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Researchers in China have conducted a phase 1/2 trial demonstrating the safety, tolerability and immunogenicity of a candidate vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the agent responsible for the current coronavirus disease 2019. (COVID-19) pandemic.
The randomized, double-blind, placebo-controlled trial showed that the inactivated SARS-CoV-2 vaccine, BBIBP-CorV, was safe and well tolerated among healthy individuals at all doses tested in two age groups (18 to 59 years and 60 years or more).
As reported in The Lancet Infectious Diseases, a robust humoral immune response was observed in all vaccine recipients.
The trial conducted by Xiaoming Yang (Beijing Institute of Biological Products) and colleagues from other institutions in China was conducted at the Liangyuan District Center for Disease Control and Prevention of Shangqiu City in Henan Province. .
Yang and his colleagues report that only mild adverse reactions were seen and no serious adverse reactions were reported in either age group.
“This is the first report of an inactivated SARS-CoV-2 vaccine tested in human participants,” say the researchers. “There is the possibility of further investigation of this inactivated vaccine for the control and prevention of COVID-19.”
Accelerated efforts to test vaccine candidates
Since the first cases of SARS-CoV-2 were first identified in Wuhan, China, late last year, the virus has infected more than 39.8 million people and caused more than 1.1 million of deaths.
People aged 60 and over and those with underlying health problems are at an exceptionally high risk of serious illness and death after infection.
In the absence of a licensed vaccine to protect against SARS-CoV-2, the ongoing COVID-19 pandemic warrants accelerated efforts to test vaccine candidates, Yang and his colleagues say.
BBIBP-CorV test, inactivated vaccine candidate against SARS-CoV-2
The team has conducted a phase 1/2 dose escalation, randomized, double-blind, placebo-controlled trial to assess the safety and immunogenicity of the inactivated SARS-CoV-2 vaccine candidate, BBIBP-CorV, in humans.
Eligible participants were healthy individuals ages 18 to 80 who tested negative for serum-specific immunoglobulin M (IgM) and SARS-CoV-2 IgG antibodies prior to enrollment.
For the phase 1 trial, 192 participants (mean age 53.7 years) were separated into two age groups (18 to 59 years and 60 years or older) before being randomized to receive the BBIBP-CorV vaccine or a placebo in two doses. Schedule at 2 μg, 4 μg, or 8 μg on days 0 and 28 by intramuscular injection in the arm.
For phase 2, participants aged 18 to 59 years (mean age 41 7 years) were randomly assigned to receive an intramuscular injection of vaccine or placebo in a single 8 μg dose schedule on day 0 or in a schedule of two 4 μg doses on days 0 and 14, 0 and 21 or 0 and 28.
The team reports that the BBIBP-CorV vaccine, given as a two-dose immunization, was safe and well tolerated at all three doses in both age groups. A robust humoral immune response was observed among all vaccine recipients.
The Phase 1 Findings
During phase 1, at least one adverse reaction occurred within the first 7 days among 42 of 144 people who received the vaccine. The most common systemic adverse reaction was fever.
Among those 18 to 59 years old, fever developed in one person in the 2 μg group, one in the 4 μg group, and two in the 8 μg group.
Among those aged 60 and over, fever developed in one person in the 8 μg group.
All adverse reactions were of mild or moderate severity, and no serious adverse events were reported within 28 days of vaccination.
In both age groups, neutralizing antibody titers were higher on day 42 among those who received the vaccine than among those who received placebo.
The findings of phase 2
During phase 2, at least one adverse reaction occurred within the first 7 days among 76 of 336 people who received the vaccine.
At least one adverse reaction occurred in 33 of those who received 8 μg on day 0; 18 who received 4 μg on days 0 and 14; 15 who received 4 μg on days 0 and 21; and ten who received 4μg on days 0 and 28.
A placebo recipient who received 4 μg on days 0 and 21 reported grade 3 fever, but this was self-limited and the participant recovered.
All other adverse reactions were mild or moderate in severity. The most common systemic reaction was fever, which developed in a person who received 8 μg on day 0; one who received 4 μg on days 0 and 14; three who received 4 μg on days 0 and 21 and two who received 4 μg on days 0 and 28.
Neutralizing antibody titers elicited by the vaccine on day 28 were significantly higher among those who received 4 μg on day 0 and then again on day 14, 21, or 28 than among those who received only 8 μg on day 0.
The potential of this vaccine
Yang and his colleagues say that the trial has shown that the BBIBP-CorV vaccine was safe, tolerable and immunogenic among healthy adults, whether they were younger than 60 years old or older than 60 years old.
“Immunization with BBIBP-CorV results in a rapid induction of immune responses against SARS-CoV-2, and would be valuable in preventing or limiting the COVID-19 pandemic,” they write.
“More clinical studies are needed to evaluate the potential of this vaccine in clinical application,” the team concludes.
