The Lancet: Study reports preliminary efficacy and safety results from interim analysis of Russian COVID-19 phase 3 vaccine trial
Interim analysis from phase 3 trial of nearly 20,000 participants suggests efficacy of two-dose regimen of the adenovirus-based vaccine is 91.6% against symptomatic COVID-19 - trial reports 16 COVID-19 cases in the vaccine group (0.1% [16/14,964) and 62 cases (1.3% [62/4,902]) in the placebo group.
No serious adverse events were deemed to be associated with vaccination, and most reported adverse events were mild, including flu-like symptoms, pain at injection site and weakness or low energy.
Sub-analysis of 2,000 adults older than 60 years suggests the vaccine is similarly effective and well tolerated in this group.
Trial is ongoing and aiming to include a total of 40,000 participants - monitoring of safety and efficacy continues.
An interim analysis of data from the phase 3 trial of the COVID-19 vaccine from Russia (Gam-COVID-Vac) suggests that a two-dose regimen of the adenovirus-based vaccine offers 91.6% efficacy against symptomatic COVID-19. The preliminary findings, published in The Lancet, are based on analysis of data from nearly 20,000 participants, three-quarters of whom received the vaccine and one quarter received a placebo.
Serious adverse events (those requiring hospital admission) were rare in both the placebo (0.4% [23/5,435]) and vaccine (0.2% [45/16,427]) groups and none were considered associated with vaccination. Four deaths were reported in the trial, none of which were considered related to the vaccine. Most reported adverse events were mild, including flu-like symptoms, pain at injection site and weakness or low energy.
The Gam-COVID-Vac is a two-part vaccine that includes two adenovirus vectors - recombinant human adenovirus type 26 (rAd26-S) and recombinant human adenovirus type 5 (rAd5-S) - which have been modified to express the SARS-CoV-2 spike protein. The adenoviruses are also weakened so that they cannot replicate in human cells and cannot cause disease. Adenoviral vector vaccines have been previously used, and their safety has been confirmed in several clinical studies.
In this trial, participants were given one dose of rAd26-S, followed by a booster dose of rAd5-S 21 days later. The authors explain that using a different adenovirus vector for the booster vaccination may help create a more powerful immune response (compared with using the same vector twice), as it minimises the risk of the immune system developing resistance to the initial vector.
"Our interim analysis of the randomised, controlled, phase 3 trial of Gam-COVID-Vac in Russia has shown high efficacy, immunogenicity, and a good tolerability profile in participants aged 18 years or older," says Dr Inna V Dolzhikova, co-lead author, Gamaleya National Research Centre for Epidemiology and Microbiology, Russia. [1]
Worldwide, 64 candidate COVID-19 vaccines are currently in clinical assessment (including 13 vaccine candidates at phase 3) and 173 vaccines are in preclinical analyses. Phase 3 candidate vaccines include a variety of vaccine platforms, such as vector vaccines, mRNA vaccines, inactivated vaccines, and adjuvanted recombinant protein nanoparticles.
"Stopping the COVID-19 pandemic requires the introduction of different vaccines based on different mechanisms of action to cover diverse global health demands. Our vaccine, along with other SARS-CoV-2 vaccines, helps to diversify the world SARS-CoV-2 vaccine pipeline," says Dr Denis Logunov, co-lead author, Gamaleya National Research Centre for Epidemiology and Microbiology, Russia. [1]
Between Sept 7 and Nov 24, 2020, a total of 21,977 adults were randomly assigned to receive the vaccine (16,501) or placebo (5,476). The trial was conducted across 25 hospitals and polyclinics in Moscow, Russia. 14,964 participants in the vaccine group and 4,902 in the placebo group received two doses of the vaccine or placebo and were included in the primary interim efficacy analysis reported today. PCR tests were done at screening and at dose 2 (21 days). A further PCR test was done if participants reported symptoms of respiratory infection. Efficacy of the vaccine was calculated on the basis of the proportion of participants with PCR-confirmed COVID-19.
From 21 days after receiving the first dose (the day of dose 2), 16 cases of symptomatic COVID-19 were confirmed in the vaccine group (0.1% [16/14,964) and 62 cases (1.3% [62/4,902]) in the placebo group - equivalent to an efficacy of 91.6%.
The vaccine induced a robust humoral response (also called antibody response) and cellular immune response (also called T-cell response) with data from 342 and 44 participants, respectively. Six of the 342 participants did not mount an immune response following vaccination, possibly due to older age or individual characteristics.
The authors note that because COVID-19 cases were detected only when participants self-reported symptoms (followed by a PCR test), the efficacy analysis only includes symptomatic cases of COVID-19, and further research is needed to understand the efficacy of the vaccine on asymptomatic COVID-19, and transmission. Furthermore, median follow up was 48 days from the first dose, so the study cannot assess the full duration of protection.
