Skip to content

Commit

Permalink
Port historical foresite vignettes
Browse files Browse the repository at this point in the history
  • Loading branch information
pwinskill committed Nov 20, 2024
1 parent 8513d08 commit f47e30d
Show file tree
Hide file tree
Showing 9 changed files with 861 additions and 1 deletion.
5 changes: 4 additions & 1 deletion DESCRIPTION
Original file line number Diff line number Diff line change
Expand Up @@ -27,4 +27,7 @@ Imports:
withr
Suggests:
testthat (>= 3.0.0),
fs
fs,
rmarkdown,
knitr
VignetteBuilder: knitr
276 changes: 276 additions & 0 deletions vignettes/Interventions.Rmd
Original file line number Diff line number Diff line change
@@ -0,0 +1,276 @@
---
title: "Interventions"
output: rmarkdown::html_vignette
bibliography: references.bib
csl: nature.csl
link-citations: true
vignette: >
%\VignetteIndexEntry{Interventions}
%\VignetteEngine{knitr::rmarkdown}
%\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>"
)
```


`site_file$interventions`


Interventions contains the historical intervention information for a site. It is
also the section of the site file that you would modify with intervention
information for future scenarios. Details, references and methods for individual
interventions are shown below:

## ITNs

### ITN use

`site_file$interventions$itn_use`

Due to differences in the availability of data sources the approach for countries
within sub-Saharan Africa differs to countries outside of sub-Saharan Africa:

#### Within sub-Saharan Africa

The population at risk weighted mean ITN use estimates for each site are taken
from the malaria atlas project raster entitled:
"Insecticide treated bednet (ITN) use version 2020". This, and other elements
of the [netz R package](https://mrc-ide.github.io/netz/) are based on work by
Bertozzi-Villa *et al* @bertozzi

#### Outside of sub-Saharan Africa

ITN use is much more heterogeneous outside of SSA and data are less systematically
collected. As a result, there are strong assumptions associated with the historical
scale and magnitude of ITN distributions. We make the assumption that any reported
ITN distributions (as detailed by the world malaria report @WMR) are tarted to areas
that have > 1% PfPr or > 1% PvPr at baseline. Annual distributions in these regions
are then scaled so that that number of ITNs distributed is aligned with the
world malaria report.

### Missing years

Available data on ITN use (via MAP @MAP or the world malaria report @ WMR) will not extend
to the present year. Missing ITN use estimates to present are filled assuming a
constant, continuing level of coverage. To respect the multi-year cyclical
nature of ITN distribution cycles any missing estimates are filled in assuming
that coverage is constant with respect to 3 years prior. For example if years
2019, 2020 and 2021 are missing then 2019 == 2016, 2020 == 2017 and 2021 == 2018.

### Net type

`site_file$interventions$net_type`

It is assumed that all nets distributed prior to 2025 are standard pyrethroid
(`pyrethroid_only`) bed nets. Current available net types are: pyrethroid_only,
pyrethroid_pbo and pyrethroid_pyrrole.

### Net input distribution

`site_file$interventions$itn_input_dist`

We need to estimate the annual ITN distributions that would cumulatively result
in our observed timeseries of ITN usage. For the we use the `fit_usage()`
function from the [netz R package](https://mrc-ide.github.io/netz/).
We an impose 3 year cyclical limits to the number of nets that are
distributed to avoid unrealistic over-distribution.

### Pyrethroid resistance

`site_file$interventions$pyrethroid_resistance`

For each site we include an estimated level of pyrethroid insecticide resistance.
This has been estimated by Tom Churcher and colleagues using spatio-temporally
distributed bioassay mortality data. This work is not yet published. Therefore
for attribution/citation and further information on the methods used please contact
Pete Winskill or Tom Churcher.

### ITN efficacy parameters

`site_file$interventions$dn0`
`site_file$interventions$rn0`
`site_file$interventions$gamman`
`site_file$interventions$rnm`

Given an ITN type and level of pyrethroid insecticide resistance, we can link to the
corresponding estimates of the key ITN efficacy parameters. These have been
estimated by Ellie Sherrard-Smith *et al* @sherrard2022.
Please note that gamman is provided in units of years here, these will need to be converted to days for use in
malariasimulaiton.

## IRS

### IRS coverage

`site_file$interventions$irs_cov`

As with ITNs, due to differences in the availability of data sources the approach
for countries within sub-Saharan Africa differs to countries outside of
sub-Saharan Africa:

#### Within sub-Saharan Africa

The population at risk weighted mean IRS coverage estimates for each site are
taken from the malaria atlas project raster entitled:
"Indoor Residual Spraying (IRS) coverage version 2020" @MAP. Coverage estimates
are rescaled such that the country-level estimate of the number of persons protected
by IRS matches the number reported in the world malaria report @WMR.

#### Outside of sub-Saharan Africa

IRS coverage is much more heterogeneous outside of SSA and data are less systematically
collected. As a result, there are strong assumptions associated with the historical
scale and magnitude of IRS campaigns. We make the assumption that any reported
IRS campaigns (as detailed by the world malaria report @WMR) are tarted to areas
that have > 1% PfPr or > 1% PvPr at baseline. Coverage in these regions
are then scaled so that that number of persons protected by IRS is aligned with the
world malaria report.

### IRS insecticide

`site_file$interventions$irs_insecticide`

It is assumed that a DDT-type insecticide is used prior to 2017, after which
there is a switch to an actellic-like insecticide.

Current available IRS insecticide options are: ddt, actellic, bendiocarb,
sumishield.

### Number of rounds of IRS per year

`site_file$interventions$irs_spray_rounds`

We assume a single IRS spray round per year.

### IRS efficacy parameters

`site_file$interventions$ls_theta`
`site_file$interventions$ls_gamma`
`site_file$interventions$ks_theta`
`site_file$interventions$ks_gamma`
`site_file$interventions$ms_theta`
`site_file$interventions$ms_gamma`

Given an IRS insecticide type we can link to the
corresponding estimates of the key IRS efficacy parameters. These have been
estimated by Ellie Sherrard-Smith *et al* @sherrard2018.

### IRS households sprayed

It is often helpful to convert the number of persons protected by IRS into an
estimate of the number of households covered. To aid this conversion we have
included country-levels estimates of the average household size obtained from
the UN @UNHH.

`site_file$interventions$hh_size`

### Missing years

Available data on IRS coverage (via MAP @MAP or the world malaria report @WMR) will not extend
to the present year. Missing IRS coverage estimates to present are filled assuming a
constant, continuing level of coverage.

## Treatment

### Coverage

`site_file$interventions$tx_cov`

The population at risk weighted mean treatment coverage of an effective
antimalarial for each site are taken from the malaria atlas project raster entitled:
"Effective treatment with an Antimalarial drug version 2020" @MAP.

### Drug type

`site_file$interventions$prop_act`

We estimate the proportion of treatments that are with an ACT from
DHS StatCompiler data @DHS, using the indicator:
"Children who took any ACT" (ID: ML_AMLD_C_ACT).
For SSA estimates by year are expanded by linear interpolation between data
points and an assumption of constant coverage after the most recent data point.
We assume that ACT coverage is zero before 2006, when the WHO recommendation was
first issued. For outside of SSA the DHS indicator is confounded by treatment
for Plasmodium vivax, and we therefore assume the mean values by year from data
within SSA.

### Drug provider

`site_file$interventions$prop_public`

We include an estimate of the proportion of treatments that are from the public
sector `prop_public`. This is useful for costing.
We use the DHS StatCompiler @DHS
indicator "Children with fever for whom advice or treatment was sought,
the source was a public sector facility" (ID: ML_FEVA_C_PUB). We assume a
constant proportion over time by country, estimated as the mean from all
country survey estimates since 2010. For countries without survey data, we
assume the median across all estimates.

## Seasonal malaria chemoprevention (SMC)

### SMC coverage

`site_file$interventions$smc_cov`

Historical SMC implementation and coverage estimates are fragmented. We
identify historical SMC implementation areas from maps presented by both
Access SMC @access_SMC and more recently
SMC alliance @SMC_alliance. We assume a linear increase in
coverage post implementation initiation up to a maximum of 80% to capture an
increasing number of smaller sub-national units being targeted over time.

### SMC drug

`site_file$interventions$smc_drug`

We assume that SP-AQ is used for SMC. This is currently the only available drug
option.

### Number of SMC rounds delivered annualy

`site_file$interventions$smc_n_rounds`

We assumed that historical SMC is delivered over 4 rounds `smc_n_rounds`.

### SMC age range

`site_file$interventions$smc_min_age`
`site_file$interventions$smc_max_age`

We assume SMC is delivered to children aged between 3 months and 5 years.

## RTS,S vaccine

`site_file$interventions$rtss_cov`

We include historical RTS,S coverage that has occurred as part of the MVIP
implementation trial, sub-nationally in Malawi, Ghana and Kenya. The spatial
distribution is informed from an
MVIP briefing presentation @MVIP

## Perennial malaria chemoprevention (PMC).

This intervention has been known in the past as intermittent preventative treatment
of infants (IPTi).

### PMC coverage

`site_file$interventions$pmc_cov`

Due to the very limited (non-trial setting) implementation of PMC historically,
we assume 0 coverage.

### PMC drug

`site_file$interventions$pmc_drug`

We assume PMC would be implemented with SP. This is currently the only available
drug option.

## Citations
50 changes: 50 additions & 0 deletions vignettes/Metadata.Rmd
Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
---
title: "Metadata"
output: rmarkdown::html_vignette
bibliography: references.bib
csl: nature.csl
link-citations: true
vignette: >
%\VignetteIndexEntry{Metadata}
%\VignetteEngine{knitr::rmarkdown}
%\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>"
)
```

