Video report by ITV News Correspondent Juliet Bremner
Preliminary results from Russian coronavirus vaccine trials suggest the candidates who took doses experienced no serious adverse side effects and that it was effective.
The trial results, published in the Lancet, found the vaccine did cause the body to develop antibodies to Covid-19.
Results from two early-phase non-randomised vaccine trials on 76 people indicate that two versions of a two-part vaccine have a "good safety profile" with no serious side effects.
The Lancet also cited that those who tried the vaccine did develop an antibody response within 21 days.
The paper reports the findings from two small trials that lasted 42 days in total.
Researchers did, however, note a number of limitations to their study - including that it had a short follow-up.
It was also a small study, while some parts of the trials included only male volunteers, and there was no placebo or control vaccine.
Scientists also noted 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.
The vaccine is based on weakened versions of adenoviruses - 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.
According to the study, both vaccine formulations that were trialled were safe over the 42-day study period and were 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 two trials produced antibodies.
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."
“This provisional licensure requires a large-scale study, allows vaccination in a consented general population in the context of a phase three 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 next phase, phase three of the clinical trial, plans to include 40,000 volunteers from different age and risk groups.