diff --git a/template.qmd b/template.qmd
index 8e3b6c3..c2e2fdf 100644
--- a/template.qmd
+++ b/template.qmd
@@ -77,7 +77,6 @@ stats <- append(
 )
 correlation <- stats[["r2"]]
 sub_rate <- stats[["sub_rate"]]
-sub_rate <- display.num(sub_rate, 2)
 p_value_lm <- stats[["pvalue"]]
 
 # NV counts
@@ -262,7 +261,7 @@ frequency-weighted distances.](`r params$tree`){#fig-tree}
 To estimate the evolutionary rate, root-to-tip distances measured on the previous
 tree (@fig-tree) have been correlated with time, obtaining a $R^2$ of
 $`r display.num(correlation, 4)`$ and a p-value of $`r p_value_lm`$. The estimated evolutionary
-rate is $`r sub_rate`$ number of changes per year (@fig-tempest).
+rate is $`r display.num(sub_rate, 2)`$ changes per year (@fig-tempest).
 
 ![Scatterplot depicting the relationship between root-to-tip
 distances and the number of days passed since the first sample. The solid
diff --git a/workflow/core.smk b/workflow/core.smk
index 2bfe396..38ff64e 100644
--- a/workflow/core.smk
+++ b/workflow/core.smk
@@ -17,5 +17,6 @@ include: "rules/fetch.smk"
 include: "rules/fasta.smk"
 include: "rules/asr.smk"
 include: "rules/vaf.smk"
+include: "rules/sites.smk"
 include: "rules/distances.smk"
 include: "rules/evolution.smk"
diff --git a/workflow/rules/distances.smk b/workflow/rules/distances.smk
index 11fae38..77a4ae9 100644
--- a/workflow/rules/distances.smk
+++ b/workflow/rules/distances.smk
@@ -8,7 +8,7 @@ rule extract_afwdist_variants:
         mask_class = ["mask"],
     input:
         variants = OUTDIR/f"{OUTPUT_NAME}.variants.tsv",
-        mask_vcf = lambda wildcards: select_problematic_vcf(),
+        mask_vcf = OUTDIR / "all_mask_sites.vcf",
         ancestor = OUTDIR/f"{OUTPUT_NAME}.ancestor.fasta",
         reference = OUTDIR/"reference.fasta",
     output:
diff --git a/workflow/rules/sites.smk b/workflow/rules/sites.smk
new file mode 100644
index 0000000..493d06c
--- /dev/null
+++ b/workflow/rules/sites.smk
@@ -0,0 +1,123 @@
+rule bcftools_mpileup_all_sites:
+    threads: 1
+    conda: "../envs/var_calling.yaml"
+    params:
+        min_mq = 0,
+        min_bq = config["VC"]["MIN_QUALITY"],
+        mpileup_extra = "--no-BAQ"
+    input:
+        bam = get_input_bam,
+        reference = OUTDIR/"vaf"/"{sample}.reference.fasta",
+    output:
+        mpileup = temp(OUTDIR / "all_sites" / "{sample}.mpileup.vcf"),
+        query = temp(OUTDIR / "all_sites" / "{sample}.query.tsv"),
+    log:
+        mpileup = LOGDIR / "bcftools_mpileup_all_sites" / "{sample}.mpileup.txt",
+        query = LOGDIR / "bcftools_mpileup_all_sites" / "{sample}.query.txt",
+    shell:
+        "bcftools mpileup {params.mpileup_extra} -a AD,ADF,ADR --fasta-ref {input.reference:q} --threads {threads} -Q {params.min_bq} -q {params.min_mq} -Ov -o {output.mpileup:q} {input.bam:q} >{log.mpileup:q} 2>&1 && "
+        "echo 'CHROM\tPOS\tREF\tALT\tDP\tAD\tADF\tADR' >{output.query:q} && "
+        "bcftools query -f '%CHROM\t%POS\t%REF\t%ALT\t%DP\t[ %AD]\t[ %ADF]\t[ %ADR]\n' {output.mpileup:q} >>{output.query:q} 2>{log.query:q}"
+
+
+rule filter_mpileup_all_sites:
+    threads: 1
+    params:
+        min_total_AD = config["VC"]["MIN_DEPTH"],
+        min_total_ADF = 0,
+        min_total_ADR = 0,
+    input:
+        OUTDIR / "all_sites" / "{sample}.query.tsv",
+    output:
+        sites_pass = temp(OUTDIR / "all_sites" / "{sample}.filtered_sites.tsv"),
+        sites_fail = temp(OUTDIR / "all_sites" / "{sample}.fail_sites.tsv"),
+    log:
+        LOGDIR / "filter_mpileup_all_sites" / "{sample}.txt"
+    run:
+        import pandas as pd
+        df = pd.read_csv(input[0], sep="\t")
+        df["SAMPLE"] = wildcards.sample
+        df["REF_AD"] = df.AD.str.split(",").apply(lambda values: int(values[0]))
