BY-COVID - WP5 - Baseline Use Case: COVID-19 vaccine effectiveness assessment

Matching cases to controls (1:1) and assessing covariate balance after matching

A sequence of nested (daily) trials are emulated with increasing time (t1, t2, …, tn), iterating over the days in the enrollment period. At each eligible time during the enrollment period, the vaccination status of eligible individuals is assessed and every individual who has completed a primary vaccination schedule at that time (coded here as initiation of the intervention strategy when emulating a nested target trial) is matched to an individual who has not (yet) completed the primary vaccination schedule (coded here as the control strategy when emulating a nested target trial). Newly vaccinated individuals (completing a primary vaccination schedule) are eligible for inclusion in the study, even if they had previously been selected in the “no (or partial) vaccine group”. Vaccinations have been administered in the context of national public health programs, without interference/manipulation of the research subjects.

We assess the covariate balance, which is the extent to which the distribution of covariates is similar across the intervention groups.

Standardized Mean Differences

The Standardized Mean Difference (SMD) represents a standardized difference in mean between contrasted intervention groups for each covariate.

Means intervention group Means control group Standardized mean difference
distance 0.85440681 0.65296607 1.9020165178
sex_cd1 0.48267366 0.54192113 -0.1185661440
sex_cd2 0.51732634 0.45807887 0.1185661440
age_cd10 0.06363036 0.03771330 0.1061768421
age_cd11 0.07401716 0.03673087 0.1424234383
age_cd12 0.07906398 0.03388985 0.1674116536
age_cd13 0.07915523 0.03225963 0.1736996983
age_cd14 0.08069844 0.03187186 0.1792646857
age_cd15 0.07998784 0.03105223 0.1803915762
age_cd16 0.04802431 0.02185199 0.1224049084
age_cd17 0.03496399 0.02394007 0.0600141517
age_cd18 0.02769991 0.04564057 -0.1093198767
age_cd2 0.01293252 0.25070149 -2.1044574284
age_cd3 0.05299425 0.07574089 -0.1015375309
age_cd4 0.05390677 0.05540155 -0.0066189695
age_cd5 0.05429522 0.06420837 -0.0437475031
age_cd6 0.06185927 0.07585847 -0.0581121245
age_cd7 0.06230620 0.07097571 -0.0358672901
age_cd8 0.06687130 0.06290374 0.0158830199
age_cd9 0.06759325 0.04925939 0.0730296968
residence_area_cdFI193 0.05200183 0.05096423 0.0046732194
residence_area_cdFI194 0.03537992 0.04292956 -0.0408667432
residence_area_cdFI195 0.03280092 0.03288142 -0.0004519568
residence_area_cdFI196 0.04062436 0.04294426 -0.0117511613
residence_area_cdFI197 0.10043602 0.09523799 0.0172933014
residence_area_cdFI1B1 0.28088508 0.30051032 -0.0436668134
residence_area_cdFI1C1 0.09097811 0.07822805 0.0443360061
residence_area_cdFI1C2 0.03275278 0.03085552 0.0106594329
residence_area_cdFI1C3 0.03844466 0.04160571 -0.0164409409
residence_area_cdFI1C4 0.02889702 0.02628705 0.0155803032
residence_area_cdFI1C5 0.02318320 0.01749606 0.0377920931
residence_area_cdFI1D1 0.02638004 0.02244778 0.0245363444
residence_area_cdFI1D2 0.04929150 0.04104723 0.0380839970
