Programmatic use of serologic biomarkers to monitor the quality of

immunization services

Rockville, MD, July 24, 2015

Myron M. (Mike) Levine, M.D., D.T.P.H.

Simon & Bessie Grollman Distinguished ProfessorAssociate Dean for Global Health, Vaccinology &

Infectious Diseases,University of Maryland School of Medicine,

Baltimore, MD, USA

UN Millennium Development Goal # 4 aims to diminish mortality in children < 5 years of age by 67% by 2015

Of the 35 countries with thehighest under-five mortality,32 are in sub-Saharan Africa!!!

(State of the World’s Children, UNICEF 2014)

The Expanded Program on Immunization (EPI)

Getting vaccines to those who need them

EPI clinic, Mali

Gavi – the vaccine alliance*

Access EquityInvestment

* Originally called the Global Alliance for Vaccines and Immunization (GAVI)

Current realities for immunization services in developing countries Current realities for immunization services in developing countries

• Most vaccines require 3 doses• Most vaccines are administered

parenterally• Most vaccines are sensitive to

either excessive heat or to freezing

• Expensive new vaccines are typically supplied in single-dose vials

EPI vaccines for infants, 2014EPI vaccines for infants, 2014Target Age Vaccine• Birth BCG, OPV, HBV+

• 6, 10 & 14 wks* Pentavalent (DwPT/Hib/HBV)• 6, 10 & 14 wks* Pneumococcal conjugate• 9 (to 12$) mos**Measles• 6, 10 & 14 wks* Oral polio vaccine• 6, 10 & 14 wks* Oral rotavirus vaccine+ Where seroprevalence is high & mother to infant transmission occurs* Given at 8, 16 & 24 weeks of age in Latin America and much of Asia$ Where measles control is good and disease in infants is uncommon** A 2nd dose of vaccine in 2nd year of life is becoming routine** In some countries, yellow fever, rubella or Japanese B vaccine also given

Invasive Hib burden,Bamako, Mali

Invasive Hib burden,Bamako, Mali

Among infants age 4-11 months admitted to hospital:

• 12% of all hospital admissions were due to invasive Hib disease

• 19.3% of deaths were due to Hib

S Sow et al, Pediatr Infect Dis J 2005

Age group

Year 1 Year 2 Year 3Mean Annual

0-1 m 21.9 10.6 10.3 14.22-3 m 22.3 43.4 63.4 43.44-5 m 133.1 270.7 263.3 223.6

6-7 m 411.5 341.4 377.8 376.68-9 m 175.2 275.2 446.1 301.310-11 m

134.7 117.9 127.5 126.6

0-11 m 145.5 171.0 206.5 174.9

Incidence of invasive Hib disease per 100,000 7/2002 - 6/2005

(S Sow et al, Pediatr Infect Dis J 2005)

Testing sera for IgG anti-Hib PRP antibodies - 1

• A high titer of IgG PRP antibody (> 1.0 mcg/ml) in infants 6-8 months of age constitutes a sensitive and specific objective indicator of:– timely immunization with 2 or 3 doses of

pentavalent vaccine (which contains Hib conjugate), and;

– enduring protection against invasive Hib disease.

• Timeliness of pentavalent immunization is critical to protect young infants against pertussis and invasive Hib disease.

Impact of Hib vaccine introduction on invasive Hib disease in infants,

Bamako, Mali

12-month Transition

Period,7-05 to 6-06

23-month Intervention Period, 7-06 to 5-08

36-month BaselinePeriod,

7-02to 6-05

Invasive Hib cases/105 infants per 6-month intervals

88% reduction

S Sow et al 2009

Prevalence of serum Hib PRP antibodies in Malian infants 6-7 months of age before and 18 & 30

months after the introduction of Hib conjugate into the EPI for Malian infants

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%60.00%

70.00%

80.00%

90.00%

100.00%

Baseline 18 mos. 30 mos.

