Poucy RtvSEARC. H WOR.KING PAIPER 2977

# Abstract

HIV prevalence in Soutilern Africa is the highiest in the world and the impact of HlV/AIDS In thc rcgion are devastating at all levels of society, incLidinig the wider cconomly. Governmiiient response has lagged behilid the pace of the epidemic, but programs are now begininilg to focus on a broad range of interventionis to combat its further spread and to mitigate its impact.

> Desimiond and Greener investigate the issues around **the** targeting of an eventual HIV vaccine. There is at present no vaccine against HIV. Althoughl several candidates are in the trial stage, **it** is not likely that a vaccine effective against the sub-type of the virus prevalent in Southern Africa will be available for I0-IS ycars. When it is, **it** may be expenisive, only partially effective, and confer immun1ity for a Iilimted period only, Vaccinationi programs will need to make the best use of the vaccine that is available and effective targeting wvill be essential.

The authors identify potcitial target groups for a vaccine, and estimiate how manay individuals would be in need of vaccination. They develop a method for estimating how manay cases of HIV iifectioni are likelv to be avoided for each vaccinated individual. The cases avoided are of two kinds: primary-the individual case that miglht have occurred in people who are vaccinated, and secondary-the number of peoplc that the vaccinated individual would otherwise have caused to become infected. Both of these depend on assumptions about the efficacy and duration of vaccine protection and the extent and nature of sexual risk behavior **in** the population1 groups. The authors distinguish between the HIV cases averted per vaccination and the cases averted per 100 recruits into a vaccination program.

The cases averted per 100 recruilts is used to develop a priority ranking of the identified population groups for vaccination. The authlors discuss the issue of ease of access to those groups and how the differential costs would affect the vaccination strategy. Thev conclude that an expensive vaccine should be administered to commercial sex workers first, xwhile an inexpensive vaccinie Would be better adminlistered first to general population groups, **in** particular, schoolchildreni.

Dcsmonid and Greener conclude with a discussion of currenit Icvels of public and private expenditure on HIV prevcntioni and trcatment, and the implications for an assessmenlt of the willingness to pay for an eventual HIV vaccine.

This paper-a product of l'ublic Services, Development Research Group-is part of the rcseartll projcct "Thc Economics of an HIV/AlDS Vaccine **In** Developing CouLntries: Potential Impact, Cost-Effectiveness, and Willingiess to Pay" sponsored by the European Commissioni and the World Bank. The project was launched **in** responsc to recommenidationis of tie World Bank's AIDS Vaccine Task Force. Copies of this paper are available free from the World Bank, 1818 H Street NW, Washinigtoni, DC 20433. I'lease contact Hedy Sladovich, mail stop MC3-3 I1, telephonie 202-473-7698, fax 202-522-1154, email address hsladovic]iC.sxvorldbanik.org. Policy Research Working P'apers are also posted on the Web at littp:// econ.worldbank.org. The authors may be contactcd at desimionldc I @( nu.ac.za or rgrecner Cwbidpa.bw. February 2003. (47 pagcs) _| 'lie_ **_P'olicy_** _Research Working Papei Series disseminates the IZ*7dxngs of ivork_ **_in_** _progress to_ **_cncorage_** _the excbaolge of Ideas abotit development issues. An objective oftbe series Is to get t ee stedarkgs_ **_oit quicklh_** _evso Ifrte pesentatioff s are less tbaiv polished The p>apers carrrz tbe 11.7111S of the auithors an1d shovii(l bhe cited ac cordt;kglv The finzdings, interpretationzs a7wzd conc/wlusions expressed_ **_inl_** _this paipera.re cittirel!, tho(se of tbce aulthors. Tb(`Vdo llt 101 sl1l represeilt th)e_ **_weiv_** _ou(f th)e Il/orldl Bank, Its Execultivfe Dircctors, or thie coitittries tlheY representt._

> Prodluced bv the Rcseaircii Advisorv Staff