Table 2.
Risk of bias sensitivity analysis
| All datasets | Excluding studies with high risk of bias | ||||||||||||||
| Comparisons | Effect measure | Number of datasets | Effect estimate | LL 95% CI | UL 95% CI | Statistical significance | Number of datasets | Effect estimate* | LL 95% CI | UL 95% CI | Statistical significance | VE absolute change | Change effect measure direction | Change in statistical significance | |
| Analysis 1.1 | Influenza | Risk ratio | 7 | 0.20 | 0.13 | 0.32 | Sign | 5 | 0.23 | 0.12 | 0.49 | Sign | ‐3% | Unchanged | Unchanged |
| Analysis 1.1.1 | Under 2 years | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 1.1.2 | Under 6 years | Risk ratio | 6 | 0.18 | 0.11 | 0.29 | Sign | 4 | 0.20 | 0.10 | 0.42 | Sign | ‐2% | Unchanged | Unchanged |
| Analysis 1.1.3 | Over 6 years | Risk ratio | 1 | 0.47 | 0.23 | 0.97 | Sign | 1 | 0.47 | 0.23 | 0.97 | Sign | 0% | Unchanged | Unchanged |
| Analysis 1.2 | Influenza‐like illness | Risk ratio | 13 | 0.67 | 0.62 | 0.72 | Sign | 5 | 0.5 | 0.45 | 0.55 | Sign | 17% | Unchanged | Unchanged |
| Analysis 1.2.1 | Under 2 years | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 1.2.2 | Under 6 years | Risk ratio | 5 | 0.67 | 0.57 | 0.77 | Sign | 2 | 0.48 | 0.44 | 0.54 | Sign | 19% | Unchanged | Unchanged |
| Analysis 1.2.3 | Over 6 years | Risk ratio | 8 | 0.67 | 0.6 | 0.74 | Sign | 3 | 0.55 | 0.4 | 0.76 | Sign | 12% | Unchanged | Unchanged |
| Analysis 2.1 | Influenza | Risk ratio | 7 | 0.41 | 0.29 | 0.59 | Sign | 7 | 0.41 | 0.29 | 0.59 | Sign | 0% | Unchanged | Unchanged |
| Analysis 2.1.1 | Under 2 years | Risk ratio | 2 | 0.55 | 0.18 | 1.69 | No sign | 2 | 0.55 | 0.18 | 1.69 | No sign | 0% | Unchanged | Unchanged |
| Analysis 2.1.2 | Under 6 years | Risk ratio | 2 | 0.61 | 0.34 | 1.08 | No Sign | 2 | 0.61 | 0.34 | 1.08 | No Sign | 0% | Unchanged | Unchanged |
| Analysis 2.1.3 | Over 6 years | Risk ratio | 3 | 0.31 | 0.22 | 0.45 | Sign | 3 | 0.31 | 0.22 | 0.45 | Sign | 0% | Unchanged | Unchanged |
| Analysis 2.2 | Influenza‐like illness | Risk ratio | 7 | 0.64 | 0.54 | 0.76 | Sign | 4 | 0.39 | 0.19 | 0.8 | Sign | 25% | Unchanged | Unchanged |
| Analysis 2.2.1 | Under 2 years | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 2.2.2 | Under 6 years | Risk ratio | 3 | 0.39 | 0.21 | 0.69 | Sign | 2 | 0.52 | 0.14 | 1.98 | No sign | ‐13% | Unchanged | Changed |
| Analysis 2.2.3 | Over 6 years | Risk ratio | 4 | 0.72 | 0.66 | 0.78 | Sign | 2 | 0.24 | 0.08 | 0.7 | Sign | 48% | Unchanged | Unchanged |
| Analysis 3.1 | Influenza | Risk ratio | 1 | 0.56 | 0.35 | 0.91 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 3.1.1 | Under 2 years | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 3.1.2 | Under 6 years | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 3.1.3 | Over 6 years | Risk ratio | 1 | 0.56 | 0.35 | 0.91 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 3.2 | Influenza‐like illness | Risk ratio | 2 | 0.63 | 0.57 | 0.69 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 3.2.1 | Under 2 years | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 3.2.2 | Under 6 years | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 3.2.3 | Over 6 years | Risk ratio | 2 | 0.63 | 0.57 | 0.69 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.1 | Influenza | Risk ratio | 6 | 0.42 | 0.25 | 0.73 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.1.1 | Under 2 years | Risk ratio | 3 | 0.63 | 0.27 | 1.47 | No sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.1.2 | Under 6 years | Risk ratio | 1 | 0.34 | 0.13 | 0.89 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.1.3 | Over 6 years | Risk ratio | 2 | 0.36 | 0.12 | 1.11 | No sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.2 | Influenza‐like illness | Risk ratio | 13 | 0.53 | 0.42 | 0.67 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.2.1 | Under 2 years | Risk ratio | 1 | 0.47 | 0.23 | 0.93 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.2.2 | Under 6 years | Risk ratio | 5 | 0.74 | 0.59 | 0.93 | Sign | 1 | 0.98 | 0.94 | 1.03 | No sign | ‐24% | Unchanged | Changed |
| Analysis 4.2.3 | Over 6 years | Risk ratio | 7 | 0.44 | 0.29 | 0.68 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.3 | Otitis media | Risk ratio | 1 | 0.48 | 0.22 | 1.03 | No sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 4.3.1 | Children aged 6 months to 5 years | Risk ratio | 1 | 0.48 | 0.22 | 1.03 | No sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 5.1 | Influenza | Risk ratio | 7 | 0.19 | 0.11 | 0.32 | Sign | 5 | 0.21 | 0.09 | 0.48 | Sign | ‐2% | Unchanged | Unchanged |
| Analysis 5.1.1 | Live attenuated vaccines (1 dose) | Risk ratio | 5 | 0.23 | 0.12 | 0.47 | Sign | 3 | 0.38 | 0.2 | 0.75 | Sign | ‐11% | Unchanged | Unchanged |
| Analysis 5.1.2 | Live attenuated vaccines (2 doses) | Risk ratio | 2 | 0.11 | 0.04 | 0.26 | Sign | 2 | 0.11 | 0.04 | 0.26 | Sign | 0% | Unchanged | Unchanged |
| Analysis 5.2 | Influenza‐like illness | Risk ratio | 8 | 0.69 | 0.6 | 0.8 | Sign | 3 | 0.53 | 0.39 | 0.74 | Sign | 16% | Unchanged | Unchanged |
| Analysis 5.2.1 | Live attenuated vaccines (1 dose) | Risk ratio | 2 | 0.64 | 0.18 | 2.22 | No sign | 1 | 0.27 | 0.06 | 1.16 | No sign | 37% | Unchanged | Unchanged |
| Analysis 5.2.2 | Live attenuated vaccines (2 doses) | Risk ratio | 6 | 0.66 | 0.57 | 0.76 | Sign | 2 | 0.55 | 0.39 | 0.79 | Sign | 11% | Unchanged | Unchanged |
| Analysis 5.3 | Otitis media (all episodes) | Risk ratio | 2 | 0.98 | 0.95 | 1.01 | No sign | 1 | 0.98 | 0.95 | 1.01 | No sign | 0% | Unchanged | Unchanged |
| Analysis 5.4 | Working days lost (number of events, parents) | Risk ratio | 2 | 0.69 | 0.46 | 1.03 | No sign | 2 | 0.69 | 0.46 | 1.03 | No sign | 0% | Unchanged | Unchanged |
| Analysis 5.5 | Drug prescriptions (number of events) | Risk ratio | 1 | 0.99 | 0.87 | 1.12 | No sign | 1 | 0.99 | 0.87 | 1.12 | No sign | 0% | Unchanged | Unchanged |
| Analysis 5.6 | Outpatients attendance for pneumonia and influenza | Risk ratio | 2 | 0.76 | 0.59 | 0.98 | Sign | 2 | 0.76 | 0.59 | 0.98 | Sign | 0% | Unchanged | Unchanged |
