Challenges in clinical development of Group B Streptococcus vaccine, which likely be of greatest benefit to low-income Countries.

1. Shabir A Madhi
University of Witwatersrand
MRC: Respiratory and Meningeal Pathogens Research Unit,
DST/NRF SARCHI Chair: Vaccine Preventable Diseases

2. Overview
● Burden of neonatal morbidity and mortality.
● Epidemiology of invasive GBS disease.
● Immunology of invasive GBS disease.
● Current status of vaccine development.
• Conclusions.

3. Under-5 Mortality in South Asia and sub-
Saharan Africa
Liu L. et al. Lancet 2014; S0140-67361(14)61698-6
Deaths in 2013: 2,015,256 Deaths in 2013: 2,015,256

4. Overview
● Burden of neonatal morbidity and mortality.
● Epidemiology of invasive GBS disease.
● Immunology of invasive GBS disease.
● Current status of vaccine development.
• Conclusions.

5. Intrapartum Antibiotic Prophylaxis (IAP) for the
Prevention of Perinatal Invasive Group B Streptococcal
Disease; USA.
Schrag, S. J. and Verani, J. R. Vaccine: 2013; 31S: D20-D26
Risk-Based and
Screening-based
IAP Strategy

6. Bacterial Causes of Meningitis in 2003-2007 in
Pediatric Age-Groups.
Thigpen M.C et al. New Eng J Med; 2011; 364: 21:

7. Invasive Group B Streptococcal Disease in USA and
South Africa.
Schrag, S. J. and Verani, J. R. Vaccine 2013; D20-D26; 1Haffejee IE J Infect 1991; 22:225-31; 2Madhi SA et al,
Annals Trop Pediatr; 2003; 23; 15-23; 3Cutland C et al. Pediatrics 2012; 130: e581-90
2.00
2.062
1.02
0.63
2.032.061
0.561

8. Incidence (per 1 000 live births) of Invasive GBS Disease
in Low and Middle Income Countries.
Dagnew AF et al. Clinical Infectious Diseases; 2012: 55: 91-102

9. Timing of Early Onset Invasive GBS Disease In
South Africa and USA
Madhi SA et al. Vaccine; 2013; 315: D52-D57; Schuchat A. Pediatrics 2000; 105:21-6

10. Incidence and Aetiology of Community-Acquired
Neonatal Bacteremia in Mirzapur, Bangladesh
Darmstadt GL et al., J Infect Dis; 2009; 200:906-15
259 Neonatal deaths
 62% never assessed by health-care worker.
 52% occurred within 1st days of life.

11. Proportion of Births Not Attended to by Skilled Health
Personnel, 2011
Accessed: www.unicef_mgd_2013_brochure
Low birth rate in health facility, compounded by limited resources for
investigating for sepsis in low-income settings, likely to under-estimate
incidence of GBS EOD.

12. Pathogenesis of Early Onset GBS Disease
Maternal risks factors for EOD:
1. GBS bacteriuria during
pregnancy.
2. Intrapartum maternal fever
3. Prolonged rupture of
membranes (>18 Hours).
4. Premterm labor and birth.
5. Previous sibling with invasive
GBS disease.
Images adapted from: http://www.medicinenet.com/stages_of_pregnancy_pictures_slideshow/article.htm

13. Mother to Infant Transmission of GBS and Risk
for Early Onset Invasive Disease
GBS colonized mother
Non-colonized
newborn
50%
Colonized
newborn
50%
Asymptomatic
98%
Early-onset sepsis,
pneumonia, meningitis
2%
Diagram source: http://www.cdc.gov/groupbstrep/clinicians/neonatal-providers.html#slidesets
Cutland C et al. Lancet 2009; 374:1909-16; Cutland C et al. Pediatrics 2012; 130:e581-90;
Madhi SA et al. Vaccine; 2013: ; 315: D52-57
N=5099; 20.9% vaginal
colonization1,2
57% newborns
colonized2
Number cases EOD: 2.0 per 1000 live births
(2% of colonized)1-3

