Bharat Biotech's Zika vaccine to enter Phase 2 clinical trials soon

As Zika virus infections are spreading across India, Hyderabad-based Bharat Biotech has said its vaccine for it is set to enter Phase 2 human clinical trials soon.

Doctors have pointed out that the lack of diagnostic testing options for Zika infections may leave many cases undetected, and they may pass off as dengue or viral fever because the symptoms are largely similar. Leading private testing laboratories (labs) have told Business Standard they are now gearing up to add the Zika-virus test on the menu.

Bharat Biotech had said in 2016 it had achieved a breakthrough in developing the world’s first promising candidate, named ZIKAVAC, for the Zika virus. 

“We believe we have an early-mover advantage in developing the ZIKAVAC and we are probably the first in the world to file for a global patent for Zika vaccine candidates,” the company had then said.

It had two vaccines under development then. One of them was an inactivated vaccine that had reached preclinical testing in animals. The company has again started working on its Zika vaccine — BBV121.

“BBV121 (the Zika vaccine) is under active product development and Phase 2 human clinical trials will follow,” Bharat Biotech told Business Standard.

In 2016, Big Pharma companies like Pfizer, Johnson & Johnson, and Merck were evaluating developing a Zika vaccine.

According to global reports, several Zika vaccine candidates on a variety of platforms are under development — plasmid DNA technology, mRNA, attenuated-live virus, viral vector vaccines, etc.

The Zika virus — a mosquito-borne flavivirus — was first isolated in 1947 from the blood of a rhesus macaque in the tropical Zika Forest near Entebbe in Uganda. There have been outbreaks ever since, mostly in Africa and South America. It peaked in early 2016, with the cumulative number of documented and suspected cases exceeding 1 million. But 2017 onwards, cases have been waning.

India has never been one of the key geographies where the virus created epidemics. However, a study by scientists of the Indian Council of Medical Research (ICMR), published in the Frontiers in Microbiology in June, showed the virus had been ‘silently’ spreading across the country.

Surveillance in 2021 showed the virus’ presence in states like Kerala, Uttar Pradesh, and Maharashtra. Enhanced surveillance confirmed its presence in Jharkhand, Rajasthan, Punjab, Telangana, and Delhi in the same year. The ICMR experts noted cases in new states indicated local virus transmission.

The problem with detecting Zika virus cases lies in the lack of widespread diagnostic tools, say doctors.

K Seshi Kiran, consultant physician, Yashoda Hospitals, Hyderabad, said: “There is hardly any private lab testing of the Zika virus. Therefore, even if we suspect any cases, it is difficult to verify them.”

Several viral fever cases upon investigation turn out to be dengue-negative, he added.

Anita Mathew, infectious disease specialist, Fortis Hospital, Mulund (Mumbai), said most patients would complain of fever, redness in the eyes or conjunctivitis, rashes, bodyache, and joint pain. Since there is no specific medication for Zika, patients are given symptomatic treatment and the symptoms usually go within a week or so.

The problem occurs when a pregnant woman is infected.

“A Zika virus infection during pregnancy is a cause of microcephaly and other congenital abnormalities in the developing foetus and newborn. This also results in pregnancy complications, such as foetal loss, stillbirth, and preterm birth,” noted the World Health Organization.

Microcephaly is a birth defect where a baby’s head is small when compared to others of the same gender and age. Babies with microcephaly often have brains that might not have developed properly, said the Centers for Disease Control and Prevention in the US.

Kiran and Mathew said while the virus was mostly transmitted through mosquito bites (day-time bites similar to dengue), there were instances when transmission happened through sexual intercourse.

“The Zika virus can be detected through reverse transcription-polymerase chain reaction, blood, urine, and semen tests. If the virus is found in the semen, abstinence for at least eight weeks is advised,” said Kiran.

A leading private diagnostic lab chain that tests for chikungunya, dengue, malaria, and other such vector-borne diseases said it did not do so for Zika because only government virology labs were allowed to do so. Labs, however, are reaching out to ICMR to allow them to test to pick up Zika cases.

Another Delhi-based lab pointed out at the moment the number of cases was too low to allow for affordable pricing.

The silver lining, say infectious disease specialists like Mathew and Kiran, is that the Zika virus infection is benign compared to malaria, dengue, and chikungunya, and mostly resolved on its own with hardly any deaths.

ZIKA spread in INDIA

• May to October 2021 – clinical samples of 1475 patients across 13 states collected
• Samples screened for dengue, chikungunya, and Zika by CDC Trioplex RT-PCR
• 67 samples – Zika positive; 121 samples – Dengue positive; 10 samples Chikungunya positive
• All Zika cases were symptomatic with fever (84%), rash (78%) as major presenting symptoms
• 4 patients had respiratory distress, 1 patient had seizures, one suspected microcephaly at birth
• The Asian Lineage of Zika and all 4 serotypes of dengue were found in circulation

Source: Zika a Vector Borne Disease Detected in Newer States of India Amidst the COVID-19 Pandemic published in the Frontiers in Microbiology

ZIKA COMES BACK TO BITE
 

Vaccine efforts against virus

• Bharat Biotech’s BBV121 to go into Phase 2 human clinical trials soon
• In 2016, it had said it was probably the first globally to file a patent for the Zika vaccine
• In 2016, Big Pharma firms like Pfizer, Merck, and Johnson & Johnson had evinced an interest in the Zika vaccine
• Global reports suggest plasmid DNA, mRNA, viral vector, inactivated virus, and live-attenuated virus vaccines under development