== Simply comparing the total number of deaths across countries may provide
a misleading representation of the underlying level of transmission of SARS-CoV- 2, the virus that causes COVID-19, because of large differences
in reported COVID-19 death rates in elderly populations in different
countries.


==========================================================================
The research, conducted by scientists at the University of Cambridge
and the Institut Pasteur, was published today in the leading journal
Nature. It highlights how large COVID-19 outbreaks in European nursing
homes, and the potential for missing deaths in some Asian and South
American countries, have skewed COVID-19 death data for older age
groups, rendering cross-country comparisons of the scale of the pandemic inaccurate.

The researchers say that reporting of deaths from COVID-19 among those
under the age of 65 is likely to be far more reliable, and can therefore
give clearer insights into the underlying transmission of the virus
and enable better comparisons between countries -- crucial in guiding government strategies to try to get COVID-19 under control.

"Simply comparing the total number of deaths across countries can be
misleading as a representation of the underlying level of transmission
of SARS-CoV-2. Most deaths are in older people, but they are the least comparable across countries," said Megan O'Driscoll, a PhD researcher
in the University of Cambridge's Department of Genetics and first author
of the paper.

In countries including the UK, Canada and Sweden, the COVID-19 pandemic
has disproportionately affected nursing home residents, who account
for over 20% of all reported COVID-19 deaths. The level of SARS-CoV-2 transmission among the general population can be difficult to disentangle
from these large outbreaks.

By contrast, some countries in Asia and South America have far fewer
reported COVID-19 deaths in older people than expected. One potential explanation for these 'missing deaths' is that causes of deaths in
elderly populations may be less likely to be investigated and reported
as countries struggle to contain the epidemic.



========================================================================== "Nursing homes are enclosed communities of people, and once the virus gets
in it can spread quickly resulting in higher levels of infection than
in the general population. We're seeing an excessively large number of
deaths from COVID-19 in this older age group, particularly in countries
that have many nursing homes," said Dr Henrik Salje in the University
of Cambridge's Department of Genetics, the senior author of the report.

He added: "It's not just that residents are older than the general
population, they are also generally more frail, so a 70-year old living in
a nursing home is often more likely to die of COVID-19 than a 70-year old
in the general population. To reduce the overall number of COVID-19 deaths
it is vital to protect vulnerable elderly communities." In their new
model, the researchers integrated age-specific COVID-19 death data from
45 countries with 22 national-level seroprevalence surveys. Governments of
many countries are using seroprevalence surveys to estimate the number of people in a population with antibodies against the coronavirus. Antibodies indicate if a person has been infected with SARS-CoV-2 at some point,
so are a good indicator of population-wide infection rates.

"Our model shows that the number of COVID-19 deaths by age, in people
under 65 years old, is highly consistent across countries and likely to be
a reliable indicator of the number of infections in the population. This
is of critical use in a context where most infections are unobserved,"
said O'Driscoll.

The model can be used at a country-wide level to predict a person's
likelihood of dying from COVID-19 following infection, depending on their
age. It also works in reverse, to estimate a country's total number of infections given its number of COVID-19 deaths in an age group, which
is particularly useful in places where seroprevalence studies have not
been conducted.



========================================================================== Using death data from under-65 age groups only, which is most
representative of transmission in the whole population, it shows that
by the 1 September this year an average of 5% of the population of a
country had been infected with SARS-CoV-2. However, in some places it
was much higher, especially South America.

For example, using Peru's COVID-19 death figures, which equate to 0.01%
of the country's population, the model suggests that over half of the population of Peru has now been infected with SARS-CoV-2 -- a figure
far higher than expected. This indicates particularly high rates of transmission of the virus in Peru.

But even after excluding data from the over 65's, the model shows that
COVID-19 death rates cannot be compared between some countries, because
the relationship between infections and deaths is not consistent when
other widespread 'co- morbidity' factors are involved.

"It seems that people living in places such as Slovenia and Denmark
have a low probability of death following infection with SARS-CoV-2,
even after accounting for the ages of their populations, which is very different to what we've seen in New York, for example. There are likely
to be fundamental differences in the populations across countries,
which might include their underlying health," said Salje.

The model also revealed a strong pattern across countries in the 5-9
year age group, which consistently has the lowest probability of death following SARS- CoV-2 infection.

The work demonstrates how age-specific death data alone can be used to reconstruct the underlying level of SARS-CoV-2 infection in a country and
how it has changed over time. The researchers say this approach could be applied at sub-national scale, and may be of particular use in settings
where large seroprevalence studies might not be feasible.

This research was funded by the University of Cambridge COVID-19 Rapid
Response Grant.


========================================================================== Story Source: Materials provided by University_of_Cambridge. The original
story is licensed under a Creative_Commons_License. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Megan O'Driscoll, Gabriel Ribeiro Dos Santos, Lin Wang, Derek A. T.

Cummings, Andrew S. Azman, Juliette Paireau, Arnaud Fontanet,
Simon Cauchemez, Henrik Salje. Age-specific mortality and immunity
patterns of SARS-CoV-2. Nature, 2020; DOI: 10.1038/s41586-020-2918-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/11/201102110015.htm

--- up 10 weeks, 7 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)