2013年11月8日金曜日

HPV Vaccine Single dose may be enough

HPVワクチンは、一回の接種で効果が高いようだ。
米国では、13-17才の女性は、GardasilかCervarixを3回接種することが
推奨されている。

調査
・3回接種で130ドル。
・Cervarix
 1回の接種で、十分な抗体を生成。
 4年後に確認しても、十分な抗体を保持。
・コスタリカ女性の血液サンプル
 接種なし 113人
 1回接種 78人  Type16.18の抗体が接種なし人と比べて5-24倍。
 2回接種 192人  3回接種した人と比べて同様の抗体を保有。
 3回接種 120人

CDC
・子宮頸がんになる女性は、約10,300人/年。
・咽頭がんになる男性は、約6,700人/年。

米国の現状の報道。
だから、男性にもHPVワクチン接種をとなるようだ。
女性に感染させないためと思っていたが違った。

4年後まで、抗体が十分保有することは確認できた。しかし、13才で接種
しても17才までしか抗体が減らないことの確認でしかない。がんが発症
しないことにはならない。

副作用の研究は始まったばかり。

HPVワクチン 推奨中止で副反応報告増加か


HPV vaccine One dose just as effective as three, report says


---One Dose Of HPV Vaccine Could Provide Long-Lasting Protection; Builds 5 To 24 Times Higher Antibody Levels Than Women Without Vaccine---
By Anthony Rivas | Nov 4, 2013 07:07 PM EDT
http://www.medicaldaily.com/one-dose-hpv-vaccine-could-provide-long-lasting-protection-builds-5-24-times-higher-antibody-levels

Human papillomavirus (HPV) caused an estimated 529,000 new cervical cancer cases in 2008. In developing countries, it accounts for more than 85 percent of deaths, and 13 percent of all female cancers. With this in mind, a new study has found that some women can develop long-lasting antibodies to the virus with just one dose of the vaccine, rather than the recommended three doses - a finding that could offer hope for reducing these rates.

Helping Those Who Can't Afford The Three-Shot Series

Although there are more than 40 types of HPV that can infect the genital areas of both male and females, two strains (types 16 and 18) are responsible for more than 70 percent of all cervical cancers, while two other strains, (types 6 and 11) are responsible for 90 percent of all genital warts. Prevention includes using vaccines available worldwide, known as Gardasil and Cervarix, but only 33 percent of American females, ages 13 to 17, follow through with the recommended three-shot series, and many women in developing countries are unable to afford all three - each shot costs $130 in the U.S. - according to USA Today.

The study found that women who received just one dose of Cervarix built levels of antibodies stable enough to help fight against these strains, and that they still had these levels of antibodies four years later.

“Our findings suggest promise for simplified vaccine administration schedules that might be cheaper, simpler, and more likely to be implemented around the world,” Mahboobeh Safaeian, an investigator in the Division of Cancer Epidemiology and Genetics at the National Cancer Institute, said in a statement. “Vaccination with two doses, or even one dose, could simplify the logistics and reduce the cost of vaccination, which could be especially important in the developing world … where cervical cancer is one of the most common causes of cancer-related deaths.”

HPV is spread through genital contact, most often during vaginal or anal sex, and sometimes during oral sex. Most people won’t know that they are infected - therefore, they can pass it unknowingly - since their body can develop antibodies to the virus, causing about 90 percent of infections go away on their own, according to the Centers for Disease Control and Prevention (CDC). But if the virus doesn’t go away, it can lead to genital warts, and a number of cancers, including vaginal, penile, and oropharyngeal. 

One Dose Is Way Better Than None

The researchers looked at blood samples drawn from 78, 192, and 120 Costa Rican women who received one, two, and three doses of the shot, respectively. They then compared the samples with 113 women who had not received vaccination, but had developed antibodies from HPV exposure in the past. For years later, they found that every woman that got a vaccine developed antibodies to types 16 and 18 of the virus. Those who were given two doses six months apart showed antibody levels comparable to those who were given three doses. Meanwhile, women who got one or two doses showed antibody levels that were five to 24 times higher than those in women who didn’t get any vaccine.

Both Gardasil and Cervarix are intended for females, ages nine to 26, over the course of 6 months. The second dose usually comes two months after the first, and a third booster shot comes at the six-month mark. In order to reduce the spread of infection, or the development of cancer, health care providers have recently begun suggesting that boys get vaccinated as well.

