Dödligt virus från Kina orsakar panik (SARS-CoV-2, COVID-19)

All COVID-19 vaccines*approved*by WHO for*emergency use listing*have been through randomized clinical trials to test their quality, safety and efficacy. To be approved, vaccines are required to have a high efficacy rate of 50% or above. After approval, they continue to be*monitored*for ongoing safety and effectiveness. But what is the difference between efficacy and effectiveness?

A vaccine’s*efficacy*is measured in a controlled clinical trial and is based on how many people who got vaccinated developed the ‘outcome of interest’ (usually disease) compared with how many people who got the placebo (dummy vaccine) developed the same outcome. Once the study is complete, the numbers of sick people in each group are compared, in order to calculate the relative risk of getting sick depending on whether or not the subjects received the vaccine. From this we get the efficacy – a measure of how much the vaccine lowered the risk of getting sick. If a vaccine has high efficacy, a lot fewer people in the group who received the vaccine got sick than the people in the group who received the placebo.

So, for example, let’s imagine a vaccine with a proven efficacy of 80%. This means that – out of the people in the clinical trial – those who received the vaccine were at a 80% lower risk of developing disease* than the group who received the placebo. This is calculated by comparing the number of cases of disease in the vaccinated group versus the placebo group. An efficacy of 80% does*not*mean that 20% of the vaccinated group will become ill.*

Vaccine*effectiveness*is a measure of how well vaccines work in the real world. Clinical trials include a wide range of people – a broad age range, both sexes, different ethnicities and those with known medical conditions – but they cannot be a perfect representation of the whole population. The efficacy seen in clinical trials applies to specific outcomes in a clinical trial . Effectiveness is measured by observing how well the vaccines work to protect communities as a whole. Effectiveness in the real world can differ from the efficacy measured in a trial, because we can’t predict exactly how effective vaccination will be for a much bigger and more variable population getting vaccinated in more real life conditions.

Man godkänner inte ett vaccin med ”provisorisk” information. Det tror jag till och med du kan förstå om du tänker till lite grann.

Och om du fortfarande tror det, så har du accepterat att du nu ingår i ett medicinskt experiment, där vi nu väntar på bättre, icke provisorisk, information.