An interim analysis of data from the phase III trial of Russia’s covid-19 vaccine (Sputnik V) suggests that a two-dose regimen is 91.6% effective against symptomatic disease; a protection that in people over 60 is very similar and rises to 91.8%.
Preliminary results, published in “The Lancet,” are based on analysis of data from nearly 20,000 participants, of which three quarters received the vaccine and a quarter a placebo.
The trial included 2,144 participants older than 60 years and the efficacy of the vaccine was 91.8% in this group: the vaccine was well tolerated and the safety data of 1,369 of these older adults revealed that the most common adverse effects were flu symptoms and local reaction.
These coincide with the majority of the adverse effects reported in the other groups, which were also generally mild; the severe ones (those that required hospital admission) were rare in both the placebo (0.4%) and the vaccine (0.2%) groups.
None, the authors say, were considered associated with vaccination; Four deaths were reported in the trial, none of which were considered vaccine-related.
In a comment associated with this research, Ian Jones, from the University of Reading, and Polly Roy, from the London School of Hygiene & Tropical Medicine (who did not participate in the study), state: the development of the Sputnik V vaccine has been criticized for “improper haste, shortcuts or lack of transparency ”, but the result presented here“ is clear and the scientific principle of vaccination is demonstrated ”.
“This means that another vaccine can now join the fight to reduce the incidence of covid-19.“, He assures.
Gam-COVID-Vac or Sputnik V is a two-part vaccine that includes two adenovirus vectors – rAd26-S and rAd5-S – that have been modified to express the S protein of SARS-CoV-2.
Adenoviruses are also weakened so that they cannot replicate in human cells and cannot cause disease.
This technique has been used before and its safety has been confirmed in several clinical studies, recalls the journal in a note.
In this trial, participants received a dose of rAd26-S, followed by a booster dose of rAd5-S 21 days later.
According to those responsible, the use of a different adenovirus vector for the booster vaccination can help create a more powerful immune response, since it minimizes the risk that the immune system develops resistance to the initial vector.
“Our interim analysis of the phase III randomized controlled trial has shown high efficacy, immunogenicity, and a good tolerability profile in participants aged 18 years and older,” says Inna V Dolzhikova, from the Gamaleya National Center for Research in Epidemiology and Microbiology ( Russia).
At 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%) and 62 cases (1.3%) in the placebo group, which equates to 91.6% efficacy, summarizes the study.
The vaccine induced a robust humoral response (antibody response) and a cellular immune response (T-cell response) with data from 342 and 44 participants, respectively.
This efficacy analysis only includes symptomatic cases, so further research is needed to understand the efficacy of the vaccine in asymptomatic patients.
Additionally, the mean follow-up was 48 days from the first dose, so the study cannot assess the full duration of protection.
As part of their secondary analyzes, the authors explored efficacy against moderate or severe COVID-19. At 21 days after the first dose, there were no cases of moderate or severe COVID-19 in the vaccine group and 20 cases in the placebo group, which is equivalent to 100% efficacy against moderate COVID-19 or serious.
Although the study was not designed to evaluate the efficacy of a single dose regimen, the results point to the early onset of a partially protective effect between 16 and 18 days after single dose immunization; the team recently received approval to investigate the efficacy of a single dose.
The authors also point to the need for more research to study the vaccine in adolescents and children and in pregnant women. The trial is ongoing and aims to include a total of 40,000 participants.
The Russian vaccine has been licensed in addition to Russia in 14 other countries, including Hungary, Algeria, Serbia, Argentina, Bolivia, Venezuela, Paraguay, Turkmenistan, Belarus, Kazakhstan, United Arab Emirates and Iran. And the Czech Republic, Mexico and Sri Lanka have been interested in her.
Keep reading: They find signs of a Mexican variant of the coronavirus, this is what is known