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Licensed Unlicensed Requires Authentication Published by De Gruyter September 14, 2023

Pre-Exposure Prophylaxis and HIV Incidence

  • Samuel Mann ORCID logo EMAIL logo

Abstract

Pre-Exposure Prophylaxis (PrEP) is a drug that, as demonstrated in clinical trials, when taken makes the user virtually immune to HIV. This has led to numerous countries making the drug available, but little is known about the population level effects of PrEP. Using panel data from 40 European countries I study the effect of countries adopting WHO recommendations to make PrEP available to citizens. I demonstrate that PrEP availability leads to around 15–20 % fewer new HIV infections. My results indicate that PrEP can be an effective tool in reducing HIV incidence.

JEL Classification: I1; I18

Corresponding author: Samuel Mann, RAND Corporation, Arlington, USA, E-mail: .

Acknowledgments

I thank Christopher Carpenter, Gilbert Gonzales, Michelle Marcus, Benjamin Harrell, Nathaniel Tran, and two anonymous reviewers for helpful comments on an earlier draft.

Appendices
Table A1:

Goodman-bacon decompositions.

Weight Average DD
Earlier treated versus later control 0.295 −0.121
Later treated versus earlier control 0.032 0.005
Treated versus never treated 0.673 −0.156
  1. Notes: See Table 2.

Table A2:

The effect of PrEP availability on HIV, driven by a single country?

(1) (2) (3) (4) (5)
Excluding Albania Excluding Austria Excluding Belgium Excluding Croatia Excluding Czech Republic
PrEP available x post −0.157** −0.159** −0.155** −0.157** −0.152**
(0.066) (0.067) (0.067) (0.066) (0.067)
(6) (7) (8) (9) (10)
Excluding Denmark Excluding Estonia Excluding Finland Excluding France Excluding Georgia
PrEP available x post −0.155** −0.156** −0.162** −0.163** −0.156**
(0.067) (0.066) (0.066) (0.068) (0.067)
(11) (12) (13) (14) (15)
Excluding Germany Excluding Iceland Excluding Ireland Excluding Israel Excluding Italy
PrEP available x post −0.158** −0.167** −0.124* −0.132** −0.160**
(0.067) (0.068) (0.065) (0.064) (0.066)
(16) (17) (18) (19) (20)
Excluding Kazakhstan Excluding Moldova Excluding Netherlands Excluding Norway Excluding Portugal
PrEP available x post −0.185*** −0.160** −0.139** −0.173** −0.180***
(0.062) (0.066) (0.065) (0.067) (0.062)
(21) (22) (23) (24) (25)
Excluding Serbia Excluding Spain Excluding Sweden Excluding Switzerland Excluding Ukraine
PrEP available x post −0.158** −0.130** −0.155** −0.146** −0.170**
(0.066) (0.064) (0.068) (0.066) (0.064)
  1. Notes: See Table 2. Standard errors in parentheses: ***p < 0.01, **p < 0.05, *p < 0.1.

Table A3:

The effect of PrEP availability on HIV incidence.

(1)
Poisson
PrEP available x post −0.199***
(0.076)
Country and year FE
Country level controls
Law controls
  1. Notes: See Table 2. Standard errors in parentheses: ***p < 0.01, **p < 0.05, *p < 0.1.

Figure A1: 
Compositional balance. Notes: Outcome variables are standardized to have a mean of zero and a standard deviation of one to aid comparability. Each plot is a separate difference in difference specification and each specification includes controls for the other covariates as well as both state and year fixed effects. Bars denote 95 % confidence intervals.
Figure A1:

Compositional balance. Notes: Outcome variables are standardized to have a mean of zero and a standard deviation of one to aid comparability. Each plot is a separate difference in difference specification and each specification includes controls for the other covariates as well as both state and year fixed effects. Bars denote 95 % confidence intervals.

Figure A2: 
Event study model without PrEP clinical trial or implementation project. Notes: Data come from the Institute of health metrics and evaluation global burden of disease database (2005–2019). This figure overlays the event-study plots constructed using two different estimators: TWFE model, estimated (in black) and a Sun and Abraham model (in blue). The omitted period is t–1 and event periods are binned at t–5 or earlier. The event study is unbalanced due to data limitations. Countries treated in 2016 are represented in all event periods, countries treated in later years are unrepresented in later periods. The model includes the same covariates as Figure 1, except from the PrEP clinical trial or implementation project variable given its economic significance in Figure A1. Bars represent 95 % confidence intervals.
Figure A2:

Event study model without PrEP clinical trial or implementation project. Notes: Data come from the Institute of health metrics and evaluation global burden of disease database (2005–2019). This figure overlays the event-study plots constructed using two different estimators: TWFE model, estimated (in black) and a Sun and Abraham model (in blue). The omitted period is t–1 and event periods are binned at t–5 or earlier. The event study is unbalanced due to data limitations. Countries treated in 2016 are represented in all event periods, countries treated in later years are unrepresented in later periods. The model includes the same covariates as Figure 1, except from the PrEP clinical trial or implementation project variable given its economic significance in Figure A1. Bars represent 95 % confidence intervals.

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Received: 2023-03-22
Accepted: 2023-08-31
Published Online: 2023-09-14

© 2023 Walter de Gruyter GmbH, Berlin/Boston

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