With several companies progressing through Phase III clinical trials, the much-awaited coronavirus vaccines may finally become reality within a few months.
But some scientists question whether these vaccines will produce a strong and long-lasting immunity, especially if they aren't efficient at mobilizing T-cells, the body's defense soldiers.
"When I look at those vaccines there are pitfalls in every one of them," says Deborah Fuller, professor of microbiology at the Washington University School of Medicine. "Some may induce only transient antibodies, some may not be very good at inducing T-cell responses, and others may not immunize the elderly very well."
Generally, vaccines work by introducing an antigen into the body—either a dead or attenuated pathogen that can't replicate, or parts of the pathogen or its proteins, which the body will recognize as foreign. The pathogens or its parts are usually discovered by cells that chew up the intruders and present them to the immune system fighters, B- and T-cells—like a trespasser's mug shot to the police. In response, B-cells make antibodies to neutralize the virus, and a specialized "crew" called memory B-cells will remember the antigen. Meanwhile, an army of various T-cells attacks the pathogens as well as the cells these pathogens already infected. Special helper T-cells help stimulate B-cells to secrete antibodies and activate cytotoxic T-cells that release chemicals called inflammatory cytokines that kill pathogens and cells they infected.
"Each of these components of the immune system are important and orchestrated to talk to each other," says professor Larry Corey, who studies vaccines and infectious disease at Fred Hutch, a non-profit scientific research organization. "They optimize the assault of the human immune system on the complexity of the viral, bacterial, fungal and parasitic infections that live on our planet, to which we get exposed."
Despite their variety, coronaviruses share certain common proteins and other structural elements, Fuller explains, which the immune system can be trained to identify.
The current frontrunner vaccines aim to train our body to generate a sufficient amount of antibodies to neutralize the virus by shutting off its spike proteins before it enters our cells and begins to replicate. But a truly robust vaccine should also engender a strong response from T-cells, Fuller believes.
"Everyone focuses on the antibodies which block the virus, but it's not always 100 percent effective," she explains. "For example, if there are not enough titers or the antibody starts to wane, and the virus does get into the cells, the cells will become infected. At that point, the body needs to mount a robust T-cytotoxic response. The T-cells should find and recognize cells infected with the virus and eliminate these cells, and the virus with them."
Some of the frontrunner vaccine makers including Moderna, AstraZeneca and CanSino reported that they observed T-cell responses in their trials. Another company, BioNTech, based in Germany, also reported that their vaccine produced T-cell responses.
Fuller and her team are working on their own version of a coronavirus vaccine. In their recent study, the team managed to trigger a strong antibody and T-cell response in mice and primates. Moreover, the aging animals also produced a robust response, which would be important for the human elderly population.
But Fuller's team wants to engage T-cells further. She wants to try training T-cells to recognize not only SARV-CoV-2, but a range of different coronaviruses. Wild hosts, such as bats, carry many different types of coronaviruses, which may spill over onto humans, just like SARS, MERS and SARV-CoV-2 have. There are also four coronaviruses already endemic to humans. Cryptically named 229E, NL63, OC43, and HKU1, they were identified in the 1960s. And while they cause common colds and aren't considered particularly dangerous, the next coronavirus that jumps species may prove deadlier than the previous ones.
Despite their variety, coronaviruses share certain common proteins and other structural elements, Fuller explains, which the immune system can be trained to identify. "T-cells can recognize these shared sequences across multiple different types of coronaviruses," she explains, "so we have this vision for a universal coronavirus vaccine."
Paul Offit at Children's Hospitals in Philadelphia, who specializes in infectious diseases and vaccines, thinks it's a far shot at the moment. "I don't see that as something that is likely to happen, certainly not very soon," he says, adding that a universal flu vaccine has been tried for decades but is not available yet. We still don't know how the current frontrunner vaccines will perform. And until we know how efficient they are, wearing masks and keeping social distance are still important, he notes.
Corey says that while the universal coronavirus vaccine is not impossible, it is certainly not an easy feat. "It is a reasonably scientific hypothesis," he says, but one big challenge is that there are still many unknown coronaviruses so anticipating their structural elements is difficult. The structure of new viruses, particularly the recombinant ones that leap from wild hosts and carry bits and pieces of animal and human genetic material, can be hard to predict. "So whether you can make a vaccine that has universal T-cells to every coronavirus is also difficult to predict," Corey says. But, he adds, "I'm not being negative. I'm just saying that it's a formidable task."
