How do they know that the Covid Vaccine is efficacious?

Tista' taqra bil- Malti.

As the Covid pandemic rages unabated, the world awaits, with bated breath, for the vaccine to be rolled out. This expectation is no less vivid here in Malta. However, social media is particularly rife with sapient cognoscenti who expound their opinions on the efficacy of the vaccine without a sherd of knowledge or science to their theories.

Prof Josef Lauri, mathematician and scientist explained to Newsbook.com.mt how authorities come to the conclusion on the efficaciousness of the vaccine. He took us through the process, step by step. He said that a corpus of knowledge on the virus’ family, corona, had already existed and Covid-19 is a variant of this family.

Vaccine vs Placebo

“The efficaciousness of the vaccine is tested in the third phase of the research. In this phase the vaccine ‘exits’ the confines of the laboratory and is administered to volunteers,” said Prof Lauri. Massive numbers volunteered for the Covid vaccine. Those chosen had to be representative of as wide a variety of ethnicities, gender, age groups, health conditions etc. “For these trials, volunteers were chosen from the four corners of the world in clinics all over the globe,” said Prof Lauri. After this choice is made, the volunteers are then split into two groups. One will be given the trial vaccine and the other a placebo. The placebo looks identical to the medicine being tested but contains no medicinal.

Number crunching

“Where trials are concerned, this area is very sensitive. Only the top researchers know who has been administered the placebo and who the trial vaccine – not the volunteers and not the doctors,” said Prof Lauri. He then launched a practical example on a sample of 30,000 volunteers. 13,000 will be given the placebo and 17,000 the trial vaccine. The 30,000 will then get on with their lives, receiving regular monitoring from the doctors who would have inoculated them. