The invention of the contraceptive pill has revolutionized the lives of women, but more and more of them today are abandoning it. Unknown to the general public, an unprecedented means of contraception is under development: immunocontraception by injection.
With nearly half of the pregnancies in the world that are unforeseen, the issue of contraception is more than ever at the heart of concerns. Choosing contraception is sometimes done more out of spite between restrictive, invasive means and sources of concern for health. So almost a quarter of French women do not use contraception for fear of side effects, especially those caused by hormonal birth control.
In 1972, Indian researcher Gursaran Pran Talwar noted the absence of an effective contraceptive solution without inconvenience for women. Because between the difficulties of access and the reluctance to contraceptive means, including condoms, tubal ligation is still today the most common contraceptive method in India, although it is irreversible.
Professor Talwar therefore embarked on the development of a new contraceptive: a vaccine that would prevent pregnancies for several months, almost no inconvenience.
How does immunocontraception work?
An “anti-pregnancy” vaccine is “trying to immunize an animal against itself“, summarizes Julie Levy, specialist in feline infectious diseases at the University of Florida (United States) who has worked on immunocontraceptives in animals and whose remarks are reported by the site The Atlantic. These contraceptive injections are already used for many wild animal species to control their proliferation. In humans, the vaccine is still in clinical trials.
The hormone targeted by the vaccine isHCG (human chorionic gonadotropic hormone), produced from the first days after fertilization, it is also the one sought during a pregnancy test. She is essential for pregnancyShe notably allows the embryo to implant itself and plays an essential role in its development. The vaccine will therefore aim to neutralize this hormone with the production of anti-HCG antibodies. Without it, pregnancy cannot take place.
What would be the benefits of this contraceptive vaccine?
- It would be harmless to healththe neutralization of HCG in no way affecting the functioning of the organism.
- It is not not binding. In its latest version, the vaccine requires 3 initial doses, administered a few weeks apart and then annual boosters. But as immune responses vary from person to person, an alternative that would allow sustained release of the vaccine in a single injection is being investigated.
- There is no hormonal side effects which could affect mood, libido or weight.
- I’ovulation and periods are maintained: HCG has no effect on the menstrual cycle.
- He is fully reversible : without reminder, the level of anti-HCG antibodies gradually decreases and those who wish can become pregnant.
What do we know about the efficacy of the contraceptive vaccine?
The results of the first clinical trials of this vaccine were published in 1994 and are generally very positive. However, it is more effective on some women that others.
After injection of the experimental vaccine, blood tests of the participants revealed that the immune response was insufficient for about 20% of them, not guaranteeing contraception. Unlike other vaccines that can be marketed at much lower thresholds, a contraceptive vaccine cannot be accepted below 99% effectiveness.
Where are we after 50 years of research?
Although there are still aspects to improve in the functioning of the vaccine, the biggest obstacle encountered by this project is its concept itself. First of all, pregnancy is not a diseasetreating it as with such a vaccine raises many ethical questions.
At the same time, there is a general distrust of vaccines and contraceptives. But despite funding losses and numerous interruptions, Dr. Talwar never gave up on his contraceptive vaccine project.
A vaccine also effective against certain cancers?
The latest version of the vaccine now combines two effects: a contraceptive action but also against certain cancers at an advanced stage. Indeed, many tests have shown that the vaccine would also be effective in neutralizing cancer cells in cancers involving abnormal production of HCG (breast cancer, ovarian cancer, etc.).
Having also discovered a novel vaccine against leprosy, Talwar was able to use his discoveries to improve the immune response of the contraceptive vaccine.
Slowed down by the Covid-19 pandemic, clinical trials have recently resumed. “I am healthy“Concludes Talwar, now 96, in his interview with The Atlantic, he just hopes his invention can overcome the final obstacles”before [il] don’t go away“.
Sources:
- A Vaccine for Birth Control? The AtlanticMay 2023
- Nearly half of all pregnancies are unintended, UNFPAMarch 2022
- Talwar GP, Singh O et al. A vaccine that prevents pregnancy in women. Proc Natl Acad Sci USA. 1994 Aug 30; 91(18):8532-6. doi: 10.1073/pnas.91.18.8532.
- Talwar GP, Gupta JC et al. A unique vaccine for birth control and treatment of advanced stage cancers secreting ectopically human chorionic gonadotropin. Explor Immunol. 2021; 1:398-405. doi.org/10.37349/ei.2021.00026.