Tag: Sputnik V

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Half Dose of COVID Booster Yields Similar Immune Response to Full One

On By ModernMedia
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Reducing the dose of a widely used COVID booster vaccine produces a similar immune response in adults to a full-dose with fewer side effects, according to a new study published in The Lancet Regional Health – Western Pacific. The research found that a half dose of a Pfizer COVID booster vaccine elicited a non-inferior immune response to a full dose in Mongolian adults who previously had AstraZeneca or Sinopharm COVID shots. But it found half-dose boosting may be less effective in adults primed with the Sputnik V COVID vaccine. 

The research, led by Murdoch Children’s Research Institute (MCRI) and the National Centre for Communicable Diseases in Mongolia, is part of an international clinical trial investigating the different COVID booster shot approaches to help guide future vaccination strategies. 

The first batch of findings, and involving 601 participants over 18 years old from Mongolia, reports on the initial responses seen 28-days after vaccination. The study is the first of its kind to assess and compare COVID-19 vaccines widely used in low- and middle-income countries.

MCRI Professor Kim Mulholland, who also sits on the WHO SAGE committee, said the study found that fractional doses elicited an immune response that was non-inferior to a full dose with fewer side effects and was less costly.

“Fractional dosing may improve COVID booster acceptability and uptake and reduce the per-dose cost of COVID-19 booster programs,” he said. “Policymakers and immunisation advisory committees can draw upon this data to make flexible boosting schedules decisions.”

The study found that participants receiving a half dose reported fewer local reactions than those receiving full doses (60% versus 72%) including less pain and tenderness. They also reported fewer systemic reactions (25% vs 32%) including less fevers, vomiting, diarrhoea and headaches. 

The cohort will be followed up at six and 12 months with the data to answer key questions on other aspects of the immune response including the rate of waning and breakthrough infections. 

Source: Murdoch Children’s Hospital

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Review Finds Little, if Any, Difference in Safety among COVID Vaccines

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Covid vaccines
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A Cochrane review of all the evidence available from randomised controlled trials of COVID vaccines up to November 2021 has concluded that most protect against infection and severe or critical illness caused by the virus. In addition, the Johnson and Johnson vaccine and the Cuban Soberana 2 vaccine “probably” reduced all-cause mortality.

The independent, international expert reviewers also found that there was little or no difference between the number of people experiencing serious side effects after vaccination compared to those who were unvaccinated.

The researchers, led by Isabelle Boutron, Professor of Epidemiology at Université Paris Cité and Director of Cochrane France, analysed published data from 41 randomised controlled trials of 12 different COVID vaccines, involving 433 838 people in various countries around the world. They assessed the certainty of the evidence and the risk of bias in the different studies.

The trials compared COVID vaccines with placebo, no vaccine, or each other, and were published before 5 November 2021. Most trials were no longer than two months in length.

The review found that the following vaccines reduced or probably reduced the risk of COVID infection compared to placebo: Pfizer/BioNTech, Moderna, CureVac COVID-19, Oxford-AstraZeneca, J&J, Sputnik V (Gam-COVID-Vac), Sinopharm (WIBP CorV and BBIBP-CorV), Bharat (Covaxin), Novavax and Soberana 2 (Finlay-FR-2). The following reduced or probably reduced the risk of severe or critical disease: Pfizer/BioNTech, Moderna, Janssen, Sputnik V, Bharat and Novavax. In addition, the J&J and Soberana 2 vaccines probably decreased the all-cause mortality risk. There were very few deaths recorded in all the trials and so evidence on mortality for the other vaccines is uncertain.

For most of the vaccines, vaccinated individuals reported more localised or temporary side effects compared no-treatment or placebo groups. These included tiredness, headache, muscle pains, chills, fever and nausea. With respect to the very rare side effects associated with some vaccines such as thrombosis, the team found that the reporting of these events was inconsistent, and the number of events reported in the trials was very low.

Given the evidence of efficacy of these vaccines, the researchers question whether further placebo-controlled trials are ethical. They suggest that further research compares new vaccines with those already in use.

Source: Wiley

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South African Variant Escapes Sputnik Vaccine

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A study on COVID variants using in vitro tests, available on the preprint server medRXiv, has shown that the South African variant escapes the Sputnik V vaccine.

This study is the first of its kind to show Sputnik V vaccine recipients had reduced neutralising capacity against the B.1.351 and E484K mutant spikes.

When it comes to vaccine design, the most effective vaccines use a stabilised form of the spike protein, while others use the wildtype spike, protecting against severe disease but not infection because of lower levels of neutralising antibodies. A number of SARS-CoV-2 variants of concern (VOC) have mutations on the spike protein, or the E484K mutation, which allows it to escape vaccines and prior immunity. 

In South Africa, where 93% of infections are due to B.1.351, the AstraZeneca vaccine, based on the wild-type spike, failed to prevent mild-to-moderate COVID. The Sputnik V or Gam-COVID-Vac vaccine is also based on the wild-type spike. Interim Phase 3 trial results reported an efficacy of 92%, but this excludes current variants and any lineage containing E484K. 
The current study examined serum neutralisation activity in samples obtained from 12  recipients of the Sputnik V vaccine in Argentina. This country has already detected many independent variants with E484K, with or without N501Y substitutions.

The researchers found that pseudoviruses bearing either the wildtype D614G spike, and the B.1.1.1.7 spike were effectively neutralised by the vaccine sera, in live virus plaque reduction neutralisation assays. The geometric mean titer of neutralising titers was 49, similar to that of the phase III trial.

However, these sera showed moderate to a marked reduction in neutralisation titers against spike protein bearing E484K, and the UK variant. Even at the highest serum concentration used, 9 of the 12 serum samples could not inhibit 50% of B.1351 viral particles, and only half the sera did so against the E484K mutant.

The researchers concluded that, relative to the wildtype spike virus neutralising titers, were reduced by seven-fold against the B.1.351 lineage and three-fold against the E484K spike. They also found that the VOCs with the different spikes showed different modes of escape from antibody-mediated neutralisation by sera elicited by the Sputnik V vaccine. This means that resistance to neutralisation offered by the South African variant occurs by a different mechanism than that of the E484K mutant.

The UK VOC has low resistance to pre-existing or vaccine-induced antibodies, but the B.1.351 variant shows marked resistance. In fact, 8 of 12 samples were unable to reach IC90 at the highest possible serum concentration.

One neutralised the UK variant but none of the other three variants. These findings are of particular concern because all three VOCs carry the N501Y RBD substitution that confers increased affinity for the ACE2 receptor.

This resistance is competitive and is not present at higher serum concentrations. However, this is not true for the mutations in the B.1.351 variant, which escapes neutralisation with undiluted serum.

Though the Sputnik V vaccine likely protects against severe COVID from VOCs, it is troubling that B1.351, as well as all E484K-bearing mutants, is resistant to neutralisation by sera elicited by this vaccine.

However, antibody functions may be different in vivo, and this study does not cover cell-mediated immunity to multiple antigen sites.
“Taken together, our data argue that surveillance of the neutralizing activity elicited by vaccine sera will be necessary on an ongoing basis,” the authors wrote.

The knowledge of which variants can still spread among vaccinated and naturally immune individuals will help decide how to contain them with vaccine upgrades.

Source: News-Medical.Net

Preprint information: Ikegame, S. et al. (2021). Qualitatively distinct modes of Sputnik V vaccine-neutralization escape by SARS-CoV-2 Spike variants. medRxiv preprint. doi: https://doi.org/10.1101/2021.03.31.21254660. https://www.medrxiv.org/content/10.1101/2021.03.31.21254660v2