+        df["TOTAL_AD"] = df.AD.str.split(",").apply(lambda values: sum(int(n) for n in values))
+        df["TOTAL_ADF"] = df.ADF.str.split(",").apply(lambda values: sum(int(n) for n in values))
+        df["TOTAL_ADR"] = df.ADR.str.split(",").apply(lambda values: sum(int(n) for n in values))
+        mask = (
+            (df.TOTAL_AD >= params.min_total_AD) &
+            (df.TOTAL_ADF >= params.min_total_ADF) &
+            (df.TOTAL_ADR >= params.min_total_ADR)
+        )
+        df[mask].to_csv(output.sites_pass, sep="\t", index=False)
+        df[~mask].to_csv(output.sites_fail, sep="\t", index=False)
+
+
+use rule concat_vcf_fields as merge_filtered_mpileup_all_sites with:
+    input:
+        expand(OUTDIR / "all_sites" / "{sample}.filtered_sites.tsv", sample=iter_samples()),
+    output:
+        OUTDIR / f"{OUTPUT_NAME}.filtered_sites.tsv",
+
+
+use rule concat_vcf_fields as merge_fail_mpileup_all_sites with:
+    input:
+        expand(OUTDIR / "all_sites" / "{sample}.fail_sites.tsv", sample=iter_samples()),
+    output:
+        OUTDIR / f"{OUTPUT_NAME}.fail_sites.tsv",
+
+
+rule fill_all_sites:
+    conda: "../envs/renv.yaml"
+    input:
+        variants = OUTDIR/f"{OUTPUT_NAME}.variants.tsv",
+        sites = OUTDIR / f"{OUTPUT_NAME}.filtered_sites.tsv",
+    output:
+        variants = OUTDIR/f"{OUTPUT_NAME}.variants.all_sites.tsv",
+    log:
+        LOGDIR / "fill_all_sites" / "log.txt"
+    script:
+        "../scripts/fill_all_sites.R"
+
+
+rule compile_fail_sites_vcf:
+    params:
+        filter_text = "mask",
+        sub_text = "NA",
+        exc_text = "site_qual",
+    input:
+        sites = OUTDIR / f"{OUTPUT_NAME}.fail_sites.tsv",
+    output:
+        sites = temp(OUTDIR / f"{OUTPUT_NAME}.fail_sites.vcf"),
+    run:
+        import pandas as pd
+        HEADER = ["#CHROM", "POS", "ID", "REF", "ALT", "QUAL", "FILTER", "INFO"]
+        sites = (
+            pd.read_table(input.sites, sep="\t")
+                .drop_duplicates(subset=("CHROM", "POS", "REF"))
+                .rename(columns={"CHROM": "#CHROM"})
+        )
+        sites["ID"] = "."
+        sites["ALT"] = "."
+        sites["QUAL"] = "."
+        sites["FILTER"] = params.filter_text
+        sites["INFO"] = f"SUB={params.sub_text};EXC={params.exc_text}"
+        sites[HEADER].to_csv(output.sites, sep="\t", index=False)
+
+
+rule merge_mask_sites_vcf:
+    input:
+        lambda wildcards: select_problematic_vcf(),
+        OUTDIR / f"{OUTPUT_NAME}.fail_sites.vcf",
+    output:
+        sites = temp(OUTDIR / "all_mask_sites.vcf"),
+    run:
+        import pandas as pd
+        HEADER = ["#CHROM", "POS", "ID", "REF", "ALT", "QUAL", "FILTER", "INFO"]
+        (
+            pd.concat(
+                [pd.read_table(path, sep="\t", comment="#", names=HEADER, dtype={"POS": "int64"}) for path in input],
+                axis="rows",
+                ignore_index=True
+            )
+            .drop_duplicates(subset=("#CHROM", "POS", "FILTER"), keep="first")
+            .sort_values(by=["#CHROM", "POS"])
+            .to_csv(output.sites, sep="\t", index=False)
+        )
diff --git a/workflow/rules/vaf.smk b/workflow/rules/vaf.smk
index c42d580..b517ad9 100644
--- a/workflow/rules/vaf.smk
+++ b/workflow/rules/vaf.smk
@@ -204,72 +204,3 @@ use rule concat_vcf_fields as concat_variants with:
         expand(OUTDIR/"vaf"/"{sample}.variants.tsv", sample=iter_samples()),
     output:
         OUTDIR/f"{OUTPUT_NAME}.variants.tsv",
-
-
-rule bcftools_mpileup_all_sites:
-    threads: 1
-    conda: "../envs/var_calling.yaml"
-    params:
-        min_mq = 0,
-        min_bq = config["VC"]["MIN_QUALITY"],
-        mpileup_extra = "--no-BAQ"
-    input:
-        bam = get_input_bam,
-        reference = OUTDIR/"vaf"/"{sample}.reference.fasta",
