Mika Enviromental Blog

For a better world

Publicado em 20 junho 2018

Por Carlos Fioravanti

Anti-HIV barrier

New drug to prevent transmission of AIDS virus is adopted and evaluated in Brazil

Sexual Pre-Exposure Prophylaxis (PrEP), the most recent strategy to prevent HIV transmission, is advancing in Brazil. It is a daily pill that prevents contamination by the AIDS virus in almost all cases. Approved in 2017 for use in the country and distributed since the beginning of this year in the public health system, the medication has attracted people at risk of becoming infected by the virus that causes AIDS, according to recent studies. Despite the progress, there is still uncertainty about the risk of PrEP promoting the abandonment of other forms of prevention, such as the use of condoms, which increases the risk of HIV transmission, gonorrhea, syphilis, chlamydia, and other sexually transmitted diseases ). According to the Ministry of Health (MS), 8% of sex workers have syphilis and most do not use condoms in sexual relationships with regular clients, boyfriends or husbands.

"The effectiveness of PrEP in Brazil depends on increasing access to this drug and providing adequate care to users," said Maria Amélia Veras, a medical epidemiologist at the Faculty of Medical Sciences of Santa Casa de São Paulo. Effectiveness is the performance of a drug in real conditions of use by a large number of users. "To function satisfactorily, this or any other HIV prevention strategy assumes that the needs of the users are taken into account and that health professionals are available to talk to them. For this to happen, we need the SUS to be strengthened with more resources and personnel. "

PrEP consists of the consumption of a tablet containing two antiviral drugs - tenofovir and emtricitabine - and is indicated for those who did not become infected with the virus and have at risk sexual intercourse with people infected with HIV. Produced by the US pharmaceutical company Gilead, the tablets are imported and, in addition to the public health system, can be bought in pharmacies or online at an average monthly cost of $ 300. There is a perspective of national production: the Institute of Pharmaceutical Technology of the Oswaldo Cruz Foundation (Farmanguinhos / Fiocruz), in Rio de Janeiro, announced in March an agreement with a national pharmaceutical company to produce tenofovir and emtricitabine. The National Institute of Industrial Property (INPI) has rejected the patent application of the two formulations in Brazil, which facilitates its production in the country, but the plan to manufacture the drugs at lower prices still depends on the approval of registration in the National Agency of Sanitary Surveillance (Anvisa).

Approved in the United States in 2012, with few side effects (including nausea and flatulence), PrEP is more than 90% effective. A study of Fiocruz researchers published in the Lancet HIV in March this year indicated a high rate of adherence to this preventive approach in Brazil: 83% of the 450 participants reached the end of the 48 weeks treatment proposals provided by the cooperating research institutions with the study. Participants were men who have sex with men and transsexual women - who identify themselves as female, although at birth have been recorded as male - non-HIV infected. All maintained sexual habits and took PrEP regularly: the proportion of people who reported having had anal sex without a condom with at least three partners did not change significantly from the beginning to the end of the time they took the antivirals.

"Withdrawal from condom use increases the risk of transmission of HIV, syphilis, gonorrhea, chlamydia, and other diseases"

The problem is that even if the drug is highly effective against HIV, dropping condom use increases the risk of transmission of other STDs. In Spain and Canada, for example, high rates of STIs have been reported among PrEP users who have sex without a condom, according to virologist Pablo Barreiro, of the Hospital Universitario Carlos III, Madrid, in an article in the journal Aids Reviews of March this year.

The most vulnerable

The MS estimates that 866,092 people are living with HIV, of which 84% have been diagnosed and 63% receive treatment. The AIDS detection rate showed a small reduction - from 19.5 cases per 100,000 inhabitants in 2015 to 18.5 per 100,000 in 2016 - but is increasing mainly among men aged 15-29. Two groups are the most vulnerable to infection and have the lowest rates of adherence to treatments. The first is that of transsexual women, with an infection rate ranging from 17% to 64%, according to preliminary MS studies. The second is that of gays and other men who have sex with men, of whom 18% have already become infected with the virus that causes AIDS, according to the MS. Among women, HIV prevalence rates are in the 15-19 age bracket (from 3.6 cases per 100,000 women in 2006 to 4.1 per 100,000 in 2016) and in the 60 5.6 in 2006 to 6.4 in 2016). In other age ranges, the trend has been declining over the past 10 years, especially among women aged 25-29 (from 30.5 per 100,000 in 2006 to 15 per 100,000 in 2016).

From early January through the end of March this year, 36 public health centers in 11 states served 1,401 people interested in PrEP. On April 5, Dr. Adele Schwartz Benzaken, director of the Department of Surveillance, Prevention and Control of Sexually Transmitted Infections, at the opening lecture of an AIDS course at the University of São Paulo Medical School (FM-USP) HIV / AIDS and MS Viral Hepatitis, has announced plans to increase the number of people served and care centers.

The first group of PrEP users in the public health network were mainly gay men and other men who had sex with men (84.5%) and white or yellow (61.3%) of high schooling, with low participation of women transsexuals and transvestites (1.2%). "We have to strive to reach the populations most vulnerable to HIV, such as low-level gays, transgenders and sex workers, who are the ones who most need PrEP," said Adele. As a strategy to stop the transmission of the virus, the public health system already offers Post-Exposure Prophylaxis (PEP), which consists of the use of other antivirals within 72 hours after high-risk exposures to HIV, with high efficacy, such as PrEP. The number of times the PEP was adopted rose from 15,414 in 2009 to 87,414 in 2017, as one person may take more than once.

Published by Pesquisa / FAPESP, edition 267, May, 2018

(Until next Wednesday, June 27, 2018)