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Researchers publish first data on coronavirus vaccine approved by Russia.

The coronavirus vaccine approved for use in Russia appears safe and triggered immune responses in tested adults, although the shot may not be as potent as those being advanced by Moderna, Pfizer and AstraZeneca, according to data published Friday in The Lancet.

The vaccine, developed by Moscow's Gamaleya Research Institute, stimulated antibodies capable of neutralizing the virus at levels matching what's found in patients who have recovered from COVID-19 — a sign it could prevent disease. However, without larger and longer trials measuring cases in vaccinated people against those receiving a placebo, it's unclear whether Gamaleya's vaccine works.

One advantage of the Russian vaccine is that it can be distributed in a freeze-dried form that doesn't require freezing, which could make it more useful in poorer countries with fewer healthcare resources. Wealthy nations are jockeying for position to lead the global response to COVID-19, and this vaccine was touted by Russia as a symbol of its scientific achievement.

The Russian Ministry of Health's decision to approve Gamaleya's vaccine before researchers from the institute could publish data invited skepticism around the world. Their article in The Lancet should help reassure public health authorities that, at a minimum, the vaccine isn't causing commonly occurring severe adverse events.

None of the vaccines in late-stage trials have been proven to prevent disease. That is the goal of the massive Phase 3 trials now underway from Moderna, Pfizer and its partner BioNTech, and AstraZeneca and the University of Oxford.

The Gamaleya researchers acknowledge that the levels of "neutralizing antibodies" — those that bind to the virus and prevent it from entering cells or replicating — were below that of the rivals now in Phase 3. However, matching levels seen in the blood of recovered patients suggests it could prove effective to some degree.

The data are complicated by the study's design, however. Gamaleya's vaccine, like others, uses a uninfectious adenovirus as a delivery vehicle for the gene encoding the SARS-CoV-2's characteristic spike protein. These types of "vectors," though, can be destroyed by the body's immune system before they're able to do their job.

Immune cells can learn how to do this by exposure to the vector, limiting such vaccines to a single administration, rather than the two-shot, or prime-boost, vaccinations of other types of shots.

Gamaleya's researchers used two different adenoviruses to get around this problem. Some subjects in their trial were injected with a version of the vaccine using one or the other, and some were injected with both, three weeks apart. Further complicating the results, some were given a frozen version and some were given a freeze-dried version.

The two-dose regimen resulted in the strongest response, similar to findings from early-stage studies of vaccines now in large Phase 3 studies.

A study of Gamaleya's vaccine in 40,000 people is now being launched. Commenting on the results, Naor Bar-Zeev and Tom Inglesby of Johns Hopkins University noted the small trial had enrolled military personnel, which may have generated strongern data than a broader study because younger patients have more robust immune systems.

Moreover, the trial had more men than women and enrolled mostly White subjects, which means more research is needed to get a clearer idea of how the vaccine works in the broader population, the Johns Hopkins scholars wrote.

However, they praised Gamaleya's research for having come up with a freeze-dried formulation.

"A [freeze-dried] formulation could mean stability within the existing global vaccine refrigerated cold chain that is needed to maintain vaccine efficacy from factory to recipient, a hurdle other vaccines are yet to address," they wrote. "Although more costly to produce at scale, product stability will maximize reach in remote terrain, a must if universal and equitable coverage is to be achieved."

The Gamaleya researchers wrote that the freeze-dried formulation was developed "for vaccine delivery to hard-to-reach regions of Russia." However, global public health authorities may find this or other similar formulations more attractive than the leading Western vaccines for distribution to many poorer and remote countries.

Author: Jonathan Gardner


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