Health In Focus
  • Three promising Zika vaccines offer hope for protection against the dreaded illness
  • Scientists confirmed complete protection in Rhesus monkeys
  • No adverse effects of the vaccine were recognised

Beth Israel Deaconess Medical Center (BIDMC) along with scientists from University of São Paulo and Walter Reed Army Institute of Research (WRAIR) have shown that there is a definite hope for a vaccine for the dreaded virus.

Zika Virus

The Zika virus causes flu-like symptoms in adults and is transmitted by the Aedes mosquito. It has risen to International concern due to the absence of a vaccine and due to its effects on the unborn child. Fetuses in the mother's womb are affected, leading to the development of microcephaly (abnormal smallness of the head). Pregnant mothers are, therefore, advised to stay away from Zika prone areas.
First Ever Zika Vaccines Offer Protection for Primates
First Ever Zika Vaccines Offer Protection for Primates

Origin of the Zika Virus

The Zika virus gets its name from the Zika forest from where it is believed to have originated in the year 1947. A number of cases of Zika were identified in Africa, Pacific Islands and South East Asia. The first ever big outbreak of Zika was reported in the Islands of Micronesia in 2007.

Another big outbreak in Brazil in 2015 found an association between Zika and Guillain-Barré syndrome (muscle weakness) and microcephaly, raising concerns about other neurological conditions due to this virus.

The World Health Organization (WHO) has declared a Public health Emergency for the Virus with travel warnings issued for people traveling to Zika prone areas.

The rise in the number of cases have prompted scientists to work on probable vaccines which could offer protection against this disease.

First for U.S

Zika has spread to the United States, where 14 people have been identified with this disease in the Broward and Miami-Dade counties. This is the first time the U.S has witnessed a spread of infection due to mosquito bite, in the recent history.

Another first is that travel advisory has been issued for people traveling to Miami and Broward, a first time ever for places withing the U.S.

Zika Vaccine

Three vaccines were studied:
  • A purified inactivated virus (PIV) which was developed at WRAIR by army researchers.
  • A vaccine that is based on adenovirus vector based and developed by BIDMC.
  • Plasmid DNA Vaccine.

Testing the Vaccines

Purified Inactivated Virus (PIV)

Scientists injected 8 Rhesus monkeys with PIV and another eight Rhesus monkeys with a false vaccine. After 4 weeks the monkeys were given a booster dose. The monkeys were then infected with infectious strain of the virus from Puerto Rico and Brazil. It was found that Rhesus monkeys that were injected with the vaccine had enough antibodies against the virus and there was no sign of the virus in the blood or any other body fluid of the monkeys.

Adenovirus Vector Based Vaccine and DNA Based Vaccine Testing

These vaccines provide a small portion of DNA coding for the outer coat of the virus and they induce the immune system to produce antibodies. 12 Rhesus monkeys were injected with either adenovirus vector based vaccine or DNA vaccine. It was found that the adenovirus vector based vaccine was more potent than the DNA vaccine. Both the vaccines provided complete protection when the monkeys were injected with infectious strain of the virus from Brazil.

Highlights of the Vaccines Tested:
  • The vaccines that were tested offered total protection for the Rhesus monkeys against the virus.
  • The vaccines were earlier tested on mice.
  • This is the first instance of Zika vaccines being effective in primates.
  • The vaccines produced no side effects.
CDC Approves Zika Vaccine Testing on Humans

The successful testing of various Zika vaccines in primates has prompted Centers for Disease Control and Prevention (CDC) to approve testing of the vaccine in humans. This would mark the first comprehensive step towards protection against the deadly virus.

References :
  1. How Zika spreads - (
Source: Medindia

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