Sputnik V: How Can Efficacy be Measured with 76 Volunteers?

Sputnik V :

The Russian COVID-19 vaccine candidate Sputnik V, is an adenoviral-based vaccine produced against SARS-CoV-2 corona virus. Sputnik V uses a weakened virus to deliver small parts of a pathogen and stimulate host's immune response.

It is a vector vaccine based on adenovirus DNA, where the SARS-CoV-2 corona virus gene is integrated. Adenovirus is used as a container to deliver the coronavirus gene to cells, start the synthesis of the envelope proteins of the new coronavirus introducing the immune system to a potential enemy.

The Russian vaccine Sputnik V intends to reduce the time taken for the actual development of immunity to SARS-CoV-2, the virus behind the COVID-19 pandemic.

The trail carried out, was an open two-stage non-randomized Phase 1/2 study with the participation of (38) healthy volunteers. This clinical trial is an open study of safety, tolerability, and immunogenicity of the drug "Gam-COVID-Vac ", solution for intramuscular administration, with the participation of healthy volunteers.

(Note:

A safety and tolerability assessment of the drug "Gam-COVID-Vac ", solution for intramuscular administration, using single dose of each component (Stage 1). A safety and tolerability assessment of the drug "Gam-COVID-Vac ", solution for intramuscular administration, using prime-boost immunization according to the proposed scheme (Stage 2).
Combining these two phases total 76 individuals were exposed to vaccine. )

To carry out the trial, two groups of volunteers were selected out of a pool of military personnel and civilians.
The vaccine had goal of determination of antigen-specific antibody titer in blood serum by ELISA by comparison with baseline values before the vaccine administration and at days 14, 21, 28, and 42 after vaccination (hereinafter, the countdown comes from the first time of the vaccine administration) and determination of virus-neutralizing antibody titer before and at days 14, 28, and 42 after vaccination.

Besides those, also the determination of antigen-specific cellular immunity (specific T-cell immunity) before the vaccine administration and at days 14 and 28 after vaccination.

In May 2020, a state institute, the Gamaleya National Research Centre of Epidemiology and Microbiology, announced that it had developed the vaccine, which does not have any side effects. The first vaccination leads to humoral cellular immunity and once a second vaccine is administered, a key feature of this vaccine kicks in—memory cells are formed.
On August 1, 2020, the Russian Health Minister Mikhail Murashko declared that the clinical trial had been completed.

Well, happy that we have the cure but the vaccine, developed by the Gamaleya Research Institute of Epidemiology and Microbiology, still has to complete final trials, which raises serious concerns among some scientific experts as well as the government about the speed of its approval.
Whereas only about 10 per cent of clinical trials are observed to be successful, and the speed at which Russia has moved, approving a vaccine before the final stages of trials to test safety and efficacy are over, has worried some scientists, who fear Moscow may be putting national prestige before human safety, unless they have proper trial results.
Kirill A. Dmitriev, CEO of the Russian Direct Investment Fund, said in one of his inerviews, clinical trials were expected to start soon in the United Arab Emirates and the Philippines.

The World Health Organization doubts, that it has not received enough information on the Russian COVID-19 vaccine to evaluate it. Jarbas Barbosa, the assistant director of its regional branch, the Pan American Health Organization, said that, plans to produce the potential vaccine in Brazil should not go ahead until Phase 2 and 3 trials are completed to guarantee its safety and effectiveness.

The vaccine's approval by the Health Ministry comes before the start of a larger trial involving thousands of participants that is phase 3  trial.
I personally think that health ministry is becoming reckless still approving a vaccine with incomplete data on effacacy, Which directly or indirectly make us come back to square one where we are still not safe from pandemic.
It is really tough to find out the efficacy rate of vaccine with the observations of only 76 volunteers. Exposure of drug or vaccine is as important as the other phases, because everyone's body may not respond in same manner to the drug or vaccine.

Some international experts have also questioned to the speed at which Russia has approved its vaccine.
"Normally you need a large number of people to be tested before you approve a vaccine," these are the exact words of Peter Kremsner of the University Hospital in Tuebingen, Germany, who is currently testing CureVac's coronavirus vaccine in clinical trials.
Duncan Matthews, a professor of intellectual property law at Queen Mary University of London, said the vaccine is welcomed but safety must be the priority.

The U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have fast-track approval procedures for emergency humanitarian use and need to see evidence that Russia is adopting an equally prudent approach. Statement made by Duncan Matthews.

More than 100 possible vaccines are being developed around the world to try to stop the COVID-19 pandemic. At least four are in final Phase 3 human trials, according to World Health Organization data.
So ultimately all these experts on the pannel are on the same page, they are concered about the efficacy of the drug and they doubt it beacuse its approved just by the observations received from phase 1 and phase 2, total 76 volunteers.

The above link shows the registered clinical trial of sputnik V by Russia, phase 1 and phase 2:

https://clinicaltrials.gov/ct2/show/study/NCT04436471