On coronavirus vaccine, don't hold your breath, experts say

The announcement on May 18 that a candidate vaccine for the coronavirus appeared to create an immune response in a handful of people sent spirits, and the stock market, soaring. President Trump has raised the tantalizing possibility that the COVID-19 pandemic could be ended by a vaccine as soon as the start of next year.

But infectious disease specialists and vaccine developers interviewed by Yahoo News said that even accepting the unpublished research at face value, it is unclear if or when an effective vaccine will be available. This uncertainty raises questions about whether the extreme social distancing measures in place in many parts of the country will continue indefinitely.

“All the enthusiasm results from one trial with 8 people in it,” said George Rutherford, a professor of epidemiology at the University of California at San Francisco. “Like 1, 2, 3, 4, 5, 6, 7, 8. So it’s quite preliminary.”

Asked why so many people have reacted to the news out of the Moderna trial with such enthusiasm, Rutherford said, “People are talking themselves into it.”

George Rutherford
Dr. George Rutherford, professor of epidemiology at the UC Berkeley School of Public Health (University of California, Berkeley)

Rutherford added that he has been buoyed by how relatively positive the government’s top infectious disease specialist Dr. Anthony Fauci has been regarding the prospects for a vaccine in the next 12 to 18 months, but he said that the timetable for manufacturing and distributing a vaccine could be far longer than estimates thus far have allowed for.

“If he’s optimistic, I’m optimistic, but the logistics of manufacturing it — manufacturing 330 million doses — if we only need one dose — and the logistics of administering it still remain big lifts,” said Rutherford, who noted that in the 1960s, Nigerian officials had to fill entire soccer stadiums for days in a campaign for mass vaccination against smallpox.

Rutherford said that if a vaccine is created, it could offer only “partial protection,” meaning that multiple shots are required to confer full immunity on those with suppressed immune systems or an annual shot even for those without underlying conditions or on medications that cause immune suppression.

“Having to get re-immunized every year like we do influenza, or having some complicated initial course with two to three different types of vaccines that are given at a certain interval — the logistics of getting that done would be horrific,” Rutherford said.

Along with several other experts, Rutherford said that while he hopes a vaccine is available by the middle of next year, there are no guarantees. He said that he has more hope for a vaccine in the next year or two because this coronavirus appears not to mutate significantly and, unlike HIV, for which there is still no approved vaccine despite decades of research, it does not attack a key cell in the immune system.

Dr. Francis Collins, director of the National Institutes of Health, told Yahoo News in an interview that vaccines are never 100 percent effective. Collins said the measles shot — one of society’s most successful vaccines — is 98 percent effective, whereas the flu vaccine is only 30 percent effective some years.

Francis Collins
Dr. Francis Collins, director of the National Institutes of Health. (Anna Moneymaker/New York Times/Bloomberg via Getty Images)

“It all depends on the details, and it particularly depends on how it works for the most susceptible individuals,” Collins told Yahoo News in an interview. “They’re the ones we most want to protect. If you had something that provided significant benefit — even if it wasn’t 100 percent successful — for the most vulnerable people, you’d probably want to offer it to them while still trying to get something even better.”

Ian Haydon, who participated in the Moderna trial, is a possible example of what Collins is talking about: Vaccine dosing can be tricky. Haydon received a high dose of the Moderna candidate vaccine and developed a 103-degree fever and fainted in his home even after receiving medical care. He has since fully recovered.

“Part of this trial involves finding the right dose — one that is effective but doesn’t make people sick,” Haydon told Yahoo News in an email interview. “The high dose might be too high. Moderna, the company behind this vaccine, won’t be testing the high dose in future trials.”

David Walt, a professor of pathology at Brigham and Women’s Hospital at Harvard Medical School, runs the lab which he said created the “gold standard” antibody test now in use. Walt said he has been encouraged by recent data showing monkeys that developed an immune response after inoculation. He has also been cheered by what he called “developing evidence that at least those individuals who develop robust immune responses to the virus seem to be protected from infection” a second time.

But Walt emphasized how little we still know about this coronavirus. “There is a range of responses to the virus — individuals who have recovered exhibit varying levels of antibodies and those are characterized by both the types of antibodies that they develop as well as the amount of antibodies, the concentration of antibodies,” Walt said. “Some individuals do not develop a particularly robust response to viral infection, so how long or how well they are protected relative to individuals who have developed strong responses remains to be seen.”

David Walt
Dr. David Walt. (Wyss Institute at Harvard University)

Walt said this question will influence development of the vaccine since “we’re in the very early stages of this disease” and therefore don’t know how robust or how long-lasting that response is going to be. He said that with other coronaviruses such as SARS and MERS, antibody protection wanes over time.