Fuller is certainly up to the task and thinks it's worth the effort. "T-cells can cross-recognize different viruses within the same family," she says, so increasing their abilities to home in on a broader range of coronaviruses would help prevent future pandemics. "If that works, you're just going to take one [vaccine] and you'll have lifetime immunity," she says. "Not just against this coronavirus, but any future pandemic by a coronavirus."
On the morning of April 12, 1955, newsrooms across the United States inked headlines onto newsprint: the Salk Polio vaccine was "safe, effective, and potent." This was long-awaited news. Americans had limped through decades of fear, unaware of what caused polio or how to cure it, faced with the disease's terrifying, visible power to paralyze and kill, particularly children.
The announcement of the polio vaccine was celebrated with noisy jubilation: church bells rang, factory whistles sounded, people wept in the streets. Within weeks, mass inoculation began as the nation put its faith in a vaccine that would end polio.
Today, most of us are blissfully ignorant of child polio deaths, making it easier to believe that we have not personally benefited from the development of vaccines. According to Dr. Steven Pinker, cognitive psychologist and author of the bestselling book Enlightenment Now, we've become blasé to the gifts of science. "The default expectation is not that disease is part of life and science is a godsend, but that health is the default, and any disease is some outrage," he says.
The Rise and Fall of Public Trust<p>When the polio vaccine was released in 1955, "we were nearing an all-time high point in public trust," says Matt Baum, Harvard Kennedy School professor and lead author of <a href="http://www.kateto.net/covid19/COVID19%20CONSORTIUM%20REPORT%2013%20TRUST%20SEP%202020.pdf" target="_blank" rel="noopener noreferrer"><u>several</u></a> <a href="https://shorensteincenter.org/wp-content/uploads/2020/09/COVID19-CONSORTIUM-REPORT-14-MISINFO-SEP-2020.pdf" target="_blank" rel="noopener noreferrer"><u>reports</u></a> measuring public trust and vaccine confidence. Baum explains that the U.S. was experiencing a post-war boom following the Allied triumph in WWII, a popular Roosevelt presidency, and the rapid innovation that elevated the country to an international superpower.</p><p> The 1950s witnessed the emergence of nuclear technology, a space program, and unprecedented medical breakthroughs, adds Emily Brunson, Texas State University anthropologist and co-chair of the Working Group on Readying Populations for COVID-19 Vaccine. "Antibiotics were a game changer," she states. While before, people got sick with pneumonia for a month, suddenly they had access to pills that accelerated recovery. </p><p>During this period, science seemed to hold all the answers; people embraced the idea that we could "come to know the world with an absolute truth," Brunson explains. Doctors were portrayed as unquestioned gods, so Americans were primed to trust experts who told them the polio vaccine was safe. </p>
The Shift in How We Consume Information<p>In the 1950s, the media created an informational consensus. The fundamental ideas the public consumed about the state of the world were unified. "People argued about the best solutions, but didn't fundamentally disagree on the factual baseline," says Baum. Indeed, the messaging around the polio vaccine was centralized and consistent, led by President Roosevelt's successful <a href="https://files.eric.ed.gov/fulltext/EJ978264.pdf" target="_blank" rel="noopener noreferrer"><u>March of Dimes crusade</u></a>. People of lower socioeconomic status with limited access to this information were <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1551508/?page=3" target="_blank" rel="noopener noreferrer"><u>less likely to have confidence</u></a> in the vaccine, but most people consumed <a href="https://www.c-span.org/video/?506891-1/a-special-report-polio" target="_blank" rel="noopener noreferrer"><u>media that assured them</u></a> of the vaccine's safety and <a href="https://www.cbsnews.com/news/the-salk-polio-vaccine-greatest-public-health-experiment-in-history/" target="_blank" rel="noopener noreferrer"><u>mobilized them</u></a> to receive it. </p><p>Today, the information we consume is no longer centralized—in fact, just the opposite. "When you take that away, it's hard for people to know what to trust and what not to trust," Baum explains. We've witnessed an increase in polarization and the technology that makes it easier to give people what they want to hear, reinforcing the human tendencies to vilify the other side and reinforce our preexisting ideas. When information is engineered to further an agenda, each choice and risk calculation made while navigating the COVID-19 pandemic <a href="https://www.nytimes.com/2020/12/19/opinion/sunday/coronavirus-science.html?referringSource=articleShare" target="_blank" rel="noopener noreferrer"><u>is deeply politicized</u></a>. </p><p>This