Johnson & Johnson's Covid-19 vaccine enters third and final testing phase

Johnson & Johnson announced on Wednesday (23) that it will begin phase 3 testing of its candidate for the vaccine against Covid-19, the disease caused by the new coronavirus (Sars-CoV-2). This testing stage, which is the last one, should include up to 60,000 volunteers in 8 countries, including Brazil, and will accept participants over 60 years old and with pre-existing diseases. The minimum age to participate is 18 years.

Anvisa (National Health Surveillance Agency). Last month, it had already authorized the country's immunization tests. The agency's authorization provided for the participation of 7 thousand volunteers in 7 states (Bahia, Minas Gerais, Paraná, Rio de Janeiro, Rio Grande do Norte, Rio Grande do Sul and São Paulo). Then, a recruitment of 800 people in the Federal District was also announced. It is not clear whether they are included in the initial total. Johnson's vaccine, whose official name is Ad26.COV2.S, was developed by Janssen Pharmaceuticals, which belongs to the group, and will be applied in a single dose to half of the volunteers. The other half will receive a placebo (inactive substance) and serve as a control group.

The determination of who will receive the vaccine or the placebo will be made at random (randomized), and neither the volunteers nor the researchers will know which people received which substance (this type of study is called "double-blind").

If the vaccine's efficacy and safety are proven, it is expected that it will be available in early 2021 for emergency use, according to the company.

In phase 1 and 2 tests, which test the safety and effectiveness of a vaccine, scientists try to identify serious adverse effects and whether immunization was able to induce an immune response, that is, a response of the body's defense system. Johnson's vaccine demonstrated safety and induced an immune response in phases 1 and 2.

Tests for a vaccine typically have dozens (phase 1) or hundreds (phase 2) of volunteers, and are conducted separately. Phase 3, on the other hand, usually has thousands of participants. In the pandemic, because of the urgency to find an immunization for Covid-19, several companies have performed more than one step at the same time.

Before testing on humans, vaccines are tested on animals - usually on mice and monkeys.

In addition to Brazil, Johnson's vaccine is also expected to have phase 3 tests in Argentina, Chile, Colombia, Mexico, Peru, South Africa and the United States. The locations were chosen because of the high incidence of Covid-19. At the same time, there should also be a collaboration between Johnson and the United Kingdom in another separate phase 3 trial to explore a two-dose vaccine regimen.