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Friday, March 5th, 2021

COVID-19 vaccine efficacy should be based on standardized methods, Oxford scientists say

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A collaborative paper from researchers at the University of Oxford, published in The Lancet Infectious Diseases journal this week, argued that meaningful comparison between potential COVID-19 vaccines will need standardized methods and ongoing studies to determine efficacy.

The authors of the opinion piece included Drs. Susanne Hodgson and Kate Emary, both of the University of Oxford. Therein, they argued that these measures are critical to ensuring the most effective candidates reach the market. Even after licensing and deployment, they said that ongoing studies would be necessary to determine if these vaccines could prevent severe disease or death from COVID-19, as clinical trials may not be able to achieve this.

They also warned that controlled human infection studies — or challenge trials — might allow for rapid assessment of efficacy, but remain unclear if they can predict that efficacy for all or just the young.

“It is unlikely that we will see a single vaccine winner in the race against COVID-19,” Hodgson said. “Different technologies will bring distinct advantages that are relevant in different situations, and additionally, there will probably be challenges with manufacturing and supplying a single vaccine at the scale required, at least initially. Taking a standardised approach to measuring the success of vaccines in clinical trials will be important for making meaningful comparisons so that the most effective candidates can be taken forward for wider use.”

There are currently 44 candidates in clinical assessment and another 154 potentials in preclinical development. Without standardized assessment methods, though, Hodgson and her colleagues fear that these vaccines’ limitations and potential for bias might be missed. With all the focus on the rush — such as the U.S.-based Operation Warp Speed — people also risk vaccine safety.

“To determine whether a vaccine protects against severe COVID-19 disease, a clinical trial needs to show that there are significantly fewer cases of severe disease in individuals vaccinated with a COVID-19 vaccine, compared with individuals who were not,” Emary said. “However, only a small proportion of individuals infected with SARS-CoV-2 develop severe disease, which means an extremely large number of volunteers is needed in a clinical trial for there to be enough cases to get a reliable measure of vaccine efficacy. This means that it is likely that we will only know if a vaccine protects against severe disease once it has been deployed and given to a large population.”

Both doctors agreed that vaccine development should be focused on gaining evidence of vaccine efficiency so the manufacture of vaccines could be selectively upscaled — not pushed forward on safety and immunogenicity data alone.