Scientific Doubt Tempers COVID-19 Vaccine Optimism

Marcia Frellick

May 28, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

US government and industry projections that a COVID-19 vaccine will be ready by this fall or even January would take compressing what usually takes at least a decade into months, with little room for error or safety surprises.

"If all the cards fall into the right place and all the stars are aligned, you definitely could get a vaccine by December or January," Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, said last week.

But Fauci said a more realistic timeline is still 12 to 18 months, and experts interviewed by Medscape Medical News agree. They say that although recent developments are encouraging, history and scientific reason say the day when a COVID-19 vaccine is widely available will not come this year and may not come by the end of 2021.

The encouraging signals come primarily from two recent announcements:

the $1.2 billion United States backing last week of one vaccine platform and the announcement on May 18 that the first human trials of another have produced some positive phase 1 results.

Recent Developments

On May 21, the US Department of Health and Human Services (HHS) under "Operation Warp Speed" announced that the US will give AstraZeneca $1.2 billion "to make available at least 300 million doses of a coronavirus vaccine called AZD1222, with the first doses delivered as early as October 2020."

On May 18, the Massachusetts-based biotechnology company Moderna announced that phase 1 clinical results showed that its vaccine candidate, which uses a new messenger RNA (mRNA) technology, appeared safe. Eight participants in the human trials were able to produce neutralizing antibodies that researchers believe are important in developing protection from the virus.

Moderna Chief Medical Officer Tal Zaks, MD, PhD told CNN that if the vaccine candidate does well in phase 2, "it could be ready by January 2021."

The two candidates are among 10 in clinical trials for the SARS-CoV-2 virus, according to the World Health Organization (WHO). The AstraZeneca/ AZD1222 candidate (also called ChAdOx1 nCoV-19, in collaboration with the University of Oxford) has entered phase 2/3.

Moderna's candidate and another being developed in Beijing, China, are in phase 2, WHO reports. As of yesterday, 115 other candidates are in preclinical evaluation.

Maria Elena Bottazzi, PhD, associate dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston, Texas, told Medscape Medical News it's important to realize that, in the case of the $1.2 billion US investment, "what they're talking about is manufacturing."

The idea, she said, is to pay AstraZeneca up front so that manufacturing can start before it is known whether the vaccine candidate is safe or effective, the reverse of how the clinical trial process usually works.

That way, if the candidate is deemed safe and effective, time is not lost by then deciding how to make it and distribute it.

By the end of this year, she said, "Maybe we will have many vaccines made and stored in a refrigerator somewhere. But between now and December, there's absolutely no way you can show efficacy of the vaccine at the same time you confirm that it's safe."

"Take These Things With a Grain of Salt"

Animal testing for the AstraZeneca candidate, made in partnership with the University of Oxford in the United Kingdom, has yielded lackluster results, according to results on the preprint server BioRxiv, which have not been peer-reviewed.

"The results were not bad, but they were not gangbusters," Bottazzi said. The results show the vaccine offered only partial protection.

"Partial protection is better than no protection," she noted. "You have to take these things with a grain of salt. We don't know what's going to happen in humans."

As for the Moderna candidate, Bottazzi said, "the good news is they found an appropriate safety profile. But from an eight-person group to make the extrapolation that they have efficacy — it's unrealistic."

Nicole Lurie, MD, MSPH, is senior adviser to the CEO for the Coalition for Epidemic Preparedness Innovation (CEPI), a nongovernmental organization funded by the Wellcome Trust, the Bill and Melinda Gates Foundation, the European Commission, and eight countries (Australia, Belgium, Canada, Ethiopia, Germany, Japan, Norway, and the United Kingdom) charged with supporting development of vaccines for pathogens on WHO's priority list.

She and her colleagues write in a paper published online in the New England Journal of Medicine on March 30 that "it typically takes multiple candidates and many years to produce a licensed vaccine."

The fastest time for developing a vaccine to date is 4 years, for the mumps vaccine, licensed in 1967.

As to whether she would expect a rollout of any vaccine by the end of the year, Lurie told Medscape Medical News, "If everything goes according to plan in every way, shape or form, well then maybe you can get there. But I wouldn't hold my breath."

Lurie and her colleagues write that "it's far from certain that these new platforms will be scalable or that existing capacity can provide sufficient quantities of vaccine fast enough."

On a call with reporters today, leaders of some of the words largest pharmaceutical companies said that one of the key bottlenecks is the sheer number of vials needed in order to distribute billions of doses of a successful vaccine.

Pfizer CEO Albert Bourla, DVM, PhD, said, "Typically we are producing vaccines in single-dose vials. We are exploring with governments right now if it would be more convenient if there were 5-dose vials or 10-dose vials. I think we can resolve a significant part of the bottleneck."

Despite the challenges, experts interviewed for this article agree that it will be possible to make a vaccine for COVID-19. They don't expect attempts to meet the same complications that HIV researchers have seen over decades as the virus continues to confound with mutations.