-    output:
-        mpileup = temp(OUTDIR / "all_sites" / "{sample}.mpileup.vcf"),
-        query = temp(OUTDIR / "all_sites" / "{sample}.query.tsv"),
-    log:
-        mpileup = LOGDIR / "bcftools_mpileup_all_sites" / "{sample}.mpileup.txt",
-        query = LOGDIR / "bcftools_mpileup_all_sites" / "{sample}.query.txt",
-    shell:
-        "bcftools mpileup {params.mpileup_extra} -a AD,ADF,ADR --fasta-ref {input.reference:q} --threads {threads} -Q {params.min_bq} -q {params.min_mq} -Ov -o {output.mpileup:q} {input.bam:q} >{log.mpileup:q} 2>&1 && "
-        "echo 'CHROM\tPOS\tREF\tALT\tDP\tAD\tADF\tADR' >{output.query:q} && "
-        "bcftools query -f '%CHROM\t%POS\t%REF\t%ALT\t%DP\t[ %AD]\t[ %ADF]\t[ %ADR]\n' {output.mpileup:q} >>{output.query:q} 2>{log.query:q}"
-
-
-rule filter_mpileup_all_sites:
-    threads: 1
-    params:
-        min_total_AD = config["VC"]["MIN_DEPTH"],
-        min_total_ADF = 0,
-        min_total_ADR = 0,
-    input:
-        OUTDIR / "all_sites" / "{sample}.query.tsv",
-    output:
-        temp(OUTDIR / "all_sites" / "{sample}.filtered_sites.tsv"),
-    log:
-        LOGDIR / "filter_mpileup_all_sites" / "{sample}.txt"
-    run:
-        import pandas as pd
-        df = pd.read_csv(input[0], sep="\t")
-        df["SAMPLE"] = wildcards.sample
-        df["REF_AD"] = df.AD.str.split(",").apply(lambda values: int(values[0]))
-        df["TOTAL_AD"] = df.AD.str.split(",").apply(lambda values: sum(int(n) for n in values))
-        df["TOTAL_ADF"] = df.ADF.str.split(",").apply(lambda values: sum(int(n) for n in values))
-        df["TOTAL_ADR"] = df.ADR.str.split(",").apply(lambda values: sum(int(n) for n in values))
-        df[
-            (df.TOTAL_AD >= params.min_total_AD) &
-            (df.TOTAL_ADF >= params.min_total_ADF) &
-            (df.TOTAL_ADR >= params.min_total_ADR)
-        ].to_csv(output[0], sep="\t", index=False)
-
-
-use rule concat_vcf_fields as merge_filtered_mpileup_all_sites with:
-    input:
-        expand(OUTDIR / "all_sites" / "{sample}.filtered_sites.tsv", sample=iter_samples()),
-    output:
-        OUTDIR / f"{OUTPUT_NAME}.filtered_sites.tsv",
-
-
-rule fill_all_sites:
-    conda: "../envs/renv.yaml"
-    input:
-        variants = OUTDIR/f"{OUTPUT_NAME}.variants.tsv",
-        sites = OUTDIR / f"{OUTPUT_NAME}.filtered_sites.tsv",
-    output:
-        variants = OUTDIR/f"{OUTPUT_NAME}.variants.all_sites.tsv",
-    log:
-        LOGDIR / "fill_all_sites" / "log.txt"
-    script:
-        "../scripts/fill_all_sites.R"
diff --git a/workflow/scripts/calculate_dnds.R b/workflow/scripts/calculate_dnds.R
index f545c27..a0495cb 100644
--- a/workflow/scripts/calculate_dnds.R
+++ b/workflow/scripts/calculate_dnds.R
@@ -29,9 +29,11 @@ variants <- read_delim(
 log_info("Reading metadata table")
 metadata <- read_delim(snakemake@input[["metadata"]]) %>%
   mutate(
-    interval = as.numeric(
-      as.Date(CollectionDate) - min(as.Date(CollectionDate))
-    )
+    interval = difftime(
+      as.Date(CollectionDate),
+      min(as.Date(CollectionDate)),
+      units = "days"
+    ) |> as.numeric()
   ) %>%
   select(ID, interval) %>%
   rename(SAMPLE = ID)
diff --git a/workflow/scripts/report/time_signal_data.R b/workflow/scripts/report/time_signal_data.R
index d209528..04448b2 100644
--- a/workflow/scripts/report/time_signal_data.R
+++ b/workflow/scripts/report/time_signal_data.R
@@ -44,9 +44,11 @@ time.signal <- distRoot(
     by = "ID"
   ) %>%
   mutate(
-    date_interval = as.numeric(
-      as.Date(CollectionDate) - min(as.Date(CollectionDate))
-    )
+    date_interval = difftime(
+      as.Date(CollectionDate),
+      min(as.Date(CollectionDate)),
+      units = "days"
+    ) |> as.numeric()
   )
 
 # Save table