| Analysis 6.1 | Influenza | Risk ratio | 5 | 0.36 | 0.28 | 0.48 | Sign | 5 | 0.36 | 0.28 | 0.48 | Sign | 0% | Unchanged | Unchanged |
| Analysis 6.1.1 | Inactivated vaccines (1 dose) | Risk ratio | 5 | 0.36 | 0.28 | 0.48 | Sign | 5 | 0.36 | 0.28 | 0.48 | Sign | 0% | Unchanged | Unchanged |
| Analysis 6.1.2 | Inactivated vaccines ( 2 doses) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 6.2 | Influenza‐like illness | Risk ratio | 4 | 0.72 | 0.65 | 0.79 | Sign | 2 | 0.35 | 0.15 | 0.81 | Sign | 37% | Unchanged | Unchanged |
| Analysis 6.2.1 | Inactivated vaccines (1 dose) | Risk ratio | 2 | 0.35 | 0.15 | 0.81 | Sign | 2 | 0.35 | 0.15 | 0.81 | Sign | 0% | Unchanged | Unchanged |
| Analysis 6.2.2 | Inactivated vaccines (2 doses) | Risk ratio | 2 | 0.72 | 0.69 | 0.76 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | changed | |
| Analysis 7.1 | Influenza vs ILI (crude data) | Odds Ratio | ‐‐ | ‐‐ | Unchanged | Unchanged | |||||||||
| Analysis 7.1.1 | Children aged below 6 years | Odds Ratio | 9 | 0.59 | 0.45 | 0.77 | Sign | 6 | 0.55 | 0.44 | 0.7 | Sign | 4% | Unchanged | Unchanged |
| Analysis 7.1.2 | Children aged 5 to 19 years | Odds Ratio | 1 | 0.76 | 0.07 | 8.66 | No sign | 1 | 0.76 | 0.07 | 8.66 | No sign | 0% | Unchanged | Unchanged |
| Analysis 7.2 | Influenza vs ILI (adj. estimates) | Odds Ratio | ‐‐ | ‐‐ | Unchanged | Unchanged | |||||||||
| Analysis 7.2.1 | Children aged below 23 months to fully vaccinated | Odds Ratio | 7 | 0.6 | 0.39 | 0.94 | Sign | 4 | 0.46 | 0.29 | 0.73 | Sign | 14% | Unchanged | Unchanged |
| Analysis 7.2.2 | Children aged 24 to 59 months to fully vaccinated | Odds Ratio | 4 | 0.4 | 0.22 | 0.7 | Sign | 4 | 0.4 | 0.22 | 0.7 | Sign | 0% | Unchanged | Unchanged |
| Analysis 7.2.3 | Children aged 6 to 59 months to fully vaccinated | Odds Ratio | 5 | 0.45 | 0.32 | 0.62 | Sign | 5 | 0.45 | 0.32 | 0.62 | Sign | 0% | Unchanged | Unchanged |
| Analysis 7.2.4 | Children aged below 14 years old to fully vaccinated | Odds Ratio | 1 | 0.23 | 0.06 | 0.84 | Sign | 1 | 0.23 | 0.06 | 0.84 | Sign | 0% | Unchanged | Unchanged |
| Analysis 7.3 | Influenza‐like illness vs no symptoms | Odds Ratio | 2 | 0.49 | 0.28 | 0.86 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 7.3.1 | Inactivated vaccine (1 dose) | Odds Ratio | 1 | 0.53 | 0.26 | 1.07 | No sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 7.3.2 | Inactivated vaccine (2 doses) | Odds Ratio | 1 | 0.44 | 0.18 | 1.1 | No sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 8.1 | Influenza | Risk ratio | 11 | 0.27 | 0.18 | 0.42 | Sign | 11 | 0.27 | 0.18 | 0.42 | Sign | 0% | Unchanged | Unchanged |
| Analysis 8.1.1 | Live attenuated vaccines (1 dose) | Risk ratio | 4 | 0.27 | 0.12 | 0.61 | Sign | 4 | 0.27 | 0.12 | 0.61 | Sign | 0% | Unchanged | Unchanged |
| Analysis 8.1.2 | Live attenuated vaccines (2 doses) | Risk ratio | 2 | 0.11 | 0.04 | 0.26 | Sign | 2 | 0.11 | 0.04 | 0.26 | Sign | 0% | Unchanged | Unchanged |