Fred Ledley, MD, director of the Center for Integration of Science and Industry at Bentley University in Waltham, Massachusetts, told Medscape Medical News, "There doesn't appear to be anything terribly diabolical about this virus. The mutation rate doesn't appear to be anything like HIV. It appears to have some big, ugly proteins on the surface, which is good for vaccines — proteins with a lot of physical features look distinguishable from healthy cells. Signs all point to that it should be possible to make a vaccine."

History Raises Safety Concerns

However, Ledley said, "The idea of doing it in 6 months is largely unrealistic."

He says 18 months is more realistic, primarily because of the sheer number of people that would have to be enrolled in a phase 3 study to truly test whether the endpoints are being met.

Vaccines are given to healthy volunteers. If safety signals arise, they may not be apparent until massive numbers of people are tested in phase 3.

"You're never going to see the rates cut to 0%, but to see the difference between 10 people getting sick and seven people getting sick, takes very, very large numbers," Ledley said. "There's no way that can be done in 6 months. You're talking about tens of thousands of people enrolled."

He notes at this point it's unclear what the endpoints will be and what the safety thresholds will be after consideration of risks and benefit.

Another big question for Ledley: "We don't know what type of immunity we need to protect us against the virus. Do you just need the antibodies in your blood or do you need cells that are primed to attack the virus? Is it more of a chemical clearance or do the cells need to physically go in and digest the virus?"

History also points to the need for rigorous safety precautions that scientists fear could be compromised as trial phases overlap and processes are run in parallel instead of one step at a time.

An early batch of the Salk vaccine for polio in 1955, for example, turned out to be contaminated and caused paralysis in some children and 10 deaths, he points out.

CEPI's Lurie adds that early candidates for another coronavirus, severe acute respiratory syndrome (SARS), "caused a reaction in the lungs that was very dangerous" before development was halted.

She also pointed to previous findings that a vaccine for dengue fever could worsen the disease in some people through a phenomenon called antibody-dependent enhancement.

Lurie and colleagues write in their paper that "it's critical that vaccines also be developed using the tried-and-true methods, even if they may take longer to enter clinical trials or to result in large numbers of doses."

Live Attenuated Vaccine

Raul Andino, PhD, a virologist at the University of California San Francisco, is among the scientists working with a tried-and-true method ­— a live attenuated vaccine — and he told Medscape Medical News he's predicting it will take 2 years to develop.

He said it is cheaper to produce because scientists just have to learn how to grow the virus. Because the technology is already proven, a live attenuated vaccine could be rapidly produced on a worldwide scale.

The hope is also that a live attenuated vaccine would be given once in a lifetime and therefore be more affordable, especially in poorer countries.

"While a Moderna vaccine might be good for Europe and the United States," he said, "It's not going to be good for Africa, India, Brazil."

Andino said, "I would bet money" that the front-runner vaccines so far will not be one-time vaccines.

He points out that most of the vaccine candidates are trying to protect people from disease. While there's nothing wrong with that, he said, "In my opinion that is the lower-hanging fruit."

"In my mind we need something that interrupts the chain of transmission and induces protection," Andino said, important for developing herd immunity.

The reason this type of approach takes longer is because you are introducing a weakened form of the virus to the body and you have to make sure it doesn't cause disease, not just in a small test population, but in populations who may be more susceptible to the disease, Andino said.

A Call for Unified Strategies

Universities, countries, international consortiums, and public-private partnerships are all racing to find several safe and effective vaccines as no one entity will likely be able to provide the global solution.

Some of the efforts involve overlap of entities but with different focuses.

Along with "Operation Warp Speed" and CEPI, other collaborations include Gavi the Vaccine Alliance, whose core partners include WHO, UNICEF, the World Bank, and the Gates Foundation; and "Accelerating Therapeutic Interventions and Vaccines (ACTIV) partnership," led by the National Institutes of Health.

Industry partners in ACTIV (18 biopharmaceutical companies), according to a May 18 article published online in the Journal of the American Medical Association, have said they will contribute their respective clinical trial capacities, regardless of which agent is studied.

Some, however, have called for more streamlining of efforts.

"Ideally we'd be working together," Lurie told Medscape Medical News.

"I'm hopeful we will find ways to collaborate scientifically," she said. "The US government's responsibility is to make doses for the US. CEPI's responsibility is to make doses for the world. A big focus of CEPI is to make sure we have manufacturing capacity outside of the US so those doses can be available to the world and they don't get seized by wealthy countries."

Marcia Frellick is a freelance journalist based in Chicago. She has previously written for the Chicago Tribune and and was an editor at the Chicago Sun-Times, the Cincinnati Enquirer, and the St. Cloud (Minnesota) Times. Follow her on Twitter at @mfrellick

Bottazzi, Ledley, Lurie, and Andino report no relevant financial relationships.

Bottazzi and her research partner, Peter Hotez, MD, are working to develop COVID-19 vaccines through the National School of Tropical Medicine at Baylor and the Center for Vaccine Development at Texas Children's.


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