0.15 mcg/ml

1.00 mcg/ml

Serum antibody levels:

N=200 N=200N=201S Sow et al,AJTMH 2009

Serum PRN measles antibody titers in Malian infants of different ages, demonstrating the “window of vulnerability”

and the response to measles vaccine

M Tapia et al. AmJTMH 2005

Overview of antibody biomarker issues

• What antibodies should be measured?• What clinical specimens should be collected?

– Serum (gold standard)– Dried blood spots (DBS)

• no centrifugation needed in the field ; • no reverse cold chain needed

– Oral (crevicular) fluid (no sharps involved)• Are point-of-care (i.e., point-of-contact)

devices that give immediate readouts feasible?

The overarching goal --

The goal is to quantify the proportion of the target population that has objective serological evidence of being protected rather than just having been inoculated

Some explanations for “immunization failures” & other discrepancies

• Defective cold chain• Immunogenicity of the vaccine

– Even in industrialized countries, ~ 2-3% of children who receive their 1st measles vaccination do not develop PRN antibodies

• Residual maternal antibodies interfere with infant immune response (measles)

• Child responds immunologically but titer is below the protective “cut-off”

• Transcriptional errors

Linking serosurveys to immunization

coverage surveys

• Team Composition• Coordination between the

coverage survey and serosurvey teams

• Equipment needs• Detailed standard operating

procedures (SOPs)• Community buy-in:

– Participant benefits– Informed consent led by local

health workers

Pairing an Immunization Coverage Survey with a Serosurvey: making it work

Age group

Number of

woredas

Sample size in each

woreda

Tetanus Antitoxin

Measles Antibody

Hib PRP Antibody

12-23 months

3300

children Yes Yes -

6-8* months

3100

children Yes

Serosurveys linked to immunization coverage surveys in 3 districts (woredas) in Ethiopia

* This age group has not historically been used to assess immunization coverage. CVD has shown the utility of documenting high titers of Hib antibodies as evidence of receipt of pentavalent vaccine.3 collaborating teams: JSI (coverage survey); Ethiopian Public Health Institute (serosurvey) CVD, U of Maryland (serosurvey and reference laboratory)

Comparison of tetanus antitoxin

in 727 sera measured by

ELISA vs in vivo neutralization

assay(Simonsen et al

1986)

Hintalo Wajerate: pentavalent vaccine doses and tetanus antitoxin in toddlers 12-23 mos. of age

Toddlers with Coverage Survey record of

pentavalent vaccine@

GMT, tetanus

antitoxin

No. (%) of toddlers with tetanus

antitoxin titers> 0.15 IU/ml

3 doses (217 toddlers) 0.95 IU/ml 209/217 (96%)

2 doses (16 toddlers) 0.85 IU/ml 14/16 (88%)1 dose (5 toddlers) 0.75 IU/ml 4/5 (80%)238 toddlers total 227/238 (95%)

@ ”Coverage Survey record” indicates documentation of vaccination by immunization card or EPI register.

Assaieta: pentavalent vaccine doses and tetanus antitoxin in toddlers 12-23 months of age

Toddlers with Coverage Survey record of

pentavalent vaccine@

GMT, tetanus

antitoxin

No. (%) of toddlers with tetanus

antitoxin titers> 0.15 IU/ml

3 doses (57 toddlers) 0.89 IU/ml 52/57 (91%)

2 doses (9 toddlers) 0.22 IU/ml 6/9 (67%)1 dose (15 toddlers) 0.04 IU/ml 6/15 (40%)

81 toddlers total 64/81 (79%)@ ”Coverage Survey record” indicates documentation of vaccination by immunization card or EPI register.

Pentavalent vaccine coverage estimates in

infants 6-8 monthsof age,

a measure of the timeliness of

immunizations

Pentavalent vaccine-3 in toddlers 12-23 mos. of age: administrative coverage, coverage survey & serosurvey

Estimate Hintalo Arbegona Assaieta

Administrative (2013) 90% 86% 65%

JSI Coverage Survey:(Vacc. Card+ EPI Register

+ Maternal Recall)

229/263(87%)

103/251 (41%)

72/215 (35%)

Serosurvey:Number (%) with tetanus

antitoxin > 0.15 IU/ml

244/263(93%)

151/251(54%)

114/215(46%)

Hintalo Wajerate: pentavalent vaccine doses and PRP & tetanus antibodies in infants age 6-8 mos.

