Covid-19 vaccine candidate is 90% effective, says manufacturer

I&#x27;m not sure to understand what 90% means in this context.<p>We know that more than 80% of the infected people do not show any symptoms, and that around 0.5% (mostly elders) die from COVID.<p>Do the 90% addresses the death rate of those 0.5% ?

But also:<p><a href="https:&#x2F;&#x2F;www.fiercepharma.com&#x2F;manufacturing&#x2F;pfizer-biontech-near-euro-supply-deal-for-up-to-300m-doses-covid-19-vaccine" rel="nofollow">https:&#x2F;&#x2F;www.fiercepharma.com&#x2F;manufacturing&#x2F;pfizer-biontech-n...</a><p>&quot;Analysts specifically cast doubt on Pfizer and BioNTech&#x27;s rollout plans given the stringent cold-storage needs for their candidate, which must be kept at a frigid -94° Fahrenheit (-70° Celsius), and will last for only 24 hours at refrigerated temps between 35.6°F and 46.4°F (2°-8°C).<p>By contrast, most protein subunit vaccines—the type being developed for COVID-19 by Sanofi and Novavax, among others—can be held at refrigerated temps for months, analysts said.&quot;

Just after election result!