Three questions about HPV vaccination
The HPV vaccine contains virus-like particles (blue) that are noninfectious and stimulate the immune system to produce antibodies (red) that can prevent HPV infections.
In 2009, more than 30,000 people in the U.S. learned they had cancer linked to the human papillomavirus, or HPV. This virus is best known for causing cervical cancer, but it's also the culprit behind many cancers of the mouth, throat, anus, and genitals. Unlike many forms of cancer, for which we lack the knowledge and tools to prevent, scientists have figured out how to dodge HPV-triggered cancers—by HPV vaccination. Vaccination against HPV thwarts the viruses' spread, wrecking its ability to jump between people. Wiping out HPV could mean shutting down a big source of cancer cases—more than 3 percent of all diagnoses nationwide.
What is HPV?
HPV is a family of more than 150 viruses whose members infect human skin and mucosa, the moist membranes lining the nostrils, mouth, and genital cavities. Scientists name each member, or type of virus, with a number, in order of the viruses' discovery. Many types are harmless, some cause warts on the hands or feet, and others make fleshy bumps sprout on the genitals. HPV infection is common: More than one-half of all women between the ages of 14 and 59 catch a genital HPV. Though some "low risk" types trigger skin growths, they don't lead to the unchecked growth typical of cancer. A handful of HPVs, however, do.
Like their less-dangerous relatives, "high-risk" types slip into people's bodies through tiny tears in the body's mucosa. Normally, the body sweeps out pesky HPV intruders, but when high-risk HPVs stick around, they can cause cancer. They set up shop in the moist membranes of the anus, genitals, and mouth, shedding new viral spawn as old cells slough off. New viruses hide in these flakes of dead cells and can move from body part to body part—like from the vagina to the anus—or from person to person.
Human cells infected with high-risk HPVs have trouble stopping mistakes made in new cells. The infected cells are like an auto assembly line with no supervisor: New cars roll off the line, but some are missing pieces. Just as production mistakes can make a car ride dangerous, mistakes in infected mucosa can drive a cell toward cancer. In cervical cancers, early signs of the disease show up as precancerous lesions—clumps of cells that can morph into cancer. Because HPV-linked cancers grow slowly, more than 20 years can pass between infection and signs of the disease.
The Pap smear, a test that collects and examines cervical cells, can catch these signs early, giving patients a chance to treat the disease before it tumbles out of control. The test has been valuable for women: From 2000 to 2009, cervical cancer rates in the U.S. dropped. Used with a DNA test to spot high-risk HPVs, traditional Pap smears may be even more powerful. Still, in 2009, nearly 12,000 women were diagnosed with cervical cancer. And rates of other HPV-linked cancers have been creeping up. Nearly 13,000 new cases of mouth and throat, or oropharynx, cancer were reported in 2009; the vast majority was in men. Anal cancer rates are also climbing, especially for black and white adults. Unlike cervical cancer, there is no approved screen for other HPV-linked cancers. But there may be a way to prevent them—without the need to screen first for early lesions—and to trim cervical cancer rates even further.
How does the HPV vaccine work?
In 2006, the FDA approved a vaccine for HPV in girls and young women. The vaccine, Gardasil, is a series of three shots spaced over six months. The injections protect against infection by four types of HPV: types 16 and 18—the two responsible for most cervical, anal, genital, and oropharynx cancers— and types 6 and 11— two that trigger most genital warts. Three years later, the FDA approved the vaccine for use in boys and young men. In 2009, the FDA also approved a second vaccine, Cervarix, aimed at types 16 and 18.
Both vaccines prevent people from getting HPV infections by helping the body stockpile a medley of cellular defenses. The vaccines give the body a sneak peek at HPV—like flashing a picture of the virus's face on America's Most Wanted. Because the vaccines mimic HPV's shell—a sturdy coat that wraps around the virus's DNA—they can show the body what to look for without exposing it to harmful viral genes. When HPV knocks on the skin's door, a vaccinated person's immune system can answer with protections ready.
When HPV infects an unvaccinated person, the immune system stays alert in case the virus drops in again. The body's defenses are strong—they'll usually snuff out new infections. But the defenses of a vaccinated person can be more than 1000 times stronger. This means the vaccines' protection could last a long time without the need for a booster shot—perhaps even a lifetime.
How effective is the HPV vaccine?
In clinical trials, both vaccines blocked infection by the cancer-causing HPV types, 16 and 18, and prevented almost 100 percent of cervical lesions. Blocking infection by type 16 and 18 may stave off other cancers too. These high-risk viruses cause nearly all anal, oropharyngeal, and genital cancers that are HPV-positive. Stopping HPV can also keep warts from popping up: In a clinical trial of young men, vaccination with Gardasil slashed the rate of genital warts by nearly 90 percent.