Coverage Survey record of Penta vaccine@

No. (%) of infants with:PRP titers

> 1.0 mcg/ml

3 doses (43 infants) 38/43 (88%)

2 doses (15 infants) 8/15 (53%)

1 dose (12 infants) 3/12 (25%)

70 infants total 49/70 (70%)@ ”Coverage survey record” indicates documentation of vaccination by either immunization card or EPI register.

DBS

Dried Blood Spots (DBS) in serosurveys

Good spots Poor quality spots

Correlation between tetanus antitoxin titers in DBS eluates vs. serum from toddlers age 12-23 months

r=0.91

Correlation between measles IgG antibody titers in DBS eluates vs. serum from the same 60 adult subjects

Measuring antibody in oral (crevicular)

fluid

Correlation of tetanus antitoxin titers measured in serum and oral fluid of 212 Malian subjects by IgG-ELISA

Tapia et al. Pediatr. Infect. Dis. J. 2006

r=0.90

Correlation of measles antibody titers in serum measured by PRN and in oral fluid by IgG-ELISA

Vertical line = protection level 120 mIU; n=212

r=0.88

Serum Measles Titer (mIU/ml)

Ora

l Flu

id M

easl

es T

iter

(m

IU/m

l)

10 100 1000 10000 1000001

10

100

1000

10000

r = 0.9281P < 0.0001n = 60

Correlation of measles antibodies measured by IgG-ELISA in serum and in oral fluid (US adults)

Correlation of measles antibodies in serum and inoral fluid measured by IgG-ELISA

Vertical line = protection level 120 mIU; n=212

r=0.92

BD Veritor™ System: Serosurvey Kit

BD Veritor™ System Serosurvey Tool30 Test KitFor Use with Oral (Gum) Swab

Specimens• Unitized Tubes with Dispense Tips

Pre-filled with assay diluent

• Pur-Wrap foam swabs – 30 each individually wrapped

Swab gums

Remove cap from unitized tube

Insert swab, swirl, remove swab

Attach dispense tip

Dispense three drops to sample well

Read in 10 minutes

Swab Sample Processing :

Tetanus Antitoxin Kits used in field trials in West Africa

Ethiopia project acknowledgments

EHNRISerosurveyBerhane BeyeneShitu HaileElfinesh DawwawTeklil BizaRajiha AbubekerEshetu LemmaTassew KassaMekonen GetahunNathanael DiresTamrat TadesseMenberu TedlaAngelo AshaBirke TeshomeAmha Kebede

CVDSerosurveyMark TravassosJames CampbellMarcela PasettiNigisti MulhollandInna RuslanovaJaya GoswamiKaren BallWilliam BlackwelderYukun WuMardi ReymannMyron M Levine

JSI Immunization Coverage Survey Zenaw Adam Anteneh Girma Lisa OotSamrawit AshenafiJenny SequeiraTewodros WoldetsadikRobert SteinglassEdris AbdellaHaileslassie TsegabuMeka Metekia

CVD MaliSeydou Diarra

Point-of-contact rapid assessment tool to detect protective titers of tetanus, measles and Hib

antibodies in oral (crevicular) fluidField site CVD-Mali, Bamako, Mali

PI Milagritos Tapia, MDCo-PI Samba O. Sow, MD, MSc

Co-InvestigatorsFatoumata Diallo, MD, Fadima Cheick Haidara, M D, Moussa Doumbia, MD, Flanon Coulibaly, MD, Auwa Traore, Pharm D, Uma Uonwuchekwa

Co-Investigators

Wilbur Chen, MD, Marcela Pasetti, PhD, William Blackwelder, PhD, Mardi Reymann, M.S.

Co-Investigator Michael Fiechtner, PhD, Rick Anderson, PhD

Coordinating Investigator Myron M. Levine, MD, DTPH

Thank you on behalf of the teams