| Analysis 8.1.3 | Inactivated vaccines (1 dose) | Risk ratio | 5 | 0.36 | 0.28 | 0.48 | Sign | 5 | 0.36 | 0.28 | 0.48 | Sign | 0% | Unchanged | Unchanged |
| Analysis 8.1.4 | Inactivated vaccines (2 doses) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 8.2 | Influenza‐like illness | Risk ratio | 12 | 0.69 | 0.62 | 0.77 | Sign | 5 | 0.5 | 0.38 | 0.67 | Sign | 19% | Unchanged | Unchanged |
| Analysis 8.2.1 | Live attenuated vaccines (1 dose) | Risk ratio | 2 | 0.64 | 0.18 | 2.22 | No sign | 1 | 0.27 | 0.06 | 1.16 | No sign | 37% | Unchanged | Unchanged |
| Analysis 8.2.2 | Live attenuated vaccines (2 doses) | Risk ratio | 6 | 0.66 | 0.57 | 0.76 | Sign | 2 | 0.55 | 0.39 | 0.79 | Sign | 11% | Unchanged | Unchanged |
| Analysis 8.2.3 | Inactivated vaccines (1 dose) | Risk ratio | 2 | 0.35 | 0.15 | 0.81 | Sign | 2 | 0.35 | 0.15 | 0.81 | Sign | 0% | Unchanged | Unchanged |
| Analysis 8.2.4 | Inactivated vaccines (2 doses) | Risk ratio | 2 | 0.72 | 0.69 | 0.76 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 8.3 | Secondary cases | Risk ratio | 1 | 1.68 | 0.56 | 4.99 | No sign | 1 | 1.68 | 0.56 | 4.99 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.3.1 | Live attenuated vaccines (1 dose) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 8.3.2 | Live attenuated vaccines (2 doses) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 8.3.3 | Inactivated vaccines (1 dose) | Risk ratio | 1 | 1.68 | 0.56 | 4.99 | No sign | 1 | 1.68 | 0.56 | 4.99 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.3.4 | Inactivated vaccines (2 doses) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 8.4 | School absenteeism | Risk ratio | 2 | 0.49 | 0.26 | 0.92 | Sign | 2 | 0.49 | 0.26 | 0.92 | Sign | 0% | Unchanged | Unchanged |
| Analysis 8.4.1 | Live attenuated vaccines (1 dose) | Risk ratio | 1 | 0.51 | 0.22 | 1.19 | No sign | 1 | 0.51 | 0.22 | 1.19 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.4.2 | Live attenuated vaccines (2 doses) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 8.4.3 | Inactivated vaccines (1 dose) | Risk ratio | 1 | 0.46 | 0.17 | 1.22 | No sign | 1 | 0.46 | 0.17 | 1.22 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.4.4 | Inactivated vaccines (2 doses) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 8.5 | Lower respiratory tract disease | Risk ratio | 3 | 0.2 | 0.03 | 1.54 | No sign | 2 | 0.52 | 0.08 | 3.37 | No sign | ‐32% | Unchanged | Unchanged |
| Analysis 8.5.1 | Live attenuated vaccines (1 dose) | Risk ratio | 2 | 0.16 | 0.01 | 4.45 | No sign | 1 | 0.73 | 0.07 | 7.88 | No sign | ‐57% | Unchanged | Unchanged |
| Analysis 8.5.2 | Live attenuated vaccines (2 doses) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 8.5.3 | Inactivated vaccines (1 dose) | Risk ratio | 1 | 0.3 | 0.01 | 6.17 | No sign | 1 | 0.3 | 0.01 | 6.17 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.5.4 | Inactivated vaccines (2 doses) | Risk ratio | 0 | 0 | 0 | 0 | ‐‐ | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Unchanged | |
