Detailed results of the Russian-developed Sputnik V vaccine have just been published. Its overall efficacy is 91.6%, with side effects slightly more pronounced than with mRNA vaccines.
Russia announced last November that its COVID-19 vaccine, Sputnik V, was 92% effective. In the meantime, the third phase of clinical trials has continued to evaluate the vaccine’s efficacy and safety. Finally, detailed preliminary results were published in The Lancet. Do they match the announcement made a few months ago?
The efficacy of the Sputnik V vaccine is 91.6%
The analysis was conducted on 21,977 participants, all of whom were over 18 years of age and had not caught Covid-19 in the 14 days before the studies began. Most were Russian, as the trials were conducted in 25 hospitals and clinics, all located in Moscow. They were randomly assigned to the vaccine or placebo group (3:1 ratio).
The vaccine group received two injections of Sputnik V vaccine 21 days apart, while the placebo group received a buffer solution using the same protocol. Covid-19 cases were confirmed by PCR testing, but only after people reported symptoms via a mobile application. Therefore, vaccine efficacy was not calculated considering asymptomatic disease cases.
There were 16 symptomatic Covid 19 cases reported in the vaccine group (14,964 people) and 62 in the placebo group (4,902 people). The overall efficacy of the Sputnik V vaccine is estimated at 91.6%. It varies little by age group, from 90% for 31-40 years to 92.7% for 51-60 years. On the other hand, efficacy decreases significantly when gender is considered: 94.2% for men and 87.5% for women.
Most cases of Covid-19 occurred between the first and second injections. The researchers state that the first dose was 73.6% protective. No moderate or severe cases of Covid-19 were reported in the vaccine group after the second injection, resulting in 100% efficacy against the most pronounced forms of the disease.
A good safety profile
The Sputnik V vaccine was generally well-tolerated, although side effects were somewhat more severe than with other vaccines. Flu-like symptoms, local injection reactions, and asthenia (general weakness/fatigue) were the most common side effects. Among the most worrisome reactions, the researchers observed 18 cases of allergy, 29 cases of skin manifestations (rashes, itching, allergy, etc.), 8 cases of cold sores, and finally 6 cases of adenopathy.
The initial results on the efficacy and safety of the Sputnik V vaccine are good and encouraging. The vaccine is available in two forms: liquid, to be stored at -18°C, and lyophilized, to be stored at 2-8°C. Here, the liquid form was studied, but the lyophilized form was also approved by the Russian Ministry of Health. A protocol based on a single injection is also being studied, which then provides 73% protection.