Adverse events were monitored via electronic medical records, electronic diaries and telemedicine consultations. Data on serious adverse events were analysed for 21,862 participants who received at least one dose of the vaccine (16,427) or the placebo (5,435). 70 serious adverse events were reported in 68 participants, including 45 (0.2% [45/16,427]) participants in the vaccine group, and 23 (0.4% [23/5,435]) participants in the placebo group. None of the serious adverse events were considered associated with vaccination.
During the trial, four deaths were recorded - three ( END
Serious adverse events (those requiring hospital admission) were rare in both the placebo (0.4% [23/5,435]) and vaccine (0.2% [45/16,427]) groups and none were considered associated with vaccination. Four deaths were reported in the trial, none of which were considered related to the vaccine. Most reported adverse events were mild, including flu-like symptoms, pain at injection site and weakness or low energy.
The Gam-COVID-Vac is a two-part vaccine that includes two adenovirus vectors - recombinant human adenovirus type 26 (rAd26-S) and recombinant human adenovirus type 5 (rAd5-S) - which have been modified to express the SARS-CoV-2 spike protein. The adenoviruses are also weakened so that they cannot replicate in human cells and cannot cause disease. Adenoviral vector vaccines have been previously used, and their safety has been confirmed in several clinical studies.
In this trial, participants were given one dose of rAd26-S, followed by a booster dose of rAd5-S 21 days later. The authors explain that using a different adenovirus vector for the booster vaccination may help create a more powerful immune response (compared with using the same vector twice), as it minimises the risk of the immune system developing resistance to the initial vector.
"Our interim analysis of the randomised, controlled, phase 3 trial of Gam-COVID-Vac in Russia has shown high efficacy, immunogenicity, and a good tolerability profile in participants aged 18 years or older," says Dr Inna V Dolzhikova, co-lead author, Gamaleya National Research Centre for Epidemiology and Microbiology, Russia. [1]
Worldwide, 64 candidate COVID-19 vaccines are currently in clinical assessment (including 13 vaccine candidates at phase 3) and 173 vaccines are in preclinical analyses. Phase 3 candidate vaccines include a variety of vaccine platforms, such as vector vaccines, mRNA vaccines, inactivated vaccines, and adjuvanted recombinant protein nanoparticles.
"Stopping the COVID-19 pandemic requires the introduction of different vaccines based on different mechanisms of action to cover diverse global health demands. Our vaccine, along with other SARS-CoV-2 vaccines, helps to diversify the world SARS-CoV-2 vaccine pipeline," says Dr Denis Logunov, co-lead author, Gamaleya National Research Centre for Epidemiology and Microbiology, Russia. [1]
Between Sept 7 and Nov 24, 2020, a total of 21,977 adults were randomly assigned to receive the vaccine (16,501) or placebo (5,476). The trial was conducted across 25 hospitals and polyclinics in Moscow, Russia. 14,964 participants in the vaccine group and 4,902 in the placebo group received two doses of the vaccine or placebo and were included in the primary interim efficacy analysis reported today. PCR tests were done at screening and at dose 2 (21 days). A further PCR test was done if participants reported symptoms of respiratory infection. Efficacy of the vaccine was calculated on the basis of the proportion of participants with PCR-confirmed COVID-19.
From 21 days after receiving the first dose (the day of dose 2), 16 cases of symptomatic COVID-19 were confirmed in the vaccine group (0.1% [16/14,964) and 62 cases (1.3% [62/4,902]) in the placebo group - equivalent to an efficacy of 91.6%.
The vaccine induced a robust humoral response (also called antibody response) and cellular immune response (also called T-cell response) with data from 342 and 44 participants, respectively. Six of the 342 participants did not mount an immune response following vaccination, possibly due to older age or individual characteristics.
The authors note that because COVID-19 cases were detected only when participants self-reported symptoms (followed by a PCR test), the efficacy analysis only includes symptomatic cases of COVID-19, and further research is needed to understand the efficacy of the vaccine on asymptomatic COVID-19, and transmission. Furthermore, median follow up was 48 days from the first dose, so the study cannot assess the full duration of protection.
Adverse events were monitored via electronic medical records, electronic diaries and telemedicine consultations. Data on serious adverse events were analysed for 21,862 participants who received at least one dose of the vaccine (16,427) or the placebo (5,435). 70 serious adverse events were reported in 68 participants, including 45 (0.2% [45/16,427]) participants in the vaccine group, and 23 (0.4% [23/5,435]) participants in the placebo group. None of the serious adverse events were considered associated with vaccination.
During the trial, four deaths were recorded - three ( END