14. Regional Meta-analysis of Incidence of Invasive GBS
Disease, 2000-2011
0
50
100
150
200
250
Europe The Americas Africa Eastern
Mediteranean
Western Pacific Southeast Asia
Incidenceper100000livebirths
Edmond KM et al. Lancet; 2012; 379: 547-56
Need for more high-quality studies to accurately estimate
global burden of GBS
CFR: 7%(4-10) 11%(6-16) 22%(12-32) 9% (6-13)

15. Prevalence of Maternal GBS Colonization at Birth and
Expected Incidence of GBS Invasive Disease within 7
days of Birth, WHO Regions.
0
0.5
1
1.5
2
2.5
0
5
10
15
20
25
30
Africa Americas Eastern
Mediteranean
Europe South East Asia Western Pacific
ExpectedIncidenceEOD
(per1000livebirths)
Prevalenceofcolonization
WHO Region
Kwatra G et al. WSPID VIII 2013 Cape Town. Nov 19-22; Edmond KM et al. Lancet; 2012; 379: 547-56.
Expected incidence EOD= %Colonization x 50% x 2%

16. Prevalence of Maternal GBS Colonization at Birth and
Observed Incidence of GBS Invasive Disease within 7
days of Birth, WHO Regions.
0
0.5
1
1.5
2
2.5
0
5
10
15
20
25
Africa Americas Eastern
Mediteranean
Europe South East Asia Western Pacific
IncidenceEOD
(per1000livebirths)
Prevalenceofcolonization
WHO Region
Kwatra G et al. WSPID VIII 2013 Cape Town. Nov 19-22; Edmond KM et al. Lancet; 2012; 379: 547-56.
* Expected incidence EOD

17. HIV-exposed infants at increased risk of
invasive GBS disease
0
0.5
1
1.5
2
2.5
3
3.5
Early Onset Dis Late Onset Dis
Incidenceper1,000lifebirths
Timing of illness
HIV-unexposed HIV-exposed
RR: 1.69; 95%CI:1.28-2.24 RR: 3.18; 95%CI:2.34-4.36
Cutland C et al. Emerg Infect Dis; 2015: 21: 638-645

18. M o th er H IV - M o th er H IV + N ew b o rn H IV - N ew b o rn H IV +
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
S erotype-Ia
AntibodyConcentration(g/ml)
p=0.077 p=0.005
M o th er H IV - M o th er H IV + N ew b o rn H IV - N ew b o rn H IV +
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
S eroty pe-Ib
AntibodyConcentration(g/ml)
p=0.033 p=0.013
M o th er H IV - M o th er H IV + N ew b o rn H IV - N ew b o rn H IV +
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
S erotype-III
AntibodyConcentration(g/ml)
p=0.261 p=0.005
M o th er H IV - M o th er H IV + N ew b o rn H IV - N ew b o rn H IV +
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
S erotype-V
AntibodyConcentration(g/ml)
p=0.040 p=0.004
Dangor Z et al. JID, 2015. In Press
Median GBS Capsular Antibody Concentrations is lower in
HIV-infected compared to HIV-uninfected Pregnant Women
and in their infants.

19. Serotype Distribution of Invasive GBS Disease
in Neonates and Early Infancy
Edmond KM et al. Lancet; 2012; 379: 547-56

20. Serotype Distribution of Invasive GBS Disease
in Neonates and Early Infancy
Edmond KM et al. Lancet; 2012; 379: 547-56

21. Serotype Distribution in South Africa Over One
Decade
1997-1999
Ia
31%
Ib
7%II
7%
III
49%
V
6%
EOD
LOD
2004-2008
2Madhi SA et al, Annals Trop Pediatr; 2003; 23; 15-23
Ia
23%
Ib
5%
II
5%III
58%
V
3% 6%
EOD
LOD
Madzivhandila M et al. PlosOne 2011; 6: e17861

