30 agosto, 2021

Russia’s Sputnik V protects against severe COVID-19 from Delta variant, study shows

Russia’s Sputnik V vaccine is holding up well against the Delta variant, a paper posted yesterday on the preprint server medRxiv shows. The study of nearly 14,000 people showed the two-dose vaccine reduces the risk of hospitalization with COVID-19 by 81% and helped prevent severe lung injury.

Surges of COVID-19 in many countries and an increasing number of “breakthrough” cases in vaccinated people have raised concerns that vaccines don’t protect as well against Delta as against earlier strains, or that vaccines’ protection may be short-lived. Israeli data on breakthrough infections point to limited protection offered by messenger RNA (mRNA) vaccines; however, a recent study of the Pfizer-BioNTech and AstraZeneca vaccines found the two were largely effective against Delta.

Like other cities in Russia, St. Petersburg has set up triage centers, where patients with a confirmed SARS-CoV-2 diagnosis and COVID-19 symptoms receive a brief physical examination and a low-dose computed tomography (CT) scan of their lungs to determine whether they need hospitalization. A team led by epidemiologist Anton Barchuk of the European University at St. Petersburg asked doctors at two such centers to inquire about patients’ vaccination status. (They did not ask which of the vaccines available in Russia a patient had received, but government data suggest about 96% of vaccine recipients in St. Petersburg got Sputnik V.) The analysis included 13,894 patients, 1291 of whom were fully vaccinated. Of the participants, 495 were referred to hospital.

Sputnik V offered completely vaccinated patients—who had had their second shot at least 2 weeks before coming to the triage center—81% protection against being hospitalized, the study found. (The effectiveness was slightly better in women than in men, 84% versus 76%.) The study included too few people to detect a statistically significant benefit of partial vaccination. “Our data confirm that the benefits of vaccination include attenuating disease severity in breakthrough cases,” Barchuk says.

Even though the study did not confirm which viral variants patients had, Russian health authorities attributed 95% of COVID-19 cases to the Delta variant in July and August, when the study ran.

The researchers also found that Sputnik V had 76% effectiveness at protecting against severe lung injury from COVID-19, meaning more than 50% of the lung is visibly affected on a CT scan. “We were able to get this rather unique data because no one in the world seems to perform as many CT scans for patients with mild disease as Russia does,” Barchuk says.

The study did not measure protection against SARS-CoV-2 infection or mild forms of disease. But the authors’ calculations, based on city-level vaccination numbers, offer an indirect estimate of effectiveness against symptomatic disease of about 50%.

John Moore, an immunologist at Weill Cornell Medicine, says the study results “seem credible and also consistent with expectations.” He adds that 81% protection against hospitalization is a bit lower than the recent effectiveness of mRNA vaccines seen in the United States and elsewhere, but still “very good.”

Sputnik V, developed by the ‎Gamaleya National Center of Epidemiology and Microbiology, works in the same way as the vaccines produced by AstraZeneca and Johnson & Johnson (J&J): A nonreplicating adenovirus delivers a bit of DNA coding for the SARS-CoV-2 spike protein into the recipient’s cells. But whereas AstraZeneca uses the same adenovirus for both doses, Sputnik V uses two different types, to prevent antibodies against the first dose from rendering the second one ineffective. (J&J only uses one dose; a trial of a two-dose regimen is ongoing.)

“The Sputnik V design principle has always been considered a good one, better in my view than the AstraZeneca/Oxford and J&J vaccine designs, assuming J&J soon moves to two doses,” Moore wrote in an email to Science. “The concern some people have expressed is the validity of data published under the control of the Russian government.” The St. Petersburg study was done independent of the government and Gamaleya.

Sputnik V is now authorized in 69 countries, and some 10 million to 15 million doses are produced monthly, according to media reports. The European Medicines Agency and the World Health Organization (WHO) are still reviewing the vaccine. WHO authorization would mean the vaccine can be distributed under the COVID-19 Vaccines Global Access Facility, a program to give low- and middle-income countries access to COVID-19 vaccines. (A WHO spokesperson said this month it does not have a possible decision date.)

But the global rollout has been delayed because the Russian Direct Investment Fund, the government organization that funded the vaccine’s development and markets it internationally, failed to deliver second doses to Argentina, the Philippines, and other countries that had received shipments of the first doses. The fund said it would be able to resolve the shortages in August.

The new study’s encouraging results are likely to highlight those logistical troubles, says Judy Twigg, a Virginia Commonwealth University professor of political science who follows the development of Sputnik V. “Russia’s vaccine diplomacy has been breaking down not because of issues with the perceived quality of the product, but instead due to broken promises for its delivery,” Twigg says.

In Russia, which authorized Sputnik V more than 1 year ago and started mass vaccinations in January, the rollout has progressed slowly: About 22% of the country’s population is fully vaccinated, according to government figures, despite vaccine mandates for certain professions in many regions. Surveys suggest hesitancy is fueled by distrust of the government and conflicting messages from state media. Russia is now in the grip of its third wave of infections, with daily new cases at more than 20,000.

Only a handful of studies of Sputnik’s effectiveness have been done. Barchuk hopes more will follow, especially given the global spread of the Delta variant. “Unfortunately, there is an evident shortage of studies for Sputnik compared to other vaccines,” he says, “which only adds to controversies around this vaccine, both in Russia and globally.”

Créditos: Comité científico Covid

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