Chinese vaccine being tested in Butantan is safe for the elderly, but generates less immune response in the group, says the company | Vaccine

According to Liu Peicheng, a company representative, he told Reuters that the CoronaVac vaccine did not cause serious side effects in the combined Phase 1 and Phase 2 clinical trials that began in May with 421 participants aged 60 and over.

“Of the three groups of participants who took two injections of low, medium and high doses of CoronaVac respectively, more than 90% had a significant increase in antibody levels, but the levels were slightly lower than those seen in younger subjects , albeit in line with expectations, “Lu said.

The results are preliminary and were obtained after testing from beginner to intermediate level. The full results were not released and were not presented to Reuters, according to the agency.

Four of the eight vaccines in the world that are in the third phase of testing are from China.

Health officials around the world want to know if investigational vaccines can safely protect the elderly, whose immune systems generally react less powerfully to immunizers against the coronavirus, which has already caused nearly 900,000 deaths worldwide. .

To CoronaVac, what being tested in Brazil and Indonesia in stage 3 (final) To assess whether it is effective and safe enough to gain mass use authorization, it has already been delivered to thousands of people, including around 90% of Sinovac employees and their families, as part of China’s emergency vaccination plan. to protect people at high risk of infection.

The Chinese candidate can remain stable for up to three years in storage, according to Liu, which may offer Sinovac some advantage in distributing the product to regions where storage in a refrigerated environment is not an option.

Videos: See the latest news on vaccine research

Steps to produce a vaccine

It takes time to produce a vaccine. The fastest developed so far was the mumps vaccine, which took about four years to be licensed and distributed to the population.

Before starting the tests in volunteers, immunization goes through several phases of preclinical experimentation (in the laboratory and with guinea pigs). Only after its safety and efficacy have been evaluated do human trials begin, the so-called clinical phase, which are three:

• Phase 1: is a preliminary evaluation of the safety of the immunizer, performed with a small number of healthy adult volunteers who are closely monitored. It is at this time that the type of response that the immunizer produces in the body is understood. It is applied to dozens of participants in the experiment.
• Phase 2: In the second phase, the clinical study is expanded and has hundreds of volunteers. The vaccine is given to people with characteristics (such as age and physical health) similar to those for whom the new vaccine is intended. In this phase the safety of the vaccine, immunogenicity (or protective capacity), the dose and how it should be administered are evaluated.
• Phase 3: Large-scale trial (with thousands of people) that should provide a definitive evaluation of its efficacy and safety in larger populations. In addition, designed to predict adverse events and ensure the durability of protection. Only after this phase can a medical history be taken.