Table 1.
Vaccinees and Placebo Recipients Enrolled in Phase 1 Clinical Trials of Seven Live-attenuated RSV Vaccines
| Vaccine | Study Years | Vaccinees |
Placebo Recipients |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Total (n) | Evaluable for VE* (n) | Infected with Vaccine Virus† [n (%)] | Any Antibody Response‡ [n (%)] | RSV PRNT Response§ [n (%)] | Total (n) | Evaluable for VE (n) | Evaluable for MAARI Rates‖ (n) | ||||
| Less promising¶ | |||||||||||
| ΔNS2/Δ1313/I1314L (105) | 2014–15 | 15 | 15 | 12 (80) | 10 (67) | 8 (53) | 7 | 7 | 6 | ||
| RSVcps2 | 2013–15 | 34 | 34 | 29 (85) | 23 (68) | 20 (59) | 16 | 16 | 14 | ||
| LID/cp/ΔM2-2 | 2016–17 | 11 | 11 | 6 (55) | 6 (55) | 5 (45) | 6 | 6 | 3 | ||
| Total, less promising | 2013–17 | 60 | 60 | 47 (78) | 39 (65) | 33 (55) | 29 | 29 | 23 | ||
| More promising** | |||||||||||
| MEDIΔM2-2 | 2011–14 | 20 | 20 | 20 (100) | 19 (95) | 19 (95) | 10 | 9 | 9 | ||
| ΔNS2/Δ1313/I1314L (106) | 2015–17 | 20 | 20 | 20 (100) | 19 (95) | 16 (80) | 10 | 10 | 10 | ||
| LIDΔM2-2 | 2014–15 | 20 | 20 | 19 (95) | 18 (90) | 18 (90) | 9 | 9 | 9 | ||
| LIDΔM2-2/1030s | 2016–17 | 20 | 20 | 20 (100) | 20 (100) | 17 (85) | 11 | 11 | 10 | ||
| D46/NS2/N/ΔM2-2-HindIII | 2017–18 | 21 | 20 | 20 (100) | 20 (100) | 19 (95) | 11 | 11 | 11 | ||
| Total, more promising | 2011–18 | 101 | 100 | 99 (99) | 96 (96) | 89 (89) | 51 | 50 | 49 | ||
| Total (all vaccines) | 2011–18 | 161†† | 160 | 146 | 135†† | 122 | 80 | 79 | 72 | ||
Definition of abbreviations: F = fusion; MAALRI = medically attended acute lower respiratory illness; MAARI = medically attended acute respiratory illness; PRNT = plaque reduction–neutralizing antibody titer; RSV = respiratory syncytial virus; VE = vaccine efficacy.
Evaluable for VE: vaccinees included in the analysis of VE.
Infected with vaccine virus: defined as detection of vaccine virus by culture or PCR and/or a greater than or equal to fourfold rise in serum RSV PRNT and/or a greater than or equal to fourfold rise in serum ELISA IgG antibody titer to the RSV F glycoprotein as measured by endpoint titration. Note that for consistency between all studies, ELISA IgG titers measured by endpoint titration were used for these analyses, whereas interpolated ELISA titers were previously reported for several studies (7–9, 17).
With any antibody response: greater than or equal to fourfold rise in RSV PRNT or RSV F IgG titers between Study Days 0 and 56.
With RSV PRNT response: greater than or equal to fourfold rise in RSV PRNT between Study Days 0 and 56.
Placebo recipients evaluable for serosurveillance: placebo recipients with surveillance serum specimens available who did not have a greater than or equal to fourfold rise in RSV PRNT between Days 0 and 56 and could therefore be included in analyses of background rates of MAARI and MAALRI.
“Less promising”: PRNT response ≤59%.
“More promising”: PRNT response ≥80%. Each of these definitions is described in more detail in the text.
Of 161 vaccinees, 1 was lost to follow-up; thus, data from 160 vaccinees in total and 135 vaccinees with any antibody response were evaluable for vaccine efficacy.