Updated: September 5, 2020 8:08:10 am
The vaccine is the first in the world licensed for general use. (Photo: AP)
The much-criticized Russian vaccine against the novel coronavirus was found to be safe and also triggered a “strong” immune response, according to results of phase 1 and phase 2 clinical trials published in The Lancet.
The vaccine is the first in the world licensed for general use. It was approved by the Russian government on August 11, without phase 3 trials, drawing global criticism. The phase 1 and phase 2 trials were completed in less than two months, and now it appears they were conducted in just 76 people.
What is the vaccine?
The vaccine, developed by the Gamaleya Institute in Moscow, uses two adenoviruses to inject the genetic material of the new coronavirus into humans in order to trigger an immune response. Adenoviruses, which cause a variety of respiratory diseases in humans, are used as carriers to deliver various existing drugs and vaccines for other diseases as well, having lost their ability to replicate.
What were the trials whose results have been reported?
The vaccine developers conducted two separate studies, both related to phase 1 and phase 2, in two Moscow hospitals. The 76 participants included 38 anywhere.
Two variants of the vaccine were used, using different adenoviruses. In phase 1 of each study, nine people were injected with one formulation and nine the other. In phase 2 of both studies, 20 participants received injections of both formulations.
Lead author Denis Logunov from the Gamaleya Institute explained why two formulations were used. “To form a powerful immune response against SARS-CoV-2, it is important that a booster vaccine is provided. However, booster vaccines using the same adenovirus vector may not produce an effective response because the immune system can recognize and attack the vector (carrier). This would prevent the vaccine from entering people’s cells and would teach the body to recognize and attack SARS-Cov2. For our vaccine, we use two different adenovirus vectors in an attempt to prevent the immune system from becoming immune to the vector, ”Logunov said.
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What was the results?
The published findings say that “both vaccine formulations were safe and well tolerated.” Participants complained of some side effects, but these were not serious. “The most common adverse events were injection site pain (58 percent of participants), hyperthermia (or high temperature in 50 percent of participants), headache (42 percent), asthenia (or lack of energy, 28 percent) and muscle and joint pain (24%). Most of the adverse events were mild and no serious adverse events were detected, ”the study says.
Furthermore, all of the participants were found to have produced antibodies against the coronavirus, showing that the vaccine was able to trigger an immune response.
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How important are these findings?
The results show that the vaccine is at least safe to use and does not harm the person. However, the relatively small number of volunteers who participated and the short duration of follow-up (42 days) might not satisfy all experts.
In the absence of phase 3 trials, questions remain about the efficacy of the vaccine. In phase 3, a candidate vaccine is tested in several hundred volunteers in real-life situations, outside of laboratory conditions, to assess whether the immune response generated is capable of effectively fighting the disease. Participants are usually followed for several months to study the impact of the vaccine on their ability to fight the disease.
Following criticism, Russia had said that it would also hold phase 3 trials and that the August 11 clearance was only “conditional.” Phase 3 trials are scheduled to begin soon in several countries. The developers had previously planned to test the vaccine on 2,000 volunteers in phase 3, but later said they would enroll 40,000.
How are other important vaccine candidates progressing?
There are three other leading vaccine candidates, developed by Pfizer, the University of Oxford in collaboration with AstraZeneca, and Moderna. All three are currently in phase 3 trials.
At least two Chinese vaccines have also been approved without phase 3 trials, and these two also plan to begin end-stage trials soon. In addition, about 30 other candidate vaccines are currently in phase 1 and phase 2 trials.
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