Table 3. Meta-analyses on influenza vaccines for the elderly.
| Gross1 | Vu14 | Jefferson3 | Osterholm9 | |
|---|---|---|---|---|
| |
|
|
|
|
| End date of the search (mm/yy) |
Not reported (published in 1995) |
12/2000 |
10/2009 |
02/2011 |
| Participant’s age-range (years) |
≥ 65 |
≥ 65 |
≥ 65 |
All ages § |
| Included study designs |
Obs. |
RCTs, Obs. |
RCTs, Obs. |
RCTs *, Obs. |
| Funding source |
Public institution |
NR |
Public institutions |
Not-for-profit foundation |
| |
|
|
|
|
|
Laboratory-confirmed cases |
|
|
|
|
| - Parenteral Inactivated |
|
|
|
|
| N. data sets (sample) |
NA |
NA |
RCTs: 3 (2217) Obs.: 10 (20,190) φ |
Obs.: 2 (395) § |
| Vaccine efficacy, % (95% CI) |
NA |
NA |
RCTs: 58 (34; 73) Obs.: 41 (-15; 70) φ |
Obs.: 63 (28; 81) § |
| |
|
|
|
|
|
Clinically-confirmed cases |
|
|
|
|
| - Parenteral Inactivated |
|
|
|
|
| N. data sets (sample) |
23 (9043) |
RCTs and Obs.: 3 (6271) Ω |
RCTs: 4 (6894) Obs.: 37 (46,239) φ |
NA |
| Vaccine efficacy, % (95% CI) |
56 (39; 68) |
RCTs and Obs: 35 (19; 47) Ω |
RCTs: 41 (27; 53) Obs.: 26 (13; 38) φ |
NA |
| |
|
|
|
|
|
Hospitalization for influenza or pneumonia |
|
|
|
|
| - Parenteral Inactivated |
|
|
|
|
| N. data sets (sample) |
9 (24,324) |
Obs.: 9 (> 446,336) Ω |
Obs.: 8 (949,215) β |
NA |
| Vaccine efficacy, % (95% CI) |
48 (28; 65) |
Obs.: 33 (27; 38) Ω |
Obs.: 27 (21; 33) β |
NA |
| |
|
|
|
|
|
Mortality for any cause |
|
|
|
|
| - Parenteral Inactivated |
|
|
|
|
| N. data sets (sample) |
30 (30,028) |
Obs.: 4 (163,087) Ω |
RCTs: 1 (699) Obs.: 7 (742,575) β |
NA |
| Vaccine efficacy, % (95% CI) |
68 (56; 76) |
Obs.: 50 (45; 56) Ω |
RCTs: -2 (-872; 89) Obs.: 47 (39; 54) β |
NA |
| |
|
|
|
|
|
Mild/moderate adverse events |
|
|
|
|
| - Local pain |
|
|
|
|
| N. data sets (sample) |
NA |
NA |
4 (2560) |
NA |
| Increase in Risk, % (95% CI) |
NA |
NA |
256 (161; 387) |
NA |
| |
|
|
|
|
| - Fever |
|
|
|
|
| N. data sets (sample) |
NA |
NA |
3 (2519) |
NA |
| Increase in Risk, % (95% CI) |
NA |
NA |
57 (-8; 171) |
NA |
| |
|
|
|
|
| -Systemic, any |
|
|
|
|
| N. data sets (sample) |
NA |
NA |
1 (672) |
NA |
| Increase in Risk, % (95% CI) |
NA |
NA |
75 (-26; 312) |
NA |
| |
|
|
|
|
|
Serious adverse events (Guillain-Barré syndrome) |
|
|
|
|
| N. data sets (sample) |
NA |
NA |
4 (> 100 millions) ** |
NA |
| Increase in Risk, % (95% CI) |
NA |
NA |
60 (-53; 444) |
NA |
RCT, Randomized clinical trial; Obs., Observational studies; CI, Confidence Interval; NA, Not assessed; NR, Not reported. * RCTs were searched but none was found including only elderly. Only two out of four studies reported outcome stratified by age, allowing data extraction for subjects aged 64 and over; the other two studies included subjects aged 18 and over, with no stratification. Ω Authors included solely the studies enrolling community-living elderly only; with samples larger than 30; in which the influenza vaccine strain matched the circulating strain. It was not possible to extract the total number of subjects enrolled in the studies evaluating hospitalizations. Cohort and case-control studies were pooled together. § Authors included only studies on vaccines licensed in USA, assessing RT-PCR or culture-confirmed influenza cases. Estimates on LAV from RCTs were re-elaborated from Table 3. All estimates reported in the table are referred to elderly only. φ Results have been re-elaborated combining studies on community-dwelling elderly (analysis 2.1) and elderly from nursing homes, with (analysis 1.1) or without (analysis 1.7) a clear definition of the outcome. Only meta-analyses on cohort studies have been used. β = Adjusted rates of community-dwellers only. ** Re-elaborated from Table 1; the samples were the entire USA population in different seasons plus 21 million subjects from another study.