Two frontrunners in the race for a coronavirus vaccine have shown promising results in early trials. However, experts caution that they may still need to surpass upcoming hurdles ahead.
Two vaccine candidates, one developed by the University of Oxford and AstraZeneca and the other by a Chinese company, CanSino Biologics, both showed results proving they were safe and induced immunity in participants.
An employee is seen at the Reference Center for Special Immunobiologicals (CRIE) of the Federal University of Sao Paulo (Unifesp) where the trials of the Oxford/AstraZeneca coronavirus vaccine are conducted, in Sao Paulo, Brazil, June 24, 2020.
However, another phase remains to be carried out, where the vaccines would need to demonstrate their capability to protect against infections.
Dr. Carlos del Rio, the executive associate dean of the Emory University School of Medicine in Atlanta, compared the vaccines' progress to be at the production level in making an aircraft. The plane currently looks good and seems capable of being able to take off safely.
However, the main question still remains: Can it safely carry him to his destination?
So far, scientists are impressed with the exceptional pace of the vaccine development efforts. It would normally take a vaccine roughly a decade to go through the different development and testing stages.
But with the urgency needed as the world continues to battle the virus that has killed more than 600,000 worldwide, about two dozen coronavirus vaccine candidates are already in clinical trials all over the world.
Human Clinical Trials: The Next Big Step
For the two vaccine candidates, the next step would be to enter phase three, which is trying the vaccine on humans. It is in this stage that developers would be able to determine the true potential of their vaccine.
Dr. del Rio says that although it is uncommon for vaccine candidates to fail at this stage, it is still indeed possible. He shares how tons of HIV vaccines initially seemed to be immunogenic as they produced immune responses.
However, upon taking them to phase three trials, they suddenly fail to protect against infection. Still, he says the results have been promising so far.
Furthermore, the Oxford-AstraZeneca vaccine has already progressed to phase three clinical trials in the United Kingdom, South Africa, and Brazil. Additional trials are anticipated to start in other parts of the world, including the United States. Similarly, the CanSino vaccine is expected to commence efficacy trials in Brazil.
The Oxford-AstraZeneca trials involved 1,077 participants. However, the jab was not tested on anyone over the age of 55. On the contrary, the CanSino vaccine was tested in 508 people, including individuals over 55 and older.
However, experts believe that additional research is needed before any vaccine is to be widely administered to the public. Moreover, del Rio said that it is vital to expand and diversify the participants of the study during human trials.
Immune Responses in Vaccines
The Oxford-AstraZeneca vaccine candidate showed that it successfully triggered the production of both antibodies and T cells. Additionally, the vaccine was able to recognize and attack virus cells.
According to Paula Cannon, an associate professor of microbiology at the University of Southern California's Keck School of Medicine, scientists would normally spend several years determining whether a vaccine is good at inducing T cells, or if a combination is needed.
Unfortunately, at this time, she says that vaccine makers don't have the luxury of time as the coronavirus is rapidly spreading all over the world.
A professor of materials sciences and biomedical and chemical engineering at the University of Southern California, Pin Wang, said that it's reassuring that the side effects seen in the vaccines have so far have been manageable.
He says that although it is uncommon to have issues later on considering the current stage both vaccines have reached, he says that surprises along the way could still spring up as the coronavirus is relatively new and not everything is known about it.
