SARS-CoV-2 (shown here in an electron microscope picture). Credit: National Institute for Allergy and Infectious Diseases, NIH

Vaccines are hailed as a solution to the COVID-19 pandemic, but the vaccine trials currently underway are not meant to tell us whether they will save lives, reports Peter Doshi, Associate Editor at The BMJ today.

Several COVID-19 vaccine trials are currently in their most advanced stage (Phase 3). But what exactly does this mean when a vaccine is declared “effective”?

Many can assume that successful phase 3 studies mean that there is evidence that we can prevent people from getting very sick and dying from COVID-19. And a robust way to interrupt virus transmission.

However, the current phase 3 studies are not meant to prove either, says Doshi.

“None of the ongoing studies are expected to see a reduction in major outcomes such as hospital stays, critical care, or deaths. The vaccines are also not being tested to see if they can interrupt transmission of the virus,” he writes.

He explains that all ongoing Phase 3 studies, for which details have been released, are evaluating mild, non-serious illnesses – and they will be able to report final results once around 150 participants develop symptoms.

For example, in the Pfizer and Moderna studies, people with just one cough and a positive lab test would bring these studies one event closer to completion.

However, Doshi argues that vaccine manufacturers have done little to dispel the notion that serious COVID-19 has been investigated.

Moderna, for example, described hospital stays as an “important secondary endpoint” in statements to the media. Tal Zaks, Chief Medical Officer at Moderna, told the BMJ that their study did not have sufficient statistical power to assess this endpoint.

Part of the reason could be numbers, Doshi says. Because most people with symptomatic COVID-19 infections have mild symptoms, even studies of 30,000 or more patients would show relatively few cases of serious illness.

“Hospitalizations and deaths from COVID-19 are simply too rare in the studied population to get an effective vaccine to show statistically significant differences in a study of 30,000 people,” he adds. “The same applies to the question of whether it can save lives or prevent transmission: the experiments are not designed to find out.”

Zaks confirms that Moderna’s study will not demonstrate any prevention of hospitalization as the size and duration of the study would have to be increased significantly to collect the required data. “In my opinion, both are acceptable in the current public need to know quickly that a vaccine is working,” he told the BMJ.

Moderna’s study is set to find out if the vaccine can prevent COVID-19 disease, Zaks says. Like Pfizer, Johnson, and Johnson, Moderna designed its study to find a relative risk reduction of at least 30% in subjects who develop laboratory-confirmed COVID-19. This is in line with the FDA and international guidelines.

Zaks also points out influenza vaccines, saying they protect better against serious illnesses than against minor illnesses. “For Moderna, it’s the same with COVID-19: if their vaccine is shown to reduce the symptomatic COVID-19, they are confident that it will also protect against serious consequences,” Doshi writes.

Doshi raises another important problem, however: Few, or perhaps none of the current vaccine studies appear to be designed to find out whether the elderly, despite their apparent susceptibility to COVID-19, are of benefit.

If frail elderly people do not participate in vaccination trials in sufficient numbers to see if there is a reduction in cases in this population, “there can be little basis on which to suggest any benefit against hospitalizations or mortality,” he warns.

Doshi says we still have time to campaign for changes to ensure that ongoing studies answer the questions that need most urgent answers.

For example, why children, immunocompromised people and pregnant women have been largely excluded; whether the correct primary endpoint has been selected; whether the security is adequately assessed; and whether it will fill gaps in our understanding of how our immune systems react to COVID-19.

“The COVID-19 vaccine trials may not have been developed with our input, but it is not too late to have a say and adjust their course. At such high stakes, we all need eyes on deck,” he argues.

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More information:
Will Covid-19 Vaccines Save Lives? Current studies are not supposed to tell us BMJ (2020). DOI: 10.1136 / bmj.m4037 Provided by the British Medical Journal

Quote: COVID-19 vaccine studies cannot tell us if they will save lives (2020, October 21), accessed October 22, 2020 from https://medicalxpress.com/news/2020-10-covid-vaccine-trials .html

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