## Country

`site_file$country`

The ISO3c code identifying the country. The R package `countrycode` @countrycode
is useful for converting between ISO3c and country names.

## Version

`site_file$version`

The year and version of the site file.

## Admininstrative level

`site_file$admin_level`

The administrative level (e.g. state, region, province) of the sites within the site file.

## Sites

`site_file$sites`

The sites within the site file. These are the named sites disaggregated to the
specified administrative level. Further disaggregation may include, for example,
an [urban rural split](https://mrc-ide.github.io/site/articles/pop_demog.html).
We use the GADM @GADM
version 4.04 administrative boundary simple feature spatial files at the first
or second administrative unit level.

## Citations
30 changes: 30 additions & 0 deletions vignettes/Seasonality.Rmd
Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
---
title: "Seasonality"
output: rmarkdown::html_vignette
bibliography: references.bib
csl: nature.csl
link-citations: true
vignette: >
%\VignetteIndexEntry{Seasonality}
%\VignetteEngine{knitr::rmarkdown}
%\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>"
)
```

## Seasonality

`site_file$seasonality`

Daily rainfall global rasters for the period 2019-2021 were obtained from
CHIRPS @CHIRPS using the
[umbrella R package](https://mrc-ide.github.io/umbrella/). For each site we
estimate the fourier series parameters representing general seasonal profiles.
Please see the umbrella website for more information.

## Citations
Loading

0 comments on commit f47e30d

Please sign in to comment.