During my internship, I am working on a project aiming to identify the social network of injecting drug users (IDUs) consuming in the presence of other IDUs in order to better understand hepatitis C virus (HCV) and HIV transmission patterns between IDUs. Understanding transmission patterns can help improving harm reduction (HR) strategies. Focusing on a very specific community for this project got me interested in the way this kind of research can be put in place, and how the objectives and research questions are defined. I learned about Community based research (CR), a particular way of doing research involving equitably “community members, organizational representatives and researchers in all aspects of the research process” . CR can help defining relevant objectives and facilitate the implementation of the research project but also has its challenges.
A community can be defined as a group of people linked by common interests, habits, opinions or characteristics . People of a community usually face similar issues and have specific needs. As examples of communities we can cite the observant catholic community of France, LGBTQs (lesbian, gay, bisexual, transgender and queer), IDUs, immigrants originating from West Africa etc. Regarding health, every community has its own needs and priorities, and it is not always evident to identify them.
This is why community research is based on the principle that it has to deal with a question judged important by and for the community. Then, knowledge and action of the different actors (community-based and scientists) are combined to achieve a social transformation that mutually benefits both science and the community . Instead of considering a “vertical” composition of the research pathway with the community at the bottom and the researchers at the top, CR remodels this “top-down” vision by creating a horizontal hierarchy. Therefore, people who are directly concerned by the question are involved in every part of the project. Another principal idea of CR is to empower communities in order to enable them to improve their health on their own and provoke the necessary social change to produce long-term results .
Multiple CR studies about HIV transmission among LGBTQ population have been put in place. This allowed understanding risky practices and to discern knowledge gaps on HIV issues, and therefore contributed to adapting and optimizing actions and prevention along the way. For example, “IPERGAY” is a trial set up by the French research agency for HIV and hepatitis (ANRS) between 2011 and 2014 about pre-exposure prophylaxis (PrEP) efficiency among men who have sex with men (MSM) community. IPERGAY was put in place with the help of a consultative community committee, who had an important role in the protocol revision and also in discussing and developing the ethical aspects of the information and consent document. This committee was composed of several HIV and/or LGBTQ associations. Online discussions, forums and exchanges with people from the community were also consulted and Act Up-Paris (a MSM-community based, militant HIV/AIDS association) was involved in organizing a public meeting to disseminate information about the project. It is important that these discussions also include individuals that are not community leaders, and therefore not already invested in the cause so their opinion can be considered . Finally, this project led to a significant success of the PrEP, which contributed to decrease by 86 % the risk of HIV infection during risky sexual activity periods among MSM . Within the scope of “Vers Paris sans sida” (towards Paris without AIDS), a Paris city hall initiative, results from IPERGAY influenced the development of a new project “PREVENIR” which aims to evaluate the impact of the PrEP deployment associated with regular HIV screening and educational programs about sexual health (consultations in specialized centers etc.).
CR can also be conducted among IDUs populations, who usually struggle to be heard. The AERLI study was financed and supported by the ANRS and designed with Médecins du Monde and AIDES associations with the intention to evaluate the effect of an educative intervention by peers about injection practices among IDUs. In order to clearly define the objectives and needs of the community, activists have been consulted for their ability to communicate and formulate community issues . Already practiced by AIDES and Médecins du Monde, peer education about injection have proved its efficiency by reducing risky conducts and complications linked to injection (abscesses, infection etc.). This study allowed the government to consider legalizing community interventions such as peer injection education and spread it to the entire French territory as part of HR strategies .
However, CR also has its drawbacks, mainly because of the numerous actors involved and the complexity of the relations between community actors and researchers. Usually, these challenges arise when community actors are directly involved in field investigation, especially when they are in contact with the participants. Bias can also be noticed concerning results interpretation. First, associative actors can lack objectivity and perspective. In fact, associative workers are used to dealing with this specific population and can sometimes lack the neutrality necessary to standardize the way questions are asked, or subjectively interpret a certain declaration. Further, participants can think community-based investigators are not “neutral”, and this can bias their declarations. Moreover, a dual role (association worker and investigator) can be confusing for the professional, whereas it is sometimes ethically important that participation in the study does not affect the access to the community/association services and resources . Secondly, even if recruiting co-investigators from the community is valuable thanks to the proximity between the participant and the professional, it could also be source of bias if both parties already know each other in private life for example, which usually has to be avoided. Belonging to the same community as the co-investigator can also scare the participant of an eventual information leak. In any ways, social desirability bias can occur when the participant is facing someone that might have or show reactions or judgements to the interviewee’s declarations. Finally, the interpretation of results can also be distorted by the stakes of the project which are sometimes very important for the community. Even though bias can never be completely avoided, CR teams try to minimize them and one of the main recommendations is to invest in co-investigators training, follow-up and empowerment. 
 Minkler, M., & Wallerstein, N. (Eds.). (2011). Community-based participatory research for health: From process to outcomes. John Wiley & Sons.
 Larousse dictionary, http://www.larousse.fr/dictionnaires/francais/communaut%C3%A9/17551
 Emilie Henry, Bruno Spire, « Santé publique – La recherche communautaire : une approche innovante à développer sans modération », Transcriptases (144), ANRS, 2010.
 Jourdan, D., O’Neill, M., Dupéré, S. & Stirling, J. (2012). Quarante ans après, où en est la santé communautaire ?. Santé Publique, vol. 24,(2), 165-178. doi:10.3917/spub.122.0165.
 Demange E., Henry E., Préau M., De la recherche en collaboration à la recherche communautaire. Un guide méthodologique. Paris. ANRS/Coalition Plus. Coll. Sciences sociales et sida. 2012
 Molina, J. M., Charreau, I., Spire, B., Cotte, L., Chas, J., Capitant, C., … & Bernaud, C. (2016, July). Efficacy of on-demand PrEP with TDF-FTC in the ANRS IPERGAY open-label extension study. In JOURNAL OF THE INTERNATIONAL AIDS SOCIETY (Vol. 19). AVENUE DE FRANCE 23, GENEVA, 1202, SWITZERLAND: INT AIDS SOCIETY.
 Charles Roncier, « RDR Drogues – Etude AERLI: L’accompagnement à l’injection prouve son efficacité dans la réduction des risques de transmission VIH et VHC », 2014, vih.org