As Florida Faces Outbreak, Zika Vaccine Tests Begin

As Florida Faces Outbreak, Zika Vaccine Tests Begin
Aedes mosquitoes like this can spread diseases such as Zika to humans. Photo courtesy Tann.

With an outbreak of Zika cases in one Miami neighborhood, women are looking for ways to protect themself and their unborn child from infection. Now researchers are offering hope with the announcement that human tests of the Zika vaccine are beginning, and the vaccine could be available for infected areas next year.

The announcement comes from the National Institutes of Health (NIH) in an August 3rd press release. Their National Institute of Allergy and Infectious Diseases (NIAID) will run a human clinical trial of the NIAID Zika virus investigational DNA vaccine, created by researchers at their Vaccine Research Center (VRC) earlier in 2016. The researchers hope to establish whether the new vaccine is safe for use in humans and if it is able to generate an immune response, which could help protect people from becoming infected with the Zika virus.

The vaccine uses a plasmid, which is a small piece of DNA that produces small amounts of the Zika virus proteins. When the body encounters these proteins, it should have an immune response, creating antibodies to combat the proteins. The next time the body encounters the Zika virus, it should then be able to stop the infection.

To test the vaccine, the researchers are recruiting at least 80 healthy volunteers between the ages of 18 and 35 in three different locations across the U.S. All participants will receive an initial Zika vaccination, although some will receive another vaccination eight to twelve weeks later, some will receive their second vaccination four weeks later, and some will receive a second and third vaccination, at week four and week twenty. The dosage will remain the same for all participants. For the next seven days after vaccination, the study participants will record their temperature and any symptoms, the return for a follow-up visit within forty-four weeks of their vaccination.

By testing the Zika vaccine in this way, the researchers hope to determine if the vaccine is free of serious side effects. If so, it should be safe to try the vaccine in more people in the next phase of the trial. The researchers will also be taking a blood sample from the participants to see if the vaccine is causing an immune response. If the body’s immune system reacts to the vaccine, it should give the participants protection from infection if they were to encounter the Zika virus later on. By testing the different vaccination schedules, the researchers hope to determine which schedule is most effective for protecting people against the Zika virus.

The NIH researchers hope to have analyzed the results of the trial by January of next year. If all is well, they will then launch a Phase 2 trial in early 2017, this time targeting people in countries most affected by the Zika virus. Since these people are most at risk of catching the virus, living in an area where it is endemic, the researchers will see if the vaccine really does help protect them from infection.

The study provides hope to women of reproductive age as they face possible Zika infection. Governments of some countries where Zika exists have urged young women to try and avoid pregnancy for a couple of years until the Zika outbreak has died down. For those that do become pregnant, their baby is at risk of microcephaly and other serious birth defects. Babies born with microcephaly have smaller than normal heads, so their brains were not able to develop normally. This can lead to developmental issues, such as problems speaking, sitting, or walking later on. These children may have an intellectual disability, suffer from seizures, have hearing and vision problems, and even have problems swallowing. Because of the risk of microcephaly, a Zika infection is a serious threat to a pregnant woman and her unborn child.

The Zika virus usually spreads to humans by bites from Aedes mosquitoes, although there have been cases of the virus spreading from person to person, either through sexual contact or blood transfusions. Most people who are infected with the Zika virus will have no symptoms or only mild symptoms that last about a week, such as fever, headache, red eyes, joint pain, and rash. However, pregnant women should be cautious and try to avoid infection because the virus can affect their unborn child.

Various governments have urged women of reproductive age not to travel to areas where Zika occurs, and have urged women who live in or travel to these areas to avoid pregnancy. People can reduce their risk of contracting Zika fever by avoiding mosquito bites: using mosquito repellent, wearing long-sleeved clothing, using mosquito nets while sleeping, and dumping out containers of standing water where mosquitoes like to breed. Although these methods of avoiding Zika are not foolproof, hopefully next year a Zika vaccine will offer people in these areas protection from the disease. A vaccine may take time to develop and test, but with the new clinical trials, researchers are one step closer to vaccinating women who may become pregnant before they are infected with Zika.

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