In 2010, fewer than one in three U.S. teenage girls had received the full three-dose series. The numbers are even more modest for teenage boys. Series completion rates were especially low for Hispanic girls, poor girls, and girls without private insurance. Southern states tended to fare poorly as well. Only 20 percent of girls in Alabama and Mississippi received three doses of the HPV vaccine, compared to 55 percent in Rhode Island and 47 percent in Massachusetts.
Researchers have shown that even two doses may help safeguard against HPV. Now, scientists are working to make a single vaccine that blocks infection by all HPV types—wart-causing and cancer-causing ones alike. Today's vaccines, however, can prevent infection by two of the most common high-risk HPVs, and may be the first step toward preventing HPV-linked cancers.
Provided by National Cancer Institute
- How cervical cancer vaccines came to be Jan 19, 2013 | not rated yet | 0
- US patent awarded for Rochester's pioneering HPV vaccine work Nov 22, 2011 | not rated yet | 0
- HPV vaccination prevents genital warts in males Feb 04, 2011 | not rated yet | 0
- New HPV vaccine under study Nov 19, 2007 | not rated yet | 0
- Cervical vaccine also protects against anal cancer risk Aug 23, 2011 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Why is zone 1 in liver more prone to ischemic injury?
May 23, 2013 Hi, Is it because around central vein, there is only deoxygenated blood from the vein where as in the periphery there is hepatic artery. Also why...
How can there be villous adenoma in colon, if there are no villi there
May 22, 2013 As title suggest. Thanks :smile:
How can there be a term called "intestinal metaplasia" of stomach
May 21, 2013 Hello everyone, Ok Stomach's normal epithelium is simple columnar, now in intestinal type of adenocarcinoma of stomach it undergoes "intestinal...
Pressure-volume curve: Elastic Recoil Pressure don't make sense
May 18, 2013 From pressure-volume curve of the lung and chest wall (attached photo), I don't understand why would the elastic recoil pressure of the lung is...
If you became brain-dead, would you want them to pull the plug?
May 17, 2013 I'd want the rest of me to stay alive. Sure it's a lousy way to live but it beats being all-the-way dead. Maybe if I make it 20 years they'll...
MRI bill question
May 15, 2013 Dear PFers, The hospital gave us a $12k bill for one MRI (head with contrast). The people I talked to at the hospital tell me that they do not...
- More from Physics Forums - Medical Sciences
More news stories
In recent years, microRNAs (miRNAs) and other non-coding RNAs are small molecules that help control the expression of specific proteins. In recent years they have emerged as disease biomarkers. miRNA profiles have been used ...
Cancer 2 hours ago | not rated yet | 0
Cancer cells spread and grow by avoiding detection and destruction by the immune system. Stimulation of the immune system can help to eliminate cancer cells; however, there are many factors that cause the immune system to ...
Cancer 2 hours ago | not rated yet | 0
Researchers from London's Kingston University have begun a two-year study which could help prolong the lives of people with colorectal tumours.
Cancer 5 hours ago | 5 / 5 (1) | 0
Transformative research from Western University has identified new hormones in the body which may suppress breast cancer and stimulate the regression of breast tumors.
Cancer 6 hours ago | 5 / 5 (1) | 0
(Medical Xpress)—Curtin University researchers have found evidence that targeting specific cells in the body can reverse the effects of cancer on the immune system.
Cancer 6 hours ago | 5 / 5 (3) | 0
Two mutations central to the development of infantile myofibromatosis (IM)—a disorder characterized by multiple tumors involving the skin, bone, and soft tissue—may provide new therapeutic targets, according to researchers ...
36 minutes ago | not rated yet | 0 |
Talking on a hands-free device while behind the wheel can lead to a sharp increase in errors that could imperil other drivers on the road, according to new research from the University of Alberta.
4 minutes ago | not rated yet | 0
(AP)—Government health officials are investigating several health problems reported with potentially contaminated medications made by a Tennessee specialty pharmacy.
30 minutes ago | not rated yet | 0
(Medical Xpress)—A new study by researchers in the US has shown that an ancient virus can be modified to help in the fight against the simian immunodeficiency virus SIV, which is the equivalent in monkeys ...
6 hours ago | 5 / 5 (3) | 0 |
Women at a particular stage in their monthly menstrual cycle may be more vulnerable to some of the psychological side-effects associated with stressful experiences, according to a study from UCL.
3 hours ago | 5 / 5 (1) | 0 |
Biological processes are generally based on events at the molecular and cellular level. To understand what happens in the course of infections, diseases or normal bodily functions, scientists would need to ...
3 hours ago | 5 / 5 (2) | 0 |