22. Possible reasons for difference between expected and observed
incidence rates of early-onset invasive GBS disease
● Screening for GBS colonization 34-37 weeks GA, coupled with
intra-partum antibiotic prophylaxis.
● Implementation of risk-based strategy for intrapartum antibiotic
prophylaxis.
● Differences in serotype associated with colonization and
virulence (invasive potential) thereof between region.
● Ethnic/genetic differences in susceptibility to colonization and
invasive disease.
● Differences in maternal anti-capsular antibody levels and
transplacental transfer to their newborns.
● Biases in case detection, due to differences in health care
access.

23. Overview
● Burden of neonatal morbidity and mortality.
● Epidemiology of invasive GBS disease.
● Immunology of invasive GBS disease and
colonization.
● Current status of vaccine development.
• Conclusions.

24. 18 studies:
14 USA
3 Europe
1 East Asia

25. Association of Maternal Serotype-Specific GBS Anti-
Capsular Antibody and Disease in Newborns of Colonized
Mothers.
Median CPS-specific IgG Concentration (ug/ml)
Type Ia Type III Type V
Mothers of Invasive
GBS Cases
0.20
(IQ: 0.06-1.68)
0.060
(0.02-0.12)
0.09
(0.04-0.80)
Mothers of Healthy
newborns
1.83
(0.20-5.54)
1.64
(0.14-5.51)
0.53
(0.07-1.0)
Baker C.J. et al J Infect Dis; 2013. Oct.

26. Absolute Risk of Early-Onset GBS Disease in Neonate
born to a Colonized Mother as Function of CPS-specific
IgG Concentration.
Most likely value.
Upper 75th percentile credibility level
Baker C.J. et al J Infect Dis; 2013. Oct.

27. Median serotype specific capsular antibody
concentrations in invasive GBS cases and matched
controls, South Africa.
Cases
Controls –mother
colonized
Median(IQR) Median(IQR)
Serotype Ia [n=27] [n=43]
Mother 0.05 (0.02-0.24) 0.29 (0.06-1.60)
Infant 0.01 (0.01-0.07) 0.19 (0.05-1.54)
Serotype III [n=29] [n=31]
Mother 0.14 (0.08-0.33) 0.29 (0.13-0.58)
Infant 0.04 (0.02-0.08) 0.15 (0.06-0.44)
Dangor Z et al. Vaccine 2015, In press

28. Baker et al. J Infect Dis 2014
Serotype specific capsular antibody levels in mothers of
cases with invasive GBS disease and controls in South Africa
and USA.

29. Newborns of Mothers colonized by serotype Ia or III more
likely to develop invasive GBS disease if the mother has
antibody <2ug/ml.
Maternal serotype specific capsular antibody protects
against invasive GBS disease in their newborns
Dangor Z et al. Exp Rev Vacc; 2015

30. Immunology of Maternal GBS Colonization
33
 Maternal colonization with Group B Streptococcus (GBS) is
principal source of infection for neonate early-onset GBS
disease.
 Spontaneous clearance and acquisition of GBS reported in
pregnant women, but association of host immune mediators
and GBS colonization unclear.
 Few predominantly cross sectional studies report higher
serotype-specific capsular polysaccharide (CPS) antibody in
colonized compared to non-colonized.

