In already infected persons, a single dose of the Sputnik V vaccine may be adequate to elicit a significant antibody response against SARS-CoV-2, the virus that causes COVID-19.
QUILMES, ARGENTINA - DECEMBER 29: A nurse shows a box containing the first dose of 'Gam-COVID-Vac' also known as Sputnik V vaccine, against coronavirus, as she prepares to administer it at Isidoro Iriarte Hospital on December 29, 2020, in Quilmes, Argentina. The argentine government begins today the campaign to apply the first 300,000 doses that arrived from Russia.
Sputnik V COVID Vaccine's Single-Dose Triggers Strong Antibody Response
A new study, titled "Sputnik V Vaccine Elicits Seroconversion and Neutralizing Capacity to SARS CoV-2 after a Single Dose," looked into whether a single dosage of Sputnik V vaccine will provide a bigger public health benefit than two doses by protecting a broader population more soon.
Two doses of Sputnik V, a vector vaccine made up of two adenoviruses, were reported to have a 92 percent efficacy against Covid-19 infection in previous experiments.
"Due to limited vaccine supply and uneven vaccine distribution in many regions of the world, health authorities urgently need data on the immune response to vaccines to optimize vaccination strategies," study senior author Andrea Gamarnik of the Fundacion Instituto Leloir-CONICET in Buenos Aires, Argentina, said per Eurekalert.
"The peer-reviewed data we present provide information for guiding public health decisions in light of the current global health emergency," Gamarnik added.
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The evidence from other vaccines, according to the researchers, supports the one-shot technique. Florida News Times said the AstraZeneca vaccine has a 76 percent efficacy after a single dosage, while the Moderna and Pfizer vaccines may produce sufficient protection in previously infected patients after a single dose, with no evident advantage of a second dose.
In 289 healthcare professionals in Argentina, the researchers compared the effects of one and two Sputnik V shots on SARS-CoV-2-specific antibody responses. All participants who had never been infected before developed virus-specific immunoglobulin G (IgG) antibodies three weeks following the second injection.
However, 94 percent of these patients acquired IgG antibodies against the virus within three weeks of getting the initial dose, and 90% exhibited indications of neutralizing antibodies, which prevent viruses from infecting cells.
IgG, Neutralizing Antibody Levels Better After One Sputnik V COVID-19 Dose
In addition, IgG and neutralizing antibody levels in previously infected participants were significantly better after one dose than in completely vaccinated volunteers with no history of infection.
In previously infected individuals, a second dose had no effect on the generation of neutralizing antibodies. Gamarnik said, per Science Blog, the study emphasizes previously infected individuals' powerful response to vaccination. The researcher added that naturally acquired immunity could be significantly improved by a Sputnik V single dose, keeping with other research using mRNA vaccines.
According to the researchers, further research is needed to determine the length of the immune response and how antibody levels relate to vaccine protection against Covid-19.
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