Vaccine Shows Promise Against Mosquito-Borne Virus
Volunteers developed antibodies to chikungunya in first human trial, but shot for public use 5 years away, researcher says
Powers added that in areas like India, where chikungunya is endemic, a vaccine has been needed for years. "Now that chikungunya is in the Western Hemisphere, there is no reason not to suspect it won't be endemic in Central or South America," she said.
And as more cases show up in the southern United States, it is likely that local outbreaks will increase, Powers said. "Given the ability of mosquitos to transmit the virus, we could see outbreaks in other areas of the country," she said.
There may even come a time when the vaccine will be needed in the United States, Powers added.
"That's an absolute possibility. We don't anticipate right now that would be a huge necessity, but since this is a new virus coming into a new ecology we would have to keep the possibility open that something could change and we would have to think seriously about broader distribution of the vaccine," she said.
Powers said that chikungunya isn't the only virus people need to worry about. "Chikungunya is just one example. There are somewhere around 550 different mosquito-transmitted viruses. We have to be aware that there are more things that will be coming, and we need to be prepared for them," she said.
In this phase 1 trial, the vaccine was given in different doses to 25 healthy volunteers. To determine the effectiveness and safety of the vaccine, researchers measured at regular intervals the amount of antibodies produced against chikungunya in the participants.
The investigators found that, after the first shot, even the lowest dose produced antibodies in most patients. After a second shot, all the participants developed high amounts of antibodies. These antibodies were long-lasting and were detected six months after the last vaccination, Ledgerwood said.
The vaccine was also well-tolerated with no serious side effects, she said. Four volunteers reported mild to moderate side effects, including an increase in an enzyme in liver and heart cells that rises when these organs are damaged, and a low white blood cell count that leaves people vulnerable to infections, the researchers noted.