31. Serum Capsular Antibody and OPA Titers in Women Acquiring GBS
Recto-vaginal Colonization and Those Remaining Non-colonized
Between 20-37+ weeks of Pregnancy.
Capsular antibody OPA Titers
ST Ia
ST V
ST III
ST III
ST Ia
Kwatra G et al Clin Micro Infect; April 2015
New acquisition:
Non-colonized:

32.  Capsular antibody threshold ≥5 ug/ml for ST-Ia (aOR:0.37) and ≥3 ug/ml
for ST-III (aOR: 0.11) associated with lower odds of acquisition of
homotypic serotype.
 Serotype specific OPA titers ≥8 associated lower odds of serotype Ia (aOR
0.29) and III (aOR: 0.33) acquisition; with even lower odds at higher OPA
titers (≥1:32: aOR 0.05 [Ia] and 0.23 [III]).
Kwatra G et al Clin Micro Infect; April 2015
Association between Capsular Antibody and Recto-vaginal GBS
Acquisition Between 20-37+ Weeks of Pregnancy.
Neither serotype-specific antibody or OPA associated with clearance
of existing colonization. Kwatra G et al. Clin Micro Infect April 2015.

33. Positive samples were identified as those producing at least 7 SFU/ 106 PBMC, and
more than double that in the negative control well.
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
Ia III V
ElispotPositive
Intermittent carriers Persistent carriers
41.9% (18/43)
19.0% (4/21)
38.9%(7/18)
7.4% (2/27)
22.9% (2/9)
0% (0/2)
p=0.09
p=0.02
Underlying Cellular Immunity Associated with Clearance of GBS
Recto-vaginal Colonization Between 20-37+ Weeks of Pregnancy.
Kwatra G_Unpublished provisional data
Presence of serotype-specific cellular immunity associated with
clearance of existing colonization.

34. Overview
● Burden of neonatal morbidity and mortality.
● Epidemiology of invasive GBS disease.
● Immunology of invasive GBS disease.
● Current status of vaccine development.
• Conclusions.

35. GBS Serotype Ia antibodies
In mothers and infants with 0.5, 2.5 & 5.0 µg doses of vaccine or placebo
38
ELISAGMC(µg/mL)
Day 31 DeliveryScreening Day 43 Day 91Day 4
Mothers Infants
0
10
20
30
40
GBS 0.5 PlaceboGBS 5.0GBS 2.5
0
4
8
12
16
20
GBS 0.5 PlaceboGBS 5.0GBS 2.5
GBS 0.5 GBS 2.5 GBS 5.0 Placebo
N 59 60 54 54
Geometric Mean Transfer ratios 0.55 0.56 0.58 0.76
(95% CI) (0.46, 0.65) (0.48, 0.67) (0.49, 0.70) (0.66, 0.89)
Madhi SA et al. 32nd ESPID, Dublin, Ireland, May 2014

36. Routine infant vaccines responses and Safety
Responses to routine infant vaccines
●Proportions with anti-diphtheria Abs ≥ 0.1 IU/mL similar in all groups
– GMCs were highest with placebo and 0.5 µg dose of GBS.
●Proportions with anti-Pneumo Abs ≥ 0.35 µg/mL similar in all groups
– No significant differences between Placebo and GBS groups (p > 0.05)
Safety and reactogenicity
●Similar proportions of women had reactions after vaccination
– These were mainly mild or moderate expected reactions to a vaccination
– Some SAEs reported - all were associated with pregnancy, not vaccination
– One maternal death (study day 177) due to thymic mass, unrelated to vaccination.
●11 infant deaths (7 stillbirths, 4 infants) all unrelated to vaccination
●Infant development was normal through to month 12

37. Effect of Maternal HIV-infection on Immunogenicity
of GBS Vaccine
● Study performed in Malawi and South Africa with approval of local
ECs.
● 269 pregnant women enrolled and vaccinated at 24–35 weeks
gestation
– 90 HIV uninfected
– 89 HIV-infected with high CD4+ counts (> 350 cells/μL)
– 90 HIV-infected with low CD4+ counts (> 50 ≤ 350 cells/μL)
● Received one dose GBS vaccine with 5.0 µg of each glycoconjugate from
serotypes Ia, Ib and III I 0.5 mL saline for intramuscular injection
● Immune responses to GBS serotypes assessed by ELISA in:
– Maternal blood drawn on Days 1 (prevaccination), 15, 31 and at delivery,
– Infant blood at birth (cord blood) or within 72 hours, and at 6 weeks of age.
40
Heyderman R et al. 32nd ESPID, Dublin, Ireland, May 2014

