The Butantan Institute announced on Thursday (7) that it is developing a vaccine against the Zika virus, which can cause microcephaly in babies when the infection occurs during pregnancy. The vaccine is composed of the inactivated virus, a platform classified by the institute as ideal and safer for use in pregnant women.
The expectation is that animal tests will begin in the second half of 2024. “Researchers have been dedicated to the study of the vaccine since 2015, when Brazil faced an epidemic of the virus,” Butantan highlighted. Data from the Ministry of Health show that between 2015 and 2022, the country recorded almost 1,900 cases of congenital microcephaly.
“Proof of concept studies conducted in animals to assess the viability of the product have already shown that the vaccine is capable of generating neutralizing antibodies against Zika. The next step, scheduled for August 2024, is to conduct preclinical safety tests to check tolerability and possible adverse reactions,” said Butantan.
“Despite still being in the early stages, the expectation for the new vaccine candidate is positive. It uses classic production techniques, in addition to a traditional adjuvant, aluminum hydroxide (a compound responsible for enhancing the response and helping to maintain it in the long term). These are known and considered safe methods by the scientific community.”
According to the institute, the vaccine production process works as follows: cells are cultured in flasks, multiplied in a bioreactor, and inoculated with the virus; then, the material is filtered to eliminate cellular contaminants. The next step is the inactivation of the virus using a classical chemical reagent, followed by purification. Finally, the inactivated and purified virus is concentrated and formulated. The final product can be stored in common refrigeration – between 2 degrees Celsius (°C) and 8°C.
To achieve two suitable formulations, more than 60 different compositions have been tested in recent years. At this moment, researchers are working on the final version, which will be sent for preclinical studies. With the established formulation, the product has a stability of 100% for at least four months and proven activity for up to eight months.
“The final composition involves adding the adjuvant before the vaccine vials are packaged, a step that tends to further improve the product stability profile,” Butantan highlighted.
“It is worth noting that, without the virus in circulation, it is not possible to conduct efficacy clinical trials (phase 3) to assess whether the vaccinated individuals become less ill than the unvaccinated – another reason for the study being in its early stage. Today, there are two vaccines against Zika from foreign pharmaceutical companies being studied in patients, which are in the phases 1 (safety analysis) and 2 (immunogenicity analysis, i.e., the ability to induce antibodies) of clinical trials.”
Microcephaly
Microcephaly is a condition in which the baby’s head is much smaller than expected, requiring lifelong medical monitoring. Children may experience seizures, developmental delays, intellectual disability, motor and balance problems, difficulty feeding, hearing loss, and vision problems. In more severe cases, life expectancy can range from a few months to 10 years.
The primary way to prevent the disease is to eliminate breeding sites for the Aedes aegypti mosquito (the virus transmitter), that is, to avoid the accumulation of standing water in containers, plant pots, and old tires; install screens on windows and doors; wear long clothing (pants and long-sleeved shirts) or apply repellent to exposed areas of the body and prefer locations with protective screens and mosquito nets.
Covid-19
In Brazil, the Zika epidemic lasted for approximately one year, which, according to Butantan, slowed down the study. Scientists, however, continued to work on the virus production, inactivation, quality analysis, purification, and formulation stages. The work continued until 2020 when all the efforts of the virology teams needed to focus on covid-19, and the project had to be paused.
