Early results of Russian Covid-19 vaccine trials suggest candidates are safe

EMBARGOED TO 0001 SUNDAY AUGUST 9 File photo dated 05/10/09 of a nurse preparing to give a patient a vaccine. Just over half
EMBARGOED TO 0001 SUNDAY AUGUST 9 File photo dated 05/10/09 of a nurse preparing to give a patient a vaccine. Just over half the UK population would be certain or very likely to have a vaccine against coronavirus, with "damaging" misperceptions influencing people's intentions, research suggests.

Preliminary results from Russian coronavirus vaccine trials suggest the candidates led to no serious adverse events and also elicit an antibody response.

Results from two early-phase non-randomised vaccine trials in a total of 76 people indicate that two formulations of a two-part vaccine have a good safety profile with no serious adverse events detected over 42 days.

The findings, published in the Lancet, also found the candidates induced an antibody response in all participants within 21 days.

Secondary outcomes from the trial suggest the vaccines also produce a T-cell response within 28 days.

The paper reports findings from two small phase 1/2 trials lasting 42 days.

One looked at a frozen formulation of the vaccine, and another involving a lyophilised (freeze-dried) formulation.

It is envisaged that the frozen formulation will be for large-scale use, using existing global supply chains for vaccines.

The freeze-dried formulation was developed for hard-to-reach regions as it is more stable and can be stored at 2-8C, the researchers say.

The two-part vaccine includes two adenovirus vectors which have been modified to express the SARS-CoV-2 spike protein.

These types of vaccines are based on weakened versions of adenoviruses which are a group of viruses that typically infect membranes of the eyes, respiratory tract, urinary tract, intestines and nervous system, and include the common cold.

Lead author Dr Denis Logunov, of the N F Gamaleya National Research Centre for Epidemiology and Microbiology in Russia, said: “When adenovirus vaccines enter people’s cells, they deliver the SARS-CoV-2 spike protein genetic code, which causes cells to produce the spike protein.

“This helps teach the immune system to recognise and attack the SARS-CoV-2 virus.

“To form a powerful immune response against SARS-CoV-2, it is important that a booster vaccination is provided.”

The trials took place in two hospitals in Russia and were open-label and non-randomised – meaning participants knew they were receiving the vaccine and were not assigned by chance to different treatment groups.

The trials involved healthy adults aged 18-60, who self-isolated as soon as they were registered for the trial and remained in hospital for the first 28 days of the trial.

The frozen vaccine (Gam-Covid-Vac – known as Sputnik V) was trialled in the Burdenko Hospital in Moscow, and involved both civilian and military volunteers.

The freeze-dried vaccine (Gam-Covid-Vac-Lyo) trial took place at Sechenov University in the Russian capital, and all volunteers were civilians.

In phase 1 of each trial, participants received one component of the two-part vaccine on day zero.

In phase 2, which started no earlier than five days after the phase 1 trial, participants received the full two-part vaccine – they were given a prime vaccination with the rAd26-S component on day 0, followed by a booster vaccination with rAd5-S component on day 21.

There were 20 participants each in the frozen and freeze-dried vaccine groups.

In order to compare post-vaccination immunity with natural immunity, the authors obtained convalescent plasma from 4,817 people who had recovered from mild or moderate Covid-19.

According to the study, both vaccine formulations were safe over the 42-day study period and well tolerated.

The most common adverse reactions were mild and included pain at the injection site, high temperature and headache.

All participants in the phase 2 trials (40 participants) produced antibodies against the SARS-CoV-2 spike protein.

Neutralising antibody responses also occurred in all 40 participants in the phase 2 trials by day 42.

The authors say that despite there being neutralising antibody responses against the adenovirus vectors, the antibody response to the SARS-CoV-2 spike protein was not affected.

They suggest this means using different adenovirus vectors is an effective approach to elicit a robust immune response and to overcome the immune reaction to the first viral vector, but note that more research is needed to confirm this.

The researchers note a number of limitations to their study, including that it had a short follow-up, it was a small study, some parts of the phase 1 trials included only male volunteers, and there was no placebo or control vaccine.

They further note that despite planning to recruit healthy volunteers aged 18–60, in general, their study included fairly young volunteers, on average in their 20s and 30s.

Professor Alexander Gintsburg, also of the N F Gamaleya National Research Centre for Epidemiology and Microbiology in Russia, said: “Pre-clinical and clinical studies have been done, which has made it possible to provisionally approve the vaccine under the current Decree of the Government of the Russian Federation of April 3 2020 no 441.

“This provisional licensure requires a large-scale study, allows vaccination in a consented general population in the context of a phase 3 trial, allows the vaccine to be brought into use in a population under strict pharmacovigilance (drug safety measures), and to provide vaccination of risk groups.”

The phase 3 clinical trial of the vaccine plans to include 40,000 volunteers from different age and risk groups.

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