38. GBS Serotype Ia antibodies
In mothers and infants with one 5.0 µg dose of GBS vaccine
41
Mothers Infants
ELISAGMC(µg/mL)
HIV+ High CD4+ HIV+ low CD4+HIV uninfected
Day 1 Day 15 Day 31 Delivery
0
2
4
6
8
10
Day 1 Day 42
0
2
4
6
8
10
• Similar immunogenicity trends observed for serotypes Ib and III
Heyderman R et al. 32nd ESPID, Dublin, Ireland, May 2014

39. HIV-exposed infants at increased risk of
invasive GBS disease
0
0.5
1
1.5
2
2.5
3
3.5
Early Onset Dis Late Onset Dis
Incidenceper1,000lifebirths
Timing of illness
HIV-unexposed HIV-exposed
RR: 1.69; 95%CI:1.28-2.24 RR: 3.18; 95%CI:2.34-4.36
Cutland C et al. Emerg Infect Dis; 2015: 21: 638-645

40. M o th er H IV - M o th er H IV + N ew b o rn H IV - N ew b o rn H IV +
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
S erotype-Ia
AntibodyConcentration(g/ml)
p=0.077 p=0.005
M o th er H IV - M o th er H IV + N ew b o rn H IV - N ew b o rn H IV +
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
S eroty pe-Ib
AntibodyConcentration(g/ml)
p=0.033 p=0.013
M o th er H IV - M o th er H IV + N ew b o rn H IV - N ew b o rn H IV +
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
S erotype-III
AntibodyConcentration(g/ml)
p=0.261 p=0.005
M o th er H IV - M o th er H IV + N ew b o rn H IV - N ew b o rn H IV +
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
S erotype-V
AntibodyConcentration(g/ml)
p=0.040 p=0.004
Dangor Z et al. JID, 2015. In Press
Median GBS Capsular Antibody Concentrations is lower in
HIV-infected compared to HIV-uninfected Pregnant Women
and in their infants.

41. Transplacental antibody transfer (cord:maternal) between
HIV-infected and HIV-uninfected mother-newborn dyads.
Dangor Z et al. JID, 2015. In Press

42. Summary: GBS Vaccines
● GBS vaccine was well-tolerated and immunogenic in pregnant
women.
● Antibodies were transferred to newborns, persisting through Day
91
● Best responses in mothers and newborns were with 2.5 µg
formulation
● Presence of GBS antibodies had no clinically significant effect on
infant responses to routine diphtheria or PCV-13 vaccines
● No safety concerns for vaccination in pregnant women
● Possibly need different dosing schedule for HIV+ women.

43. Considerations for further clinical development
of GBS capsular-based vaccines.
● Next generation formulation of pentavalent GBS vaccine.
● Challenges in licensure of GBS vaccine:
i. Limited number of countries with established high incidence.
ii. Not feasible in most high-income countries (low incidence and IAP
standard of care).
iii. Sample size >60,000 pregnant women.
● ??Licensure based on:
i. Immunological correlate of protection against invasive disease.
ii. Phase IV vaccine effectiveness study for invasive disease.

44. Conclusion
● GBS leading/common cause of neonatal sepsis in high income and
some low-middle income countries (sub-Saharan Africa).
● Uncertainty on role of GBS to neonatal sepsis, especially in South
Asia.
● Role of GBS to preterm birth and stillbirths.
● Association established between maternal serotype specific
capsular antibody and protection of infant against invasive
disease.
● Experimental GBS polysaccharide-protein conjugate vaccine
undergone phase Ib/IIa studies.
● Challenges in clinical development of GBS vaccine, which likely be
of greatest benefit to low-income countries.