residence_area_cdFI1D3 0.03224031 0.02802467 0.0238659883
residence_area_cdFI1D5 0.01266557 0.01367940 -0.0090660344
residence_area_cdFI1D7 0.03366000 0.03329859 0.0020039128
residence_area_cdFI1D8 0.01395419 0.01310396 0.0072482953
residence_area_cdFI1D9 0.07542450 0.08845821 -0.0493560583
essential_worker_blTRUE 0.09025138 0.04679484 0.1516587655
socecon_lvl_cd1 0.14938923 0.11305173 0.1019365723
socecon_lvl_cd2 0.24982046 0.26105827 -0.0259588197
socecon_lvl_cd3 0.60079031 0.62589001 -0.0512514925
comorbidities_blTRUE 0.33917167 0.21915183 0.2535122393
immunestatus_blTRUE 0.17251345 0.09728085 0.1991196427
Means intervention group Means control group Standardized mean difference
distance 0.5000001014 4.999999e-01 4.034454e-03
sex_cd1 0.4673633611 4.673549e-01 1.703579e-05
sex_cd2 0.5326366389 5.326451e-01 -1.703579e-05
age_cd10 0.0756074022 7.561513e-02 -2.922819e-05
age_cd11 0.0950613487 9.507139e-02 -3.424871e-05
age_cd12 0.1046610192 1.046742e-01 -4.291163e-05
age_cd13 0.1084665795 1.084786e-01 -3.851477e-05
age_cd14 0.1145790432 1.145493e-01 9.339973e-05
age_cd15 0.1162391947 1.162280e-01 3.495720e-05
age_cd16 0.0692724001 6.927240e-02 0.000000e+00
age_cd17 0.0484156120 4.841561e-02 0.000000e+00
age_cd18 0.0360515980 3.605160e-02 0.000000e+00
age_cd2 0.0000000000 3.863513e-07 -8.790352e-04
age_cd3 0.0008661996 8.661996e-04 0.000000e+00
age_cd4 0.0146318961 1.463074e-02 9.652817e-06
age_cd5 0.0213207960 2.131925e-02 1.069844e-05
age_cd6 0.0306480888 3.064848e-02 -2.241506e-06
age_cd7 0.0386022892 3.860036e-02 1.002754e-05
age_cd8 0.0542101086 5.421281e-02 -1.194381e-05
age_cd9 0.0713664241 7.136565e-02 3.001534e-06
residence_area_cdFI193 0.0477364064 4.773563e-02 3.624173e-06
residence_area_cdFI194 0.0335449508 3.354341e-02 8.582977e-06
residence_area_cdFI195 0.0322209249 3.221977e-02 6.563667e-06
residence_area_cdFI196 0.0409339192 4.093392e-02 0.000000e+00
residence_area_cdFI197 0.0930940479 9.309521e-02 -3.988977e-06
residence_area_cdFI1B1 0.3024052686 3.024095e-01 -9.252919e-06
residence_area_cdFI1C1 0.0884269244 8.842770e-02 -2.721600e-06
residence_area_cdFI1C2 0.0325462327 3.254662e-02 -2.177293e-06
residence_area_cdFI1C3 0.0414238127 4.142343e-02 1.938849e-06
residence_area_cdFI1C4 0.0303324398 3.033244e-02 0.000000e+00
residence_area_cdFI1C5 0.0251425829 2.514451e-02 -1.233891e-05
residence_area_cdFI1D1 0.0284223191 2.842077e-02 9.299805e-06
residence_area_cdFI1D2 0.0440115936 4.401159e-02 0.000000e+00
residence_area_cdFI1D3 0.0303258719 3.032626e-02 -2.253008e-06
residence_area_cdFI1D5 0.0132908708 1.328855e-02 2.024242e-05
residence_area_cdFI1D7 0.0316916237 3.169162e-02 0.000000e+00
residence_area_cdFI1D8 0.0131224216 1.312165e-02 6.790062e-06
residence_area_cdFI1D9 0.0713277889 7.132740e-02 1.501142e-06
essential_worker_blTRUE 0.0855822198 8.556329e-02 6.767283e-05
socecon_lvl_cd1 0.1454913963 1.454678e-01 6.683983e-05
socecon_lvl_cd2 0.2204980223 2.205104e-01 -2.982094e-05
socecon_lvl_cd3 0.6340105814 6.340218e-01 -2.325936e-05
comorbidities_blTRUE 0.4284921714 4.284833e-01 1.795675e-05
immunestatus_blTRUE 0.2224382784 2.224174e-01 5.016536e-05

Propensity score distribution