New Studies Highlight Promising Candidates For Second-Generation Covid-19 Vaccines

The first generation of Covid-19 vaccines has performed more spectacularly than we ever could have hoped. But as more variants of SARS-CoV-2 emerge that spread faster and hit harder than their predecessors, it has become clear that the mRNA vaccines created by Pfizer and Moderna and adenovirus vaccines of AstraZeneca might not be enough to stem the incoming tide. While distribution of these vaccines should continue full speed ahead, the time is ripe for us to take a step forward and ask, what’s next?

Second-generation Covid-19 vaccines will hopefully build upon the accomplishments of their forebears in a number of ways. Of first and foremost concern is their ability to protect against any current and future variants, no matter how infectious or virulent. They should also continue to reduce viral load and elicit high titers of neutralizing antibodies. And perhaps more importantly, if they’re to play a role in redressing vaccine shortages across the globe, second-generation vaccines should be cheap and convenient to produce and administer en masse.

Two subunit vaccines, only recently brought to our attention by a pair of just published research papers, are contenders that have shown particular promise in animal models. Unlike vaccines that use live virus to initiate immunization, subunit vaccines—such as those available for hepatitis B and the human papillomavirus (HPV)—are loaded with specific bits of the virus particle, which being only fragments usually require an adjuvant, or booster shot, to amplify the subsequent immune reaction. While other vaccine types can cause complications or adverse effects in people with chronic immunodeficiencies, nearly everyone can withstand the immune response a subunit vaccine triggers—a general level of tolerance suited to epidemics of global proportions.

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Originally published on Forbes (July 20, 2021)

© William A. Haseltine, PhD. All Rights Reserved.