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 0.898587620 0.671862160 2.1992597402
sex_cd1 0.483134812 0.483212314 -0.0001550932
sex_cd2 0.516865188 0.516787686 0.0001550932
age_cd10 0.076304352 0.049425001 0.1012464192
age_cd11 0.081650174 0.041485318 0.1466775278
age_cd12 0.084493036 0.032602172 0.1865733535
age_cd13 0.083953599 0.023462210 0.2181298788
age_cd14 0.077582355 0.016733619 0.2274606522
age_cd15 0.068527387 0.012156880 0.2231181058
age_cd16 0.048165034 0.008215423 0.1865803011
age_cd17 0.033497790 0.007253037 0.1458589159
age_cd18 0.035282995 0.012237980 0.1249091665
age_cd2 0.004668464 0.177498013 -2.5354036348
age_cd3 0.027991198 0.173313257 -0.8810198701
age_cd4 0.056131740 0.080021302 -0.1037882622
age_cd5 0.060601486 0.064433895 -0.0160622132
age_cd6 0.059790696 0.076882735 -0.0720882998
age_cd7 0.065551910 0.086130830 -0.0831480991
age_cd8 0.066085635 0.075231000 -0.0368123851
age_cd9 0.069722149 0.062917327 0.0267192980
residence_area_cdBE100 0.192021950 0.271165730 -0.2009285148
residence_area_cdBE310 0.095597215 0.088169142 0.0252622841
residence_area_cdBE323 0.056235792 0.053790881 0.0106126766
residence_area_cdBE328 0.049718876 0.030474651 0.0885347426
residence_area_cdBE329 0.031642401 0.030972064 0.0038294871
residence_area_cdBE32A 0.031318820 0.020256060 0.0635141327
residence_area_cdBE32B 0.083749167 0.090726493 -0.0251878781
residence_area_cdBE32C 0.025567807 0.021975378 0.0227596552
residence_area_cdBE32D 0.021892937 0.018036625 0.0263528162
residence_area_cdBE331 0.027770444 0.022426834 0.0325206280
residence_area_cdBE332 0.133410509 0.124469471 0.0262957873
residence_area_cdBE334 0.021567316 0.014911574 0.0458176653
residence_area_cdBE335 0.046504691 0.050609060 -0.0194912089
residence_area_cdBE336 0.013598161 0.013624788 -0.0002299111
residence_area_cdBE341 0.007965074 0.007212487 0.0084663934
residence_area_cdBE342 0.009119847 0.009045346 0.0007837180
residence_area_cdBE343 0.013446368 0.011443200 0.0173921956
residence_area_cdBE344 0.014289393 0.013908638 0.0032082133
residence_area_cdBE345 0.009831073 0.009596825 0.0023742138
residence_area_cdBE351 0.026499378 0.022813411 0.0229490948
residence_area_cdBE352 0.072678448 0.061608915 0.0426394233
residence_area_cdBE353 0.015574332 0.012762426 0.0227093472
essential_worker_blTRUE 0.052656813 0.028028136 0.1102706999
institutionalized_blTRUE 0.007390136 0.002565461 0.0563316624
socecon_lvl_cdhigh 0.279732436 0.184907843 0.2112528812
socecon_lvl_cdlow 0.422423562 0.542847797 -0.2438007833
socecon_lvl_cdmiddle 0.297844003 0.272244359 0.0559786835
comorbidities_blTRUE 0.238453192 0.081797391 0.3676178677
immunestatus_blTRUE 0.026491217 0.011024184 0.0963132700
Means intervention group Means control group Standardized mean difference
distance 5.000004e-01 0.4999995791 1.828475e-03
sex_cd1 4.800436e-01 0.4799955541 9.615221e-05
sex_cd2 5.199564e-01 0.5200044459 -9.615221e-05
age_cd10 8.121684e-02 0.0812361538 -7.068662e-05
age_cd11 8.809991e-02 0.0882289500 -4.552732e-04
age_cd12 9.225329e-02 0.0923206401 -2.327264e-04
age_cd13 9.217606e-02 0.0922782538 -3.532912e-04
age_cd14 8.540226e-02 0.0854253323 -8.257133e-05
age_cd15 7.526298e-02 0.0752502675 4.819998e-05
age_cd16 5.243938e-02 0.0524026434 1.647955e-04
age_cd17 3.624923e-02 0.0361988350 2.696093e-04
age_cd18 3.828895e-02 0.0382531573 1.865252e-04
age_cd2 1.648356e-05 0.0000160126 1.160008e-04
age_cd3 5.145696e-03 0.0051310961 2.040529e-04
age_cd4 3.815991e-02 0.0381316499 1.474956e-04
age_cd5 5.582275e-02 0.0557935467 1.271869e-04
age_cd6 5.691631e-02 0.0568809906 1.524582e-04
age_cd7 6.379655e-02 0.0637475699 2.004161e-04
age_cd8 6.646500e-02 0.0664518153 5.293941e-05
age_cd9 7.228841e-02 0.0722530857 1.363965e-04
residence_area_cdBE100 1.782965e-01 0.1783191292 -5.906023e-05
residence_area_cdBE310 9.713101e-02 0.0971385485 -2.544553e-05
residence_area_cdBE323 5.599653e-02 0.0559946461 8.193615e-06
residence_area_cdBE328 5.166606e-02 0.0516670058 -4.255294e-06
residence_area_cdBE329 3.199647e-02 0.0320007083 -2.408440e-05
residence_area_cdBE32A 3.162865e-02 0.0316229994 3.229259e-05
residence_area_cdBE32B 8.365170e-02 0.0836611207 -3.402086e-05
residence_area_cdBE32C 2.609300e-02 0.0260887625 2.658916e-05
residence_area_cdBE32D 2.278452e-02 0.0227788641 3.787469e-05
residence_area_cdBE331 2.868610e-02 0.0286861003 0.000000e+00
residence_area_cdBE332 1.355514e-01 0.1355532447 -5.503277e-06
residence_area_cdBE334 2.270539e-02 0.0227002140 3.477750e-05
residence_area_cdBE335 4.619211e-02 0.0461982322 -2.916835e-05
residence_area_cdBE336 1.410898e-02 0.0141056869 2.795237e-05
residence_area_cdBE341 8.194212e-03 0.0081932702 1.044831e-05
residence_area_cdBE342 9.246805e-03 0.0092444502 2.460222e-05
residence_area_cdBE343 1.392343e-02 0.0139210711 2.009669e-05
residence_area_cdBE344 1.470239e-02 0.0146962693 5.086846e-05
residence_area_cdBE345 1.013786e-02 0.0101345623 3.290944e-05
residence_area_cdBE351 2.735376e-02 0.0273490483 2.887334e-05
residence_area_cdBE352 7.371541e-02 0.0737111742 1.622087e-05
residence_area_cdBE353 1.623772e-02 0.0162348916 2.235767e-05
essential_worker_blTRUE 5.550108e-02 0.0554869526 6.170960e-05
institutionalized_blTRUE 8.270978e-03 0.0081376970 1.471616e-03
socecon_lvl_cdhigh 2.921065e-01 0.2920236534 1.822808e-04
socecon_lvl_cdlow 4.048079e-01 0.4049068255 -2.014880e-04
socecon_lvl_cdmiddle 3.030855e-01 0.3030695211 3.484091e-05
comorbidities_blTRUE 2.585630e-01 0.2585676824 -1.075629e-05
immunestatus_blTRUE 2.858579e-02 0.0284821752 6.217679e-04

Propensity score distribution