hivtools research group the public health impact of microbicides charlotte watts ph.d

HIVTools Research Group

The Public Health Impact of

Microbicides

Charlotte Watts Ph.D.


Common Questions About Microbicides

• “If microbicides are less effective than condoms, won’t we be putting people at GREATER risk if we promote microbicides?”

• “Can microbicides really make a difference in the HIV epidemic?”


London School of Hygiene & Tropical Medicine

Charlotte Watts, Anna Foss, Lilani Kumaranayake, Peter Vickerman, Fern Terris-Prestholt

Global Campaign for Microbicides Lori Heise

Funding from the Rockefeller Foundation, DfID, Global Campaign for Microbicides, and USAID


Confronting partial effectiveness

• Will individuals switch from condoms to microbicides because they are easier to use?

• Three forms of evidence suggest that introducing microbicides will lead to more protection rather than less

evidence on current levels of condom use

experience from family planning insights from modeling


Sex-workers in East Asia and Pacific: reported

condom use in last sex act

Source: FHI behaviour surveillance surveys (1999-2000)

0

10

2030

40

50

60

7080

90

100

localised non-localised

Can Tho(KB)

Can Tho(SB)

Da Nang(KB)

Da Nang(SB)

HaiPhong(KB)

HaiPhong(SB)

Hanoi(KB)

Hanoi(SB)

HCMC(KB)

HCMC(SB)

Country, city and type of sex work

Per

cen

tag

e

% used condom at last commercial sex % used condom with last casual/main partner

Indonesia Vietnam


Men in Sub-Saharan Africa: condom use in last sex act*

Source: Macro International behavioural surveillance surveys and demographic health surveys; Measure Evaluation 1997-2002

0102030405060708090

100

Country

Per

cent

age

% usedcondom atlastcommercialsex% usedcondom withlast casualpartner

% usedcondom withlast mainpartner


Post Intervention Condom Use

Location Population Condom Use Notes

5 US cities High risk ♀ 17% Consistent use

Nicaragua General pop 7% Consistent use

Rwanda Married women

22% Regular use

Cameroon Youth 24% Last act any partner

Zimbabwe Sex workers 26% Consistent use

USA STD clients 39% Consistent use

Ukraine IDUs 24% High consistency

Bangladesh Sex workers 23% Always use last week

Indonesia Sex workers 34% Of sex acts protected

Tanzania Truck stop ♀ 43% 100% use last 5 acts


The reality of primary partnerships

• Many women are getting infected in their primary partnerships

• Consistent condom use difficult to achieve in stable relationships (few interventions have achieved consistent use in more than 30 percent of couples).

• The contraceptive aspect of existing prevention methods is a major barrier to their use.


Will women stop using condms?

• 9 existing studies – Two designs:

– 1) condom only compared to condom plus gel or

– 2) condom only compared to hierarchy of prevention options (including FC and gel);

– all but one focus on STD clients or sex workers

• 6 found that availability of additional protection options resulted in overall increase in consistent condom use

• 3 found some evidence of migration

• 3 highlight that consistent microbicide use could be achieved by women who could not use condoms


Experience from Family Planning

• Addition of each new method increases overall number of protected acts and decreases unintended pregnancies.

• Adding a new contraceptive method to those available in an existing program increases overall use by about 12 percentage points, and decreases crude birth rate by 5.3 points.

(Ross,J & E. Frankenberg.1993 Findings from Two Decades of Family Planning Research. Population Council)


The Prevention “Trade-Off”

• A low efficacy method used consistently can achieve the same protection as a high-efficacy method used less consistently

• A 90% efficacious method (like condoms) used in 20% of sex acts, provides less protection than a:– 70% efficacy used > 30% of the time– 50% efficacy used > 40% of the time– 30% efficacy used > 60% of the time


Mathematical modeling suggests….

