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What are clinical trials and how do they work?

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Ivan Couronne, Agence France-Presse

<div class="embed-wrap"><figure data-feedback="fb:likes,fb:comments"><img src="https://sa.kapamilya.com/absnews/abscbnnews/media/2020/reuters/11/17/lab.jpg"/><figcaption>A researcher works in a lab run by Moderna Inc, who said November 16, 2020 that its experimental vaccine was 94.5% effective in preventing COVID-19 based on interim data from a late-stage clinical trial, in an undated still image from video.<em> Moderna Inc/Handout via Reuters</em></figcaption></figure></div><p>WASHINGTON - To find out whether experimental COVID-19 vaccines are safe and effective, researchers design clinical trials involving thousands of volunteers, divided into groups that receive either the drug under investigation or a placebo. </p><p>Data from such trials have shown that two vaccines -- one developed by Pfizer and BioNtech, the other by Moderna and the US National Institutes of Health -- are about 95 percent effective.</p><ul class="op-related-articles">	<li><a href="https://news.abs-cbn.com/news/11/18/20/pfizer-ends-covid-19-trial-with-95-efficacy-to-seek-emergency-use-authorization">Pfizer ends COVID-19 trial with 95% efficacy, to seek emergency-use authorization</a></li>	<li><a href="https://news.abs-cbn.com/overseas/11/16/20/moderna-says-its-vaccine-is-945-effective-in-preventing-COVID-19">Moderna says its vaccine is 94.5% effective in preventing COVID-19</a></li></ul><p>Here&#x27;s a look at how trials work:</p><div><strong>WHO LEADS CLINICAL TRIALS?</strong></div><p>American pharmaceutical Pfizer itself has led and financed a clinical trial of its vaccine involving almost 44,000 people in the United States, Germany, Turkey, South Africa, Brazil and Argentina.</p><p>Volunteers who are accepted receive two doses 21 days apart and get regular follow-up.</p><p>The Moderna-NIH vaccine is given 28-days-apart at locations across the US on some 30,000 volunteers, in a trial part funded by the taxpayer.</p><p>The trials are &quot;blinded&quot; meaning neither the volunteers nor the health care providers know who gets the medicine and who gets a saline solution placebo.</p><div><strong>HOW DO WE KNOW IF THE VACCINES WORKED?</strong></div><p>Volunteers have not been deliberately infected with the virus. This option, known as a challenge trial, was considered but deemed too risky given that there aren&#x27;t any COVID-19 treatments that are proven as highly-effective.</p><p>Instead volunteers are expected to go about their lives as normal, and are given the same advice about mask use, distancing and hand washing as everyone else.</p><p>Over the course of time, a certain number naturally become infected, and since they&#x27;re getting regular follow-up, the trial investigators quickly find out.</p><p>If the vaccine is effective, the number of people who fall sick in the vaccine group should be lower than the number of people who get ill in the placebo group.</p><p>The aim is to find a difference great enough to exclude the possibility it occurred by chance. Statistical methods come into play to achieve a predetermined level of certainty. </p><p>It&#x27;s worth noting that the primary goal is to prevent people from getting sick, with good vaccines also protecting people from severe illness.</p><p>Stopping people from getting infected at all, and thus being able to transmit the virus forward, is a secondary goal for Moderna.</p><p>Moncef Slaoui, chief of the US government&#x27;s Operation Warp Speed, said Wednesday he expects the vaccines will achieve these goals too, though at a lower efficacy rate.</p><div><strong>WHY HAVE A PLACEBO?</strong></div><p>The only way of knowing whether a vaccine works is by providing a &quot;control&quot;, which is a demonstration of what would happen in its absence. </p><p>Of course, different people have different risk profiles in terms of their ages, underlying conditions, and how much risky behavior they engage in. </p><p>That&#x27;s why the trials need to be scaled to tens of thousands of people to eliminate confounding factors.</p><div><strong>WHO ANALYZES THE DATA?</strong></div><p>To ensure scientific rigor is upheld, the data is firewalled from the companies and analyzed by experts in a &quot;data and safety monitoring board&quot; whose membership is kept secret to prevent political pressure.</p><p>Over the course of a trial, these committees will lift the hood on the data that&#x27;s been collected so far and see which patients belonged to which group.</p><p>They can then inform the manufacturer in case of conclusive results and the manufacturer can then use the data, if it&#x27;s favorable, to apply for a marketing authorization. </p><p>The boards also closely monitor safety, looking at the frequency and severity of side-effects, a key factor in determining regulatory approval.</p><div><strong>95 PERCENT EFFICACY?</strong></div><p>Pfizer&#x27;s efficacy analysis featured 170 people who fell sick with COVID-19 in the seven days following the second dose, which might seem like a small number of people compared to the total trial participants (44,000).</p><p>But it&#x27;s enough to say the result is statistically significant with a high-degree of certainty. </p><p>That&#x27;s because 162 people who fell ill were on the placebo, and only eight were in the vaccine group -- a difference so great it&#x27;s extremely improbable to come about by chance.</p><p>An efficacy of 95 percent signifies that the risk of catching COVID-19 is reduced by 95 percent in the vaccinated group compared to the placebo group.</p><div><strong>PLACEBO GROUP GET VACCINE?</strong></div><p>They will all be transferred to the vaccine arm -- but it is still being decided when that will happen, said Slaoui. </p><p>The Pfizer and Moderna trials will therefore lose their &quot;control&quot; groups, but the participants will still be followed for two more years to determine how long immunity lasts and whether there are longer-term safety effects.</p><p>It will also make it harder to recruit new people to ongoing trials for vaccines that aren&#x27;t yet as close to applying for approval.</p><figure class="op-interactive"><iframe height="315" src="https://www.youtube.com/embed/I_9-rzpFMdk?enablejsapi=1" width="560"></iframe></figure><div class="iwantbar">Watch more in <a href="//www.iwantv.com.ph/">iWantv</a> or <a href="//tfc.tv/">TFC.tv</a></div>

<p>To find out whether experimental COVID-19 vaccines are safe and effective, researchers design clinical trials involving thousands of volunteers, divided into groups that receive either the drug under investigation or a placebo. </p>

To find out whether experimental COVID-19 vaccines are safe and effective, researchers design clinical trials involving thousands of volunteers, divided into groups that receive either the drug under investigation or a placebo.

What are clinical trials and how do they work?

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What are clinical trials and how do they work?

Ivan Couronne,

Agence France-Presse

Published Nov 19, 2020 10:56 AM PHT

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Updated Nov 19, 2020 11:23 AM PHT

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COVID-19 vaccine

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