| Analysis 8.6 | Acute otitis media | Risk ratio | 7 | 1 | 0.79 | 1.26 | No sign | 5 | 1.03 | 0.91 | 1.17 | No sign | ‐3% | changed | Unchanged |
| Analysis 8.6.1 | Live attenuated vaccines (1 dose) | Risk ratio | 3 | 0.42 | 0.05 | 3.79 | No sign | 1 | 1.46 | 0.09 | 22.93 | No sign | ‐104% | changed | Unchanged |
| Analysis 8.6.2 | Live attenuated vaccines (2 doses) | Risk ratio | 1 | 0.98 | 0.95 | 1.01 | No sign | 1 | 0.98 | 0.95 | 1.01 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.6.3 | Inactivated vaccines (1 dose) | Risk ratio | 1 | 1.52 | 0.1 | 23.76 | No sign | 1 | 1.52 | 0.1 | 23.76 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.6.4 | Inactivated vaccines (2 doses) | Risk ratio | 2 | 1.15 | 0.95 | 1.4 | No sign | 2 | 1.15 | 0.95 | 1.4 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.7 | Hospitalisation due to acute otitis media | Risk ratio | ‐‐ | ‐‐ | Unchanged | Unchanged | |||||||||
| Analysis 8.7.1 | Inactivated vaccine (2 doses) | Risk ratio | 2 | 1.41 | 0.62 | 3.24 | No sign | 2 | 1.41 | 0.62 | 3.24 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.8 | Consequences of acute otitis media | Mean Difference | ‐‐ | ‐‐ | Unchanged | Unchanged | |||||||||
| Analysis 8.8.1 | Inactivated vaccine, 2 doses visits | Mean Difference | 2 | ‐0.02 | ‐0.27 | 0.23 | No sign | 2 | ‐0.02 | ‐0.27 | 0.23 | No sign | Unchanged | Unchanged | |
| Analysis 8.8.2 | Inactivated vaccine (2 doses; courses of antibiotics | Mean Difference | 2 | 0.13 | ‐0.36 | 0.63 | No sign | 2 | 0.13 | ‐0.36 | 0.63 | No sign | Unchanged | Unchanged | |
| Analysis 8.9 | Outpatients attendance for pneumonia and influenza | Risk ratio | 2 | 0.76 | 0.59 | 0.98 | Sign | 1 | 0.85 | 0.75 | 0.96 | Sign | ‐9% | Unchanged | Unchanged |
| Analysis 8.9.1 | Live attenuated vaccine (1 dose) | Risk ratio | 1 | 0.65 | 0.49 | 0.85 | Sign | 0 | 0 | 0 | 0 | ‐‐ | Unchanged | Changed | |
| Analysis 8.9.2 | Live attenuated vaccine (2 doses) | Risk ratio | 1 | 0.85 | 0.75 | 0.96 | Sign | 1 | 0.85 | 0.75 | 0.96 | Sign | 0% | Unchanged | Unchanged |
| Analysis 8.10 | Working days lost (number of events, parents of children 6 to 36 months of age) | Risk ratio | 2 | 0.69 | 0.46 | 1.03 | No sign | 1 | 0.83 | 0.71 | 0.98 | Sign | ‐14% | Unchanged | Changed |
| Analysis 8.10.1 | Live attenuated vaccine | Risk ratio | 2 | 0.69 | 0.46 | 1.03 | No sign | 1 | 0.83 | 0.71 | 0.98 | Sign | ‐14% | Unchanged | Changed |
| Analysis 8.11 | Drug prescriptions (number of events, 6 to 36 months of age) | Risk ratio | 1 | 0.99 | 0.87 | 1.12 | No sign | 1 | 0.99 | 0.87 | 1.12 | No sign | 0% | Unchanged | Unchanged |
| Analysis 8.11.1 | Live attenuated vaccine | Risk ratio | 1 | 0.99 | 0.87 | 1.12 | No sign | 1 | 0.99 | 0.87 | 1.12 | No sign | 0% | Unchanged | Unchanged |
CI: confidence interval LL: lower limit No sign: when effect measure is not statistically significant risk ratio*: effect estimate excluding high risk of bias datasets Sign: when effect measure is statistically significant UL: upper limit VE absolute change = (1‐RR*)‐(1‐RR)