• Under most circumstances, probable levels of condom migration do not increase risk of HIV transmission

• of individuals• of sub-populations

• Condom migration is potentially a problem only where condom use is high (> 70%) AND achieved microbicide consistency is low (< 50 % of non-condom protected acts)

(Foss et al, Shifts in condom use following microbicide introduction: should we be concerned?. AIDS 2003, 17:1227-1237)


Condom Consistency Condom Consistency

BEFORE AFTER

30% 5% 50% 32% 70% 59% 90% 86%

Some reductions in condom consistency that can be tolerated

without increasing risk

Microbicide HIV/STI efficacy = 50%; Used in 50% of acts not protected by condoms


Condom Consistency Condom Consistency

BEFORE AFTER

30% 0% 50% 0% 70% 37% 90% 79%

Reductions in condom consistency that can be tolerated without increasing risk

Microbicide HIV/STI efficacy = 50%; Used in 100% of acts not protected by condoms


What should the message about

microbicides be?


“Harm reduction” approach

• Microbicides would be promoted as an adjunct or “back-up” to condoms, not as a replacement.

• Prevention messages would shift to a hierarchy of options:

– Use a male or female condom every time you have sex; if you absolutely can’t use a condom, use a microbicide

– Use a microbicide with your condom for added pleasure and protection


Positioning microbicides

• Microbicides could be promoted specifically for use with regular partners or spouses.

• Need to ensure that not associated with lack of intimacy / trust => not have the same association as condoms

• Microbicides could be potentially be positioned as a vaginal health and hygiene product, or associated with protecting fertility by preventing RTIs.


The message should NOT be:

• “Microbicides can replace condoms.”

• “Microbicides will solve gender inequity and power imbalances in relationships and society that put women at risk.”


“Can microbicides really make a difference in the

HIV epidemic?”


Mathematical modeling of impact on HIV transmission

• Data from 73 lower income countries (countries with GDP < $1200 and all of Sub-Saharan Africa)

• Analysis uses country specific demographic, epidemiological, and health care data where available for key sub-populations: – youth 15-19 – regular partners – sex workers and clients– IDUs and sex partners


How do the models work?

• Initial data inputs:

– underlying prevalence of STDs/HIV

– levels of contact with services

– condom coverage & consistency of use; “migration”

– efficacy of microbicide against HIV & STD

• Model calculates patterns of spread of HIV & STDs over time, with current interventions only, adding on microbicides

• Generates estimates of HIV infections averted over time with and without microbicide


People with access to

existing services

HIV &

STD transmission

Sub-population Sexual partners and children

Feasible coverage in 3 years and patterns of microbicide use

Total sub-population

Sexual partners and children born to

women using microbicides

20%Infections averted


Results: Potential public health impact

• Introduction of a 60% efficacious microbicide in 73 lower income countries would avert 2.5 million HIV infections over 3 years (in men, women & infants)

– assumes microbicide is used by 20% of those individuals likely to be reached by existing services

– microbicides used in 50% of sex acts where condoms are not

– assumes 10% migration away from condom

(Watts et al, 2002)


Economic Benefits

• Health care costs averted $2.7 billion(includes only forms of care currently available--no ARVs)

(uses country-specific estimates of access to health care)

• Productivity benefits $1.0 billion

(includes time lost for work; training of replacement staff)

Watts, et al, Rockefeller Microbicides Initiative Public Health Impact Working Group, 2002


Impact is driven by coverage

2.5

1.4

3.7

1.5

2.7

3.9

0.6

1.5

1.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

10% 20% 30%

Coverage of groups in contact with services

Cum

ulat

ive

HIV

infe

ctio

ns

aver

ted

(mil

lion

s)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Pro

duct

ivit

y ga

ins

and

savi

ngs

to

Hea

lth

Sys

tem

(bi

llio

ns U

S$2

002)

Total HIV averted Direct savings to health system Present productivity gains


Public health conclusions

• Even a relatively low efficacy microbicide, used by a relatively large number of women could have an important effect in preventing HIV and STDs.

• Introduction of microbicides would result in substantial savings in health expenditures and productivity.

• Coverage (access) and consistency of use are crucial determinants of the public health impact of microbicides.


Conclusions

• Even during trials need to look forward to future promotion and distribution strategies

• Positioning, messaging and access are key to achieving the desired impact of microbicides.

• More research needed on:– how women in different settings likely to use

microbicides– Different women’s preferences about accessing

microbicides – how individuals understand and implement

hierarchical prevention messages– ways to promote microbicide use in primary

partnerships

hivtools research group the public health impact of microbicides charlotte watts ph.d

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