Sputnik V

Sputnik V
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The Gam-COVID-Vac – trade-named Sputnik V (V for vaccine) – is a COVID-19 vaccine developed by the Gamaleya Research Institute of Epidemiology and Microbiology, and registered on 11 August 2020 by the Russian Ministry of Health. Gam-COVID-Vac was approved for distribution in Russia, despite having been tested only in a small number of people, in early-stage clinical trials that lasted two months, normally a process requiring a year or more of clinical assessment for proof of vaccine safety and efficacy against viral disease.

The quick approval of Sputnik V was initially criticised as premature, in order to claim being the first country to produce a COVID-19 vaccine. Protests developed in the international scientific community over announcement of the vaccine registration, mainly because there was initially no publication of results from clinical trials on Sputnik V.

Phase III trials

Although Phase I-II results were eventually published on 4 September 2020, the pivotal Phase III trial – a necessary scientific step to prove vaccine safety and efficacy in thousands of individuals – had not yet been completed in its entirety. At the time of Sputnik V registration in Russia after early trials, several other vaccine candidates were already being evaluated in interventional Phase III trials involving thousands of participants. In most countries following guidelines of the World Health Organization, vaccine candidates are not approved or licensed until safety and efficacy data from Phase III trials are assessed and confirmed internationally by regulators. In December 2020, the Gamaleya Research Institute published preliminary data on 22,714 participants of its phase III trials. The study is a randomised, double-blind, placebo-controlled, multi-centre clinical trial involving 40,000 volunteers and is scheduled to run until May 2021.

Two-vector vaccine

Sputnik V is a viral two-vector vaccine based on two human adenoviruses — a common cold virus — containing the gene that encodes the spike protein of SARS-CoV-2 to stimulate an immune response. The recombinant adenovirus type-26 (rAd26, component I) and adenovirus type-5 (rAd5, Component II) are both used as vectors in the vaccine. Both of them are administered intramuscularly: the rAd26 based vaccine is used on the first day and the rAd5 vaccine is used on the 21st day to boost response.

Sputnik V can be formulated as frozen (storage temperature is −18 °C) and freeze-dried "Gam-COVID-Vac-Lyo" (storage temperature is 2–8 °C) dosage forms. The first formulation was developed for large-scale use, it is cheaper and easier to manufacture. The production of a lyophilised formulation takes much more time and resources, although it is more convenient for storage and transportation. It is then diluted before injection.

In Violation of the Most Important Testing Standards

A group of scientists from leading Russian universities has blasted the development process of Russia’s Sputnik V coronavirus vaccine as “completely unacceptable” and “ridiculous” in an open letter raising new concerns over a lack of sufficient data on its safety and effectiveness.

The race-like atmosphere made the vaccine developers “hostage” to Russia’s political goals, they said. “It threatens the benign testing of the vaccine and, therefore, poses a threat to the health of Russians.”

The experts said Russia’s state-run Gamaleya Research Institute, which is developing the vaccine, has ignored requests to share data — despite public pledges to do so — and have raised fresh fears over political meddling and a string of alleged shortcomings in the vaccine research.

The group heavily criticized Russia’s decision to start a mass vaccination program — which is officially only open to healthcare workers and teachers under the age of 60 with no underlying health conditions — while large-scale medical trials were still at such an early stage.

“This completely unacceptable — even ridiculous — political action to create a competition between vaccines is in violation of the most important testing standards,” wrote the scientists — led by Vasiliy Vlassov, an esteemed epidemiologist at Moscow’s Higher School of Economics, along with Olga Rebrova, a professor at the Russian National Research Medical University, and Valery Aksyonov, scientific editor of Bionica Media.

Other Russian doctors told The Moscow Times they were highly skeptical about taking the vaccine.

Combining with AZD1222

On 11 December 2020, AstraZeneca announced a clinical trial programme to assess safety and immunogenicity of a combination of AZD1222 and Sputnik V, developed by the Russian Gamaleya Research Institute. Dr Zoltán Kis, Research Associate at the Future Vaccine Manufacturing Hub, Imperial College (London), said:

“Both the AstraZeneca/Oxford vaccine candidate and the Sputnik V vaccine are adenovirus vectored vaccines and both deliver genetic instructions for the cells of the body to produce the Spike protein of SARS-CoV-2. The AZD1222 vaccine candidate is based on a chimpanzee adenovirus and the Sputnik V vaccine is based on a human adenovirus, thus the vectors (or carriers) of these two vaccines are slightly different.

“The immune system of the human body can generate an immune response against the adenoviral vector itself, thus if a second dose of the same adenovirus vectored vaccine is delivered, the immune system could destroy the vector, before the payload of the vaccine is delivered, therefore reducing the efficacy of the second vaccine dose. On the other hand, if the vector of the second (booster) dose of the vaccine is different from the vector of the first (prime) dose, the immune system will be less likely to destroy the vector of the vaccine, thus the efficacy of the heterologous boosting vaccination could be increased, compared to the situation where both the prime and boost doses were of the same vector type. Therefore, the reason why heterologous boosting could increase vaccine efficacy, is that the (partial) destruction of the second vaccine dose by the immune system can be avoided and because both vaccines contain instructions for producing the same antigen.

“Furthermore, having the possibility of combining these two vaccine types would allow for greater flexibility in the vaccination programs. This could lead to greater accessibility to vaccines, thus increasing the rate and scale of Covid-19 vaccination coverage.

“For these reasons, the news regarding clinical trials of this heterologous boosting Covid-19 vaccination is a promising one.”

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References

This page imported content from Wikipedia on 31 December 2020.
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