“Even if the vaccine were to produce an effective protection, it may be that we need to be revaccinated every year or every two years — it’s just unknown how long the response to the vaccine is going to last,” Walt said.

As with others interviewed by Yahoo News, Walt cautioned against assuming a safe vaccine will arrive in the next year.

“Just because we’re seeing some early promising results with small numbers of individuals developing these immune responses that seem to recapitulate the infection, it still is a long way to get to the confidence that we need that any one of these vaccines is going to be safe,” Walt said. “Just because it’s effective does not necessarily mean it’s going to be safe when you start to scale this to thousands, tens of thousands and then millions of people.”

Walt pointed to problems with the polio vaccine as an example of the challenges vaccine developers now confront.

“It was tested in a large number of people over a long period of time — years — and then once it was scaled [up], some kids exhibited symptoms of polio because the virus was not completely inactivated,” Walt said. “They were rare events but nonetheless pretty dramatic and not what we want to have if something like this scaled and caused lots of adverse effects.”

Walt agreed that it is important for people to understand that developing a safe and effective vaccine will be what Rutherford called “a moonshot effort.” Every pharmaceutical company is looking for one, but safe and effective vaccines take time.

Paul Offit, one of the inventors of a vaccine against rotavirus, which causes often-fatal diarrhea in young children, said he believes it is reasonable to hope the coronavirus vaccine provides protection against moderate to severe disease, but that it may well not protect against asymptomatic reinfection or mild symptoms associated with infection.

“This is a stable virus,” Offit said. “So this is not flu and although it’s true that you may have protection only for a few years and not for decades, you should have protection I would think for a few years.

Offit said it helps that the large body of work already done on coronaviruses is available to researchers because it allows them to better predict how the COVID-19 vaccine might work. He said that studies done years ago with human coronavirus suggest that a vaccine will offer protection since most people were still protected a year after vaccination.

You know the virus doesn’t mutate significantly, you know the protein you are interested in — you’re interested in that spike protein — [and] if you can make antibodies to the spike protein you’re going to prevent the virus from binding to cells and prevent it from infecting you,” Offit said. “I think there will be a successful vaccine. It may not provide what is referred to among virologists as ‘sterilizing immunity,’ meaning protection against even asymptomatic disease associated with exposure. But that’s OK.”

Mark Milley
Chairman of the Joint Chiefs of Staff Gen. Mark Milley. (Mandel Ngan/AFP via Getty Images)

Although last week Army Gen. Mark Milley, chairman of the Joint Chiefs of Staff, promised a vaccine would be developed by this fall, Offit said he considers the middle of next year a more realistic date.

Offit, who said he is part of the NIH “active group” determining a timetable for a vaccine, said that next month an NIH study will begin for each vaccine and that each candidate vaccine will involve 20,000 people getting a protective dose and 10,000 receiving a placebo.

“You have to recruit those people — you have to recruit them in areas hopefully where there’s outbreaks or ongoing infections so that you can capture enough people in the placebo group so you can say the vaccine is effective,” he said. “I just don’t see that happening in the fall.”

Offitt, a professor of pediatrics at the Children’s Hospital of Philadelphia, worked for 25 years on the rotavirus vaccine. He told CNN in April that he believed Fauci’s 12-to-18-month time line was “ridiculously optimistic.” While his views have evolved in a more positive direction, he warned that the virus has been hard to predict.

“This has been a surprising virus in a number of ways and we should be humble that we don’t know all the answers,” he said.

Dr. Donald Forthal, chief of the infectious diseases division at the University of California at Irvine, has long studied HIV and dengue fever antibody response, and more recently has focused on the coronavirus. He said that while a vaccine is far from guaranteed and a safe and effective vaccine will take time, it will likely offer enough herd immunity for social distancing guidelines to be relaxed.

“Even if there’s a portion of people that aren’t protected either fully or at all, such a vaccine would be very helpful, and I think things could largely go back to normal,” he said. And he said he is hopeful that other treatments will materialize for the illness.

“It’s nice to have alternatives [to] vaccination,” Forthal said. “If your immune system is depressed, you may not respond sufficiently to a vaccine.”

Forthal said people need to prepare for a longer time frame for a vaccine than what has been promised by the president, who he said is “likely setting us up for disappointment.” Even once approved, a vaccine is not a cure all.

“Even the best vaccine is likely to have holes in its coverage, and I’ve not seen people discussing that,” Forthal said. “I don’t want to be pessimistic, but i just think we need to be prepared to protect people who may not benefit for one reason or another from a vaccine.”

Thumbnail cover photo: Getty Images


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