Russia’s controversial vaccine is 91.6% effective against symptomatic coronavirus, research suggests.
In August 2020, the nation became the first in the world to approve a jab against the infection after less than two months of human testing.
A lack of efficacy data prompted some experts to warn rolling out a “less than safe and effective” vaccine could cause “collateral damage” that would exacerbate the world’s “current problems insurmountably”.
In the latest development, an ongoing phase 3 trial – typically the last stage before seeking approval – has demonstrated administering the two-dose vaccine 21 days apart was 91.6% effective against symptomatic coronavirus when tested on nearly 20,000 adults.
The results, also published in The Lancet, further suggest the jab was 91.8% effective among the more than 2,000 participants over 60.
Elderly people tend to have a more subdued immune response following immunisation. Germany’s vaccine regulator recently advised people over 65 bypass the AstraZeneca-University of Oxford jab due to a lack of efficacy data, a move that has been largely criticised.
“Our interim analysis of the randomised, controlled, phase 3 trial of Gam-COVID-Vac [also known as Sputnik V] in Russia has shown high efficacy, immunogenicity and a good tolerability profile in participants aged 18 years or older,” said co-lead author Dr Inna Dolzhikova, from the Gamaleya National Research Centre for Epidemiology and Microbiology in Russia.
President Vladimir Putin announced in August the jab was officially registered with the Russian Health Ministry after it brought about “stable” immunity “quite effectively”.
In response to the phase 3 results, Professor Ian Jones from the University of Reading and Professor Polly Roy from the London School of Hygiene & Tropical Medicine wrote in The Lancet: “The development of the Sputnik V vaccine has been criticised for unseemly haste, corner cutting and an absence of transparency.
“But the outcome reported here is clear and the scientific principle of vaccination is demonstrated, which means another vaccine can now join the fight to reduce the incidence of COVID-19 [the disease caused by the coronavirus].”
It is unclear when the scientists behind the vaccine may seek regulatory approval in the rest of the world.
In the UK, three coronavirus vaccines are approved: Pfizer-BioNTech, AstraZeneca-University of Oxford and Moderna.
Globally, 64 jab candidates are said to be under development, with 13 in phase 3 trials. A further 173 vaccines are in a pre-clinical stage.
“Stopping the COVID-19 pandemic requires the introduction of different vaccines based on different mechanisms of action to cover diverse global health demands,” said co-lead author Dr Denis Logunov.
“Our vaccine, along with other SARS-CoV-2 [coronavirus] vaccines, helps to diversify the world SARS-CoV-2 vaccine pipeline.”
Sputnik V was tested in an earlier-stage trial as both a frozen and freeze-dried formula.
The formulation used in the ongoing phase 3 study “requires storage at -18C (-0.4F)”, however, “storage at 2-8°C (35.6-46.4F) has also been approved”.
The technology used to develop the Pfizer-BioNTech and Moderna jabs means they must be kept at around -80C (-112F) and -20C (-4F), respectively.
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Speaking of the Sputnik V vaccine, Dr Alexander Edwards from the University of Reading said: “These viral vaccines are relatively stable (no need for storage at extreme temperature), but do have to be ‘grown’ in bioreactors so we can expect major expansion of the global capacity for manufacturing these adenovirus medicines.
“Manufacturing may remain a bottleneck for months to come, so the more vaccines available, the better for global health.
“Pandemic means ‘all’ and the only way to address a global problem is with a global response – sharing data, science, technology and medicines.”
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Nearly 21,000 adults were recruited into the Moscow-based trial between September and November 2020.
The participants were swabbed for the coronavirus at the start of the study and on day 21, when the second dose was administered.
Anyone who developed symptoms – like a fever, cough, or loss of taste or smell – was also tested.
At day 21, 16 people tested positive for the coronavirus out of the more 14,900 adults who received the vaccine (0.1%).
This is compared to 62 incidences among the over 4,900 given a placebo (1.3%), giving an efficacy equivalent to 91.6%.
The scientists stressed that only testing the individuals who developed coronavirus symptoms between the start of the study and day 21 means it is unclear if the vaccine wards off asymptomatic infections, which may play a key role in transmission.
The ongoing study aims to recruit 40,000 participants.
In a second part of the trial, the scientists assessed the vaccine’s potential against moderate or severe coronavirus complications.
At day 21, no moderate or severe incidents had arisen among those given the first dose, compared to 20 cases in the placebo group, “equivalent to an efficacy of 100% against moderate or severe COVID-19”.
The trial was not designed to assess vaccine efficacy after one dose.
Nevertheless, the results “hint to the early onset of a partially protective effect 16-18 days” after the first jab, wrote the scientists.
“From day 15-21, efficacy against moderate or severe COVID-19 was 73.6%,” they added.
The team has recently been given the green light to investigate the vaccine’s effectiveness after just one dose.
A Johnson & Johnson trial demonstrated their vaccine candidate was 85% effective against severe COVID-19 after just one jab, however, the scientists acknowledged efficacy is expected to be even higher following a two-dose regimen.
A relatively small data sub-set suggests two doses of Sputnik V induced a “robust” antibody and T-cell response, both of which are aspects of the immune system.
Just six of the 342 participants who were tested for antibodies did not show signs of the immune-fighting proteins in their blood, which help prevent an infection taking hold.
The scientists said this may be due to the six people being older or having “individual characteristics”, like a suppressed immune system.
They added all the participants were only followed for around 48 days after the first vaccine dose, making the jab’s duration of protection unclear.
When it comes to safety, no serious adverse events were “deemed to be associated with vaccination”.
The majority of the side effects were mild, including flu-like symptoms, injection-site pain and weakness or low energy.
Four deaths have occurred across the trial, none of which have been linked to the vaccine.
The jab was found to be similarly well tolerated among the participants over 60, based on the safety data of more than 1,300 participants.
The two-dose vaccine is made up of two different viruses that can cause colds, but have been modified to express the coronavirus’ spike protein, which it uses to enter cells.
The viruses are weakened, leaving them unable to replicate in human cells or cause disease. The same pathogens have been used in vaccines before, demonstrating the approach’s safety.
Using different viruses for the two doses may “create a more powerful immune response”, minimising the risk the immune system will “develop resistance” to one of the modified pathogens.
The scientists stressed their study’s participants were largely white, with the results not necessarily applying to other ethnicities. Research has repeatedly flagged deaths are higher among non-white people with the coronavirus.
While the trial enrolled people with underlying health issues, “not all risk groups are represented”, added the team.
The scientists stressed the need for trials into vaccine safety and efficacy among people under 18 and pregnant women.
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