It’s difficult to know how close the world is coming to an effective vaccine that will inoculate against the new coronavirus, but the pace for production and approval has been quickened dramatically, according to University of Idaho professor and microbiologist Tanya Miura.
Speaking in a virtual conference as part of the UI’s Malcolm M. Renfrew Interdisciplinary Colloquium Tuesday, Miura said researchers are investigating numerous strategies for developing an effective vaccine and some are already in phase-3 clinical trials.
Miura said vaccines operate by leveraging the body’s adaptive immune response to “train” lymphocytes and antibodies to attack invasive pathogens like viruses. Antibodies are small proteins that recognize and bind with specialized proteins on viruses called antigens — neutralizing their ability to invade host cells and flagging them for destruction by search-and-destroy lymphocytes called cytotoxic T cells.
The new coronavirus — also called SARS-CoV-2 — is surrounded by spike-like antigens that allow it to attach to a host cell, penetrate it and hijack it to produce viral material. Infected cells will then produce their own spikes. Miura said antibodies and T-cells can be specially trained to respond to cells with these spikes to neutralize or destroy the pathogen or infected cell. She said there are a number of different kinds of vaccines designed to trick the body into developing a response like it would for a true virus.
Among numerous kinds of vaccines being tested are the traditional approach of exposing patients to a deactivated or weakened version of the virus and another method where viral genetic material is isolated, encased in a membrane and injected into a patient. She said pharmaceutical companies Pfizer and Moderna have begun phase-3 clinical trials for the latter and the results have been promising.
“In the trials that have been published so far, they induce both T cell and antibody responses,” Miura said.
Miura noted the novel coronavirus has mutated since the pandemic began and the mutated strain has become the dominant version of the virus in many regions. However, she said a recent study comparing the two strains found differences between them to be negligible both in terms of severity of infection and resistance to a vaccine.
“They compared the (mutated) virus with the original virus and they showed that they’re neutralized by antibodies equally well,” she said. “So any vaccines that were designed against this original virus should still provide protection against the new strain that has taken over.”
Miura said there are a number of other obstacles to the production and distribution of an effective vaccine, including human behavior. She said scientists estimate between 50 percent and 80 percent of the population must be inoculated to provide herd immunity and change the course of the pandemic. According to surveys issued by the Pew Research Center, 72 percent of respondents in May said they were likely to get vaccinated if a vaccine were to become available, and just 51 percent said the same thing in September.
Further complicating matters, she said a vaccine may not even provide “sterilizing immunity” that prevents a person from being infected or transmitting the disease in the first place, but may merely lessen the toll it takes on an individual.
“It’s very likely we’ll end up with a vaccine that reduces the severity of the disease, reduces your chances of dying from COVID, but doesn’t stop transmission,” Miura said. “In that case there’s no herd immunity even on the table.”
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