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Skepticism abounds that a COVID-19 vaccine might be ready for wide-scale immunization in 12 to 18 months despite predictions from both scientific leaders and politicians in the Trump administration.

If "everything just worked amazingly well, I think it's conceivable that you could have pivotal data showing efficacy in 18 months,” said Karen Midthun, former director of the US Food and Drug Administration's Center for Biologics Evaluation and Research and current principal at regulatory consulting firm Greenleaf Health.  “I have a hard time imagining that you would actually have everything scale up and have a full approval by that time. Anything’s possible, but I think that would be a big stretch.”

Midthun said she would predict an approval could come 12 to 18 months from the start of Phase III studies. The COVID-19 vaccines furthest along are at the very beginning of Phase I studies.

Some vaccine experts express concern that the only way a vaccine could be available in a 12- to 18-month time frame would be if sacrifices were made on the quality of safety and efficacy data obtained.

"To just assume that 18 months from now we're all going to be having this magical vaccine that is safe and effective is not terribly realistic,” said Michael Kinch, Washington University in St. Louis, who worked on vaccine development at MedImmune. “I'm 100% a believer in vaccines, but they're not easy to develop. And to rush it, you're invariably going to have side effects that we didn't intend.”

Kinch also worried about creating “false expectations” for the public, who he said might be resentful and angry if there isn’t a vaccine in the promised time frame. “I think we just have to temper expectations.”

Paul Offit, a member of FDA’s Vaccines and Related Biological Products Advisory Committee and co-inventor of the rotavirus vaccine, said he couldn’t see how a COVID-19 vaccine could be held to the proper standards  for safety and efficacy and be in a position to be given to tens of millions of people within a year and a half.

Offit, who directs the vaccine education center at the Children’s Hospital of Philadelphia, said he believes a randomized placebo-controlled trial studying a hard outcome is likely needed in thousands if not tens of thousands of people because we do not know what the immunological correlate for coronavirus is – that is, how to assess whether the immune response a vaccine is evoking is protective based on the production of antibodies. A longer time frame for vaccine development is needed in the absence of an immunological correlate of protection. Studies will also be needed to determine how long a vaccine’s protection lasts.

For safety, he said at minimum enough people need to be tested “so you can feel comfortable that [if] they are exposed to the natural virus, that they don’t do worse” than if they had not received the vaccine. This is important, other vaccine experts said, because vaccines for other coronaviruses have ended up making infected patients sicker.

The need for pivotal trials that will assess a clinical outcome, not a surrogate, was emphasized by an array of vaccine experts, clinical researchers and bioethicists.

“There's a huge gap between production of antibodies and lowering the chances of very serious disease,” explained Peter Doshi a professor of pharmaceutical health services research at University of Maryland. “That's what we see with influenza vaccines year in and year out. [Flu vaccines] are approved well before you have evidence that it actually reduces chances of even having clinical influenza, let alone a serious complication. And the logic there is, you can't wait to approve it because then the season will be over. But they're approved because they are producing antibodies that they're aiming for. So by the laboratory values everything is a dream, right? And then we see the performance in the field and it's nothing like you would hope for.”

 

Midthun agreed that researchers should capitalize on the current environment where there is “rampant disease," to show whether a vaccine is effective in preventing disease.

Consider Immune Bridging, Head-To-Head Trials

The epidemiology will drive the study size and where the research takes place. Ideally trials will be done in areas where researchers understand the incidence rate of the virus, Midthun said. Researchers may be able to speed up the work by focusing on higher risk populations like health care workers and then potentially do “immune bridging to other populations,” she suggested.

“If you can show that other populations have a similar immune response than you could probably extrapolate efficacy from the [initial study] population,” Midthun said. A sponsor might be able to get the vaccine approved with a label for the smaller, high-risk population first and then could expand the indication once later studies completed.

Jesse Goodman, who served as FDA’s chief scientist from 2009 through 2014 and head of CBER for about a half dozen years before, said it will be important to include older people and people with underlying medical conditions early on in clinical trials, instead of focusing on the healthiest possible population. In a continuing outbreak, populations like these, which might often be left for post-marketing studies, should studied early, he said, as they are the ones that can get the most benefit from a vaccine. He suggested looking at people with higher risk of disease complications or people at high-risk for exposure like those in nursing homes as well.

Because there are multiple vaccine candidates, Goodman said it would be helpful if the various candidates could use similar study designs. This could allow for better comparison across products, even if they are not studied in head-to-head trials.

Norman Baylor, the former director of the FDA’s Office of Vaccine Research and Review, argued for studies that directly compare competing products. “Although manufacturers don’t readily embrace having their product [studied] head-to-head,” he was hopeful this could be a possibility given the amount of government funding going into COVID-19 work.

Manufacturing To Scale Will Be Added Hiccup 

Even if adequate pivotal studies and FDA review of a vaccine application could be completed in a year or a year and a half, getting a large amount of doses manufactured so they could be administered quickly following approval is unlikely, said Vijay Samant, who spent more than 20 years at Merck & Co., including in leadership roles on vaccine development, before leading Brickell Biotech from 2000 to 2019

There are four components to manufacturing validation, he said – assay validation, process validation, equipment validation and validation of your cleaning processes.

“If you ask any vaccine manufacturer… that validation activity alone can take you nine to 12 months to complete,” Samant said. After that you need to scale up the formulation process and make full doses.

Even with companies like Moderna and Johnson and Johnson promising to scale up manufacturing very early in clinical development, Samant was skeptical of the promises of a vaccine in a year to a year and a half
(Also see "J&J Ramps Up Manufacturing Capacity To Produce 1 Billion Doses Of Candidate COVID-19 Vaccine" - Pink Sheet, 30 Mar, 2020.).

“This is a massive undertaking,” he said.

 

 

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