[W]ouldn’t it be great if we could wipe sexually transmitted diseases off the face of the earth? If vaccinologists have a big “to-do” list out there, probably every single infectious disease is on it, including every STD. But some STDs have a higher priority than others, while other pathogens, unfortunately, don’t yield to our efforts quite as easily as other vaccine-preventable diseases.
Celebrate National Immunization Awareness Month by taking a look at a vaccinologist’s hypothetical “to-do” list below. While we already have a couple of STDs checked off that list, there is still more progress to be made!
Human papillomavirus: Gardasil, the most widely used HPV vaccine, introduced a new-and-improved version earlier this year. Gardasil 9 protects against seven strains of HPV that collectively cause 90 percent of cervical cancers and anal cancers, plus the two HPV strains that are jointly responsible for 90 percent of genital warts. Not only that, but vaccination against HPV will also reduce the frequency of “pre-cancers,” which are cellular abnormalities that can be treated before progressing into full-fledged cancer — meaning less time, money, and anxiety spent dealing with follow-up procedures and treatments. In fact, Australia is already seeing a huge nosedive in genital warts and pre-cancers — all thanks to their sky-high HPV vaccination rates.
Hepatitis A and B: Hepatitis, a disease of the liver, can be caused by several types of viruses, including hepatitis A virus and hepatitis B virus. Both can be transmitted sexually, but thanks to the vaccines, you can ask to be protected against them using a combination vaccine, meaning you’ll only have to get three shots over a six-month period rather than the five shots you’d receive if you were vaccinated for the two viruses separately.
Hepatitis A is mostly thought of as a type of food poisoning, but because it is transmitted by microscopic amounts of fecal matter, certain sexual activities, such as rimming, can pass the virus from one person to another. Luckily, while it can lead to a nasty illness, it is rarely fatal, and once the sufferer has recovered, he or she is immune for life. Hepatitis B, on the other hand, is not only transmitted through a wider range of sexual behaviors, including vaginal and anal sex, but it can also develop into a chronic infection that itself can lead to liver cancer.
[T]here are several other STDs that scientists would love to develop effective vaccines against — but, so far, that hasn’t happened. Luckily, even when we fail to produce an effective vaccine, all the research that got us to the point of failure will still help us in future efforts. So let’s celebrate the impressive research that we have under our belts — while keeping our fingers crossed for the scientific breakthroughs we need!
HIV: The holy grail in STD vaccines would have to be an effective immunization against HIV, the virus that causes AIDS. In HIV’s heyday, 30 years ago, scientists were optimistic that they’d be testing vaccines within a couple of years, but at that time they didn’t know how mind-bogglingly complicated the virus actually is, let alone how rapidly it mutates. It soon became clear that we couldn’t use old-fashioned vaccine-development techniques on a virus like HIV — we seriously had to up our game.
It takes a long time to do the research necessary just to bring a vaccine to the clinical-trial phase, and so far, only four HIV vaccines have emerged to be tested for efficacy. Three of them were ineffective. But one, called RV144, showed some promise. In a study of 16,000 adults, RV144’s efficacy teetered on the razor’s edge of statistical significance when it was shown that recipients were 31 percent less likely to acquire HIV infections. Are researchers onto something? If so, can this vaccine be improved to offer more protection? Only time will tell.
Herpes: Considering how common genital herpes is, a vaccine against it would be a blockbuster. Americans might spend nearly $1 billion each year to manage genital herpes infections, so a preventive vaccine would bring down health costs. People with herpes would no longer have to worry about informing potential partners of their status — they could simply encourage them to get vaccinated if they hadn’t been already. And new generations of young adults might not have to worry about it at all. Genital herpes infections pose risks during pregnancy and increase the chances of HIV transmission, so a vaccine would have indirect health benefits as well.
Very few herpes vaccine candidates have made it to clinical trials, and, so far, none of them was found to prevent herpes infections in recipients. However, one of these vaccines seemed to be modestly effective in reducing infection with HSV-1, the herpes virus most commonly associated with cold sores — though it can infect the genitals as well. Luckily, many scientists are working on herpes vaccines — including one of the scientists who helped develop the successful HPV vaccine. Researchers are optimistic.
Gonorrhea: In case you haven’t heard, gonococci — the bacteria that cause gonorrhea — are rapidly evolving resistance to antibiotics, which means that we might be facing a future of incurable gonorrhea. A preventive vaccine would be a huge boon to medicine. Unfortunately, gonococci have many superpowers against their human hosts, including the ability to suppress the immune system, making it more difficult to do its job. A gonorrhea vaccine would need to be able to train the immune system to develop a memory against the pathogen, but couldn’t include any of its immune-suppressing components.
Researchers at the University of Buffalo might have made a first step toward that goal when they developed an experimental vaccine that cures and prevents reinfection with gonorrhea … in mice. In mice that were already infected with gonorrhea, the vaccine allowed their immune systems to kill the bacteria while simultaneously developing an immunological memory to protect against future infections. It was a cool experiment, but success in human subjects is not guaranteed.
Syphilis: Syphilis doesn’t just wreak havoc on its adult sufferers — it’s dangerous during pregnancy as well, and eradication would mean preventing hundreds of thousands of miscarriages and stillbirths annually. The bacteria that causes syphilis, Treponema pallidum, is, unfortunately, very difficult to study in the lab — it can’t be grown, its genes are difficult to manipulate, and the bacterium itself is fragile. And, like the bacteria that cause gonorrhea, Treponema pallidum is also very wily, with the ability to evade our immune responses.
There is, however, one instance of an experimental vaccine showing results … in rabbits. And it took approximately 60 immunizations per rabbit over a period of 37 weeks to achieve immunity to syphilis. If the prospect of having to undergo five dozen vaccinations weren’t daunting enough, here’s one more thing to bum you out: That study was published in 1973, and was, thus far, the zenith of syphilis-vaccine research.
Chlamydia: Americans spend more than half a billion dollars every year dealing with their chlamydia infections. Worse than that is the human cost: Chlamydia can cause infertility, or be passed from mother to infant to cause infections and blindness. Luckily, we’re starting to make some headway in our quest to unravel the secrets of Chlamydia trachomatis, the bacteria that cause chlamydia.
The last human trial of a chlamydia vaccine took place half a century ago, and aimed to prevent blindness in children. The high point of those experiments was a vaccine that was 70 percent effective and protected vaccine recipients for three years. Efforts have stalled since then, but in June, Science described a newly developed chlamydia vaccine that seemed to be effective for six months … in mice.
While Gardasil is helping Australians to get genital warts under control, their koalas are currently being killed off by a terrible chlamydia outbreak — which is hastening the search for a chlamydia vaccine that’s effective in koalas. The silver lining for us humans is that such a vaccine could serve as a model for a human chlamydia vaccine. So keep your fingers crossed — both for the koalas’ sake, as well as for our own.
[Y]ou can receive the hepatitis vaccines from a regular health care provider or at many public health clinics, student health centers, pharmacy clinics, or other health centers. At Planned Parenthood Arizona, we can vaccinate you against HPV, and if vaccines are ever developed for HIV, herpes, gonorrhea, syphilis, or chlamydia, we’re sure to offer those, too. In the meantime, visit us to get the lowdown on how best to prevent transmission of those diseases by practicing safer sex, getting screened for STDs with your partners, and more.
Click here to check out other installments of our monthly STD Awareness series!