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Delta variants could further prolong the Covid pandemic

While restrictions are eased and borders are opened across the globe, new research shows that the emergence of the Delta and “Delta Plus” variants of SARS-CoV-2 could result in the pandemic being prolonged further if strategic “heterologous vaccination” is not put in action.

The researchers studied the mutations present in Delta and Delta Plus, concluding that the Delta was immune to one-in-four antibody groups produced by natural immunity and vaccines, with Delta Plus being resistant to one out of two.

“It is conceivable that by fusing cells in the respiratory tract, the Delta variant may spread more efficiently and induce more damage. This could contribute to a more severe course of COVID-19,” explained study lead author Arora Prerna.

However, it was discovered that individuals vaccinated with a single dose of both Oxford-AstraZeneca and BioNTech-Pfizer showed significantly higher immunity than those with two doses of Oxford-AstraZeneca.

The research team used cell culture experiments to come to this conclusion, finding that Delta is most resistant against the monoclonal antibody balmlanivimab, with Delta Plus being resisting to both balmlanivimab and etesimab. As a result, Delta and Delta Plus were less well inhibited by antibodies from vaccinated and infected individuals when compared to the original COVID-19 virus, resulting in the rapid spread of the variants.

“This means that vaccination likely confers comparable protection against Delta and Delta Plus and that Delta Plus is not significantly more dangerous than Delta,” explained Stefan Pöhlmann.

Across Europe, BioNTech-Pfizer is the most commonly used vaccine, followed by Oxford-AstraZeneca. In Germany, rare side effects associated with Oxford-AstraZeneca have resulted in the recommendation that BioNTech-Pfizer is used as the second vaccination dose to anyone who has already received a dose of Oxford-AstraZeneca, a strategy known as ‘heterologous vaccination’

“Our results are consistent with the observation that vaccination efficiently protects against the development of severe disease after infection with the Delta variant, but frequently fails to completely suppress infection,” said Stefan Pöhlmann.

“In light of the efficient protection against severe disease, the goal continues to be a high vaccination rate. This can prevent the health care system from being overwhelmed in case of increased spread of Delta and closely related viruses during the winter months.” 

“Our studies show that heterologous vaccination induces significantly more neutralizing antibodies to Delta than two vaccination shots with Oxford-AstraZeneca. Individuals who have received such a heterologous vaccination may have a very good immune protection against Delta and Delta Plus,” said Markus Hoffmann.

The study was conducted through a collaboration between the German Primate Center’s Leibniz Institute for Primate Research in Göttingen, the Hannover Medical School, The University of Göttingen Medical Center, and the Friedrich-Alexander University of Erlangen-Nürnberg.

The research is published in the journal Cell Reports

By Calum Vaughan, Staff Writer

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