About 79 million Americans are presently infected with HPV. Each year in the U.S., the virus causes about 10,300 women to develop cervical cancer, and 6,700 men to develop oropharyngeal cancer, according to the CDC.

In April, a study on Gardasil found that only two doses of the vaccine helped women develop as many antibodies as those who had received three doses, and that they maintained those levels over the course of three years. Although the results of both studies are promising, Safaeian said that there needs to be more research on the efficacy of a single dose of Gardasil, as well as longer-term studies before policies can be changed.


---A single dose of HPV vaccine may be enough---
November 4th, 2013
10:27 AM ET
http://thechart.blogs.cnn.com/2013/11/04/a-single-dose-of-hpv-vaccine-may-be-enough/?hpt=hp_bn13

Just one dose of the HPV vaccine Cervarix appears to provide enough of an immune response to protect women from two strains of human papillomavirus (HPV) and ultimately cervical cancer, according to a new study published Monday.

HPV is the most common sexually transmitted infection (STI), according to the U.S. Centers for Disease Control and Prevention (CDC). The infection, transmitted through genital contact, is the primary cause of cervical cancer, which affects about 10,300 women in the United States each year.  It causes about 275,000 deaths annually worldwide and is a leading cause of cancer deaths among women in low-income countries, according to the World Health Organization.

“Cervical cancer is a major cause of public health concern, especially in less developed countries where about 85% of cervical cancer occurs,” says study author Mahboobeh Safaeian. “The reason for that is mainly because of lack of screening infrastructure offered.”

Safaeian and her team followed a group of women in Costa Rica who were participating in the National Cancer Institute-funded phase III clinical trial testing the efficacy of Cervarix.  About 20% of these women did not complete the three-dose vaccine regimen. Safaeian compared the groups of women who had received one, two and three doses of the vaccine, as well as women who had antibodies from having been naturally infected.

The researchers found that women vaccinated with a single dose of Cervarix, as opposed to the current CDC recommendation of three, had antibodies against HPV that remained stable in their blood after four years. The findings suggest that the common recommendation for three doses may not be necessary to ensure long-lasting antibodies that prevent HPV.  Safaeian, a researcher for the National Cancer Institute's Division of Cancer Epidemiology & Genetics, Infections and Immunoepidemiology, says this could have significant implications for women across the world by simplifying the logistics and costs of vaccinations.

“This vaccine is about $130 a dose ... It’s just not feasible in a lot of undeveloped countries,” Safaeian explains.

Even in the United States, where vaccinations are easily accessible and covered under health insurance and federal programs for children, many women are not getting all three doses.  In 2012, only about half of girls between ages 13 and 17 started the HPV vaccination regimen and only about a third had received all three doses, according to the CDC.

Dr. Kevin Ault, a physician and professor at the Emory University Department of Gynecology and Obstetrics, emphasizes that it is always easier to get people into the office for a one-time vaccination. In countries outside the United States, one stop may be the only option.

“Certainly if you’re in South Asia or Africa, where you have a high burden of cancer and screening is expensive, a single dose vaccine would really be a game changer,” says Ault, who worked on the clinical trials that led to the approval of the first HPV vaccine Gardasil, which protects against four strains of HPV.

However, while this new study reveals promising results for one and two doses of Cervarix, Ault does not see this changing the standards in the United States anytime soon.  He said he believes further research will be conducted in the following years, for Cervarix and also for Gardasil, the more common of the two HPV vaccines in America. Gardasil has not yet been tested for the efficacy of less than three doses.  Until then, Ault plans to stick to the CDC recommendation of the three-dose vaccine for his patients.

Safaeian also stresses that this research is still at the beginning stages.  She notes that long-term protection is one of the outstanding questions.
“The data we have thus far only goes up to four years,” Safaeian emphasized.  “Ideally, you would want protection to last 10 to 15 years.  So, we still are not there yet - the studies have not gone that far.”

Some countries, such as Chile, have already implemented a two-dose vaccination plan, but Safaeian said that it’s still too early to tell whether it is sufficient for long-term protection.

Safaeian continues to move forward with her research, following the same participants to see whether the antibody stability extends beyond the four years.  She said that while it’s not over yet, her team has “provided some intriguing research that could help discussions of what should be the next step for evaluating number of doses.”

The new study was published Monday in Cancer Prevention Research, a journal of the American Association for Cancer Research.

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