polarization maps onto a rise in socioeconomic inequality and economic uncertainty. These factors, associated with a sense of lost control, prime people to embrace misinformation, explains Baum, especially when the situation is difficult to comprehend. "The beauty of conspiratorial thinking is that it provides answers to all these questions," he says. Today's insidious fragmentation of news media accelerates the circulation of mis- and disinformation, reaching more people faster, regardless of veracity or motivation. In the case of vaccines, skepticism around their origin, safety, and motivation is intensified. </p><p>Alongside the rise in polarization, Pinker says "the emotional tone of the news has gone downward since the 1940s, and journalists consider it a professional responsibility to cover the negative." Relentless focus on everything that goes wrong further erodes public trust and paints a picture of the world getting worse. "Life saved is not a news story," says Pinker, but perhaps it should be, he continues. "If people were more aware of how much better life was generally, they might be more receptive to improvements that will continue to make life better. These improvements don't happen by themselves."</p>
The Future Depends on Vaccine Confidence<p>So far, the U.S. has been unable to mitigate the catastrophic effects of the pandemic through social distancing, testing, and contact tracing. President Trump has <a href="https://www.washingtonpost.com/politics/bob-woodward-rage-book-trump/2020/09/09/0368fe3c-efd2-11ea-b4bc-3a2098fc73d4_story.html" target="_blank" rel="noopener noreferrer"><u>downplayed the effects and threat of the virus</u></a>, <a href="https://www.washingtonpost.com/outlook/2020/07/14/cdc-directors-trump-politics/" target="_blank" rel="noopener noreferrer"><u>censored experts and scientists</u></a>, <a href="https://www.theatlantic.com/science/archive/2020/06/america-giving-up-on-pandemic/612796/" target="_blank" rel="noopener noreferrer"><u>given up on containing the spread</u></a>, and <a href="https://www.nytimes.com/2020/09/16/world/covid-coronavirus.html" target="_blank" rel="noopener noreferrer"><u>mobilized his base to protest masks</u></a>. The Trump Administration failed to devise a national plan, so our national plan has defaulted to hoping for the <a href="https://www.politico.com/news/2020/08/26/nation-of-miracles-pence-coronavirus-vaccine-rnc-402949" target="_blank" rel="noopener noreferrer"><u>"miracle" of a vaccine</u></a>. And they are "something of a miracle," Pinker says, describing vaccines as "the most benevolent invention in the history of our species." In record-breaking time, three vaccines have arrived. But their impact will be weakened unless we achieve mass vaccination. As Brunson notes, "The technology isn't the fix; it's people taking the technology."</p><p> Significant challenges remain, including facilitating widespread access and supporting on-the-ground efforts to allay concerns and build trust with <a href="https://www.newyorker.com/news/daily-comment/african-american-resistance-to-the-covid-19-vaccine-reflects-a-broader-problem" target="_blank" rel="noopener noreferrer"><u>specific populations with historic reasons for distrust</u></a>, says Brunson. Baum predicts continuing delays as well as deaths from other causes that will be linked to the vaccine. </p><p> Still, there's every reason for hope. The new administration "has its eyes wide open to these challenges. These are the kind of problems that are amenable to policy solutions if we have the will," Baum says. He forecasts widespread vaccination by late summer and a bounce back from the economic damage, a "Good News Story" that will bolster vaccine acceptance in the future. And Pinker reminds us that science, medicine, and public health have greatly extended our lives in the last few decades, a trend that can only continue if we're willing to roll up our sleeves. </p>
Imagine this scenario: you get an annoying cough and a bit of a fever. When you wake up the next morning you lose your sense of taste and smell. That sounds familiar, so you head to a doctor's office for a Covid test, which comes back positive.
Your next step? An anti-Covid nasal spray of course, a "trickster drug" that will clear the once-dangerous and deadly virus out of the body. The drug works by tricking the coronavirus with decoy receptors that appear to be just like those on the surface of our own cells. The virus latches onto the drug's molecules "thinking" it is breaking into human cells, but instead it flushes out of your system before it can cause any serious damage.
This may sounds like science fiction, but several research groups are already working on such trickster coronavirus drugs, with some candidates close to clinical trials and possibly even becoming available late this year. The teams began working on them when the pandemic arrived, and continued in lockdown.
Biochemist David Baker, pictured in his lab at the University of Washington.