Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unpacking the Drop in COVID-19 Case Fatality Rates: A Study of National
  and Florida Line-Level Data   Since the COVID-19 pandemic first reached the United States, the case
fatality rate has fallen precipitously. Several possible explanations have been
floated, including greater detection of mild cases due to expanded testing,
shifts in age distribution among the infected, lags between confirmed cases and
reported deaths, improvements in treatment, mutations in the virus, and
decreased viral load as a result of mask-wearing. Using both Florida line-level
data and recently released (but incomplete) national line level data from April
1, 2020 to November 1, 2020 on cases, hospitalizations, and deaths--each
stratified by age--we unpack the drop in case fatality rate (CFR). Under the
hypothesis that improvements in treatment efficacy should correspond to
decreases in hospitalization fatality rate (HFR), we find that improvements in
the national data do not always match the story told by Florida data. In the
national data, treatment improvements between the first wave and the second
wave appear substantial, but modest when compared to the drop in aggregate CFR.
By contrast, possibly due to constrained resources in a much larger second
peak, Florida data suggests comparatively little difference between the first
and second wave, with HFR slightly increasing in every age group. However, by
November 1st, both Florida and national data suggest significant decreases in
age-stratified HFR since April 1st. By accounting for several confounding
factors, our analysis shows how age-stratified HFR can provide a more realistic
picture of treatment improvements than CFR. One key limitation of our analysis
is that the national line-level data remains incomplete and plagued by
artifacts. Our analysis highlights the crucial role that this data can play but
also the pressing need for public, complete, and high-quality age-stratified
line-level data for both cases, hospitalizations, and deaths for all states.

26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an