Scientific breakthroughs 2019: small vaccine, big effects

The year 2019 was rich in discoveries for the capital’s scientific community. Each in his field, researchers from the region have written new chapters in scientific history. The Sun presents to you, at the rate of one per day, the most significant breakthroughs of the year.
V Oila over 10 years that the vaccine against the human papilloma virus (HPV) is offered to girls in many countries, including Quebec since 2008. Already the first studies of its effects hinted encouraging results. But the most recent allows us to hope for a real homerun!

HPV is a “family” of around 170 viruses, which together are among the most common sexually transmitted diseases. In most cases, the infection causes no symptoms and clears up on its own, but sometimes it persists and causes genital warts. And as the virus will “play” in the DNA of cells to “reproduce”, it also sometimes leaves traces in the genetic material that lead to cancer. HPV is the cause of almost all cancers of the cervix and a majority of anogenital and throat cancers. This is why many countries are carrying out massive vaccination campaigns for young girls (and more recently boys) from primary school.

Now does it work? In 2015, an international team, including researchers from the Center de recherche du CHU de Québec (CRCHUQ), put together all the available data on the subject, an exercise called meta-analysis. And they had seen a decline in infections, which was encouraging, but was based on still very partial data. So they made an important update this year, under the direction of Mélanie Drolet (first author) and Marc Brisson (“senior” author), both of CRCHUQ. And the results, published in the prestigious medical journal The Lancet, provide the most comprehensive picture to date of the effects of the HPV vaccine at the population level.

“We just had 4-5 years of data in the first meta-analysis, and here we go to 8-9 in some cases,” says Brisson. And this is particularly important because it gives time to see not only that the decline in infections is continuing, and even getting worse, but this time it allows us to measure an effect on precancerous lesions. ”

And yes, it works – and not just a little. By comparing the figures before and after the vaccination campaigns, the authors were able to show that HPV-16 and HPV-18 infections (the most dangerous strains from the point of view of cervical cancer) fell back less than 83% among young girls aged 13-19, and 66% among 20-24 year olds. Condylomas are between 54 and 67% less numerous, depending on the age group.

And above all, precancerous lesions of the cervix are 51% less numerous in 13-19 year olds and 31% in women 20-24 year old.

Given the well-known link between this cancer and HPV, this drop is not particularly surprising – it was even expected – admits Drolet, but it was still important to check if the results were there. “The clinical trials [during the development of the vaccine, editor’s note] were promising, but we still had to go and see if it materialized in the population,” she said.

“And another thing that was not measurable in clinical trials, she continues, was group immunity [note: when a good part of the population is vaccinated against a virus, it has more difficulty circulating and unvaccinated people are therefore indirectly protected]. This is an important aspect that we managed to demonstrate in this new meta-analysis because we observed a decline in HPV in boys even if they were not vaccinated at the time when the data were taken. This effect had been predicted by mathematical models, but here we can quantify it for real. ”

The Lancet article mentions that genital warts fell 48% in boys aged 15-19 and 32% in young men aged 20-24. “Our results show convincing evidence that HPV vaccination programs have substantial impacts,” concludes the text. To the point where we can now look at “eliminating cervical cancer as a public health problem,” says Brisson. It will never drop to zero [and the HPV will not go away, so we will have to continue the vaccination, note], but this cancer could become sufficiently rare that it is no longer considered a public health problem. ”

Note that the article by M. Brisson and Mme Drolet is among the 100 researches that had the most “talk” in 2019, according to a prize list from the firm Altmetric, which specializes in measuring the impact that have scientific studies on the web. The meta-analysis ranked 92nd out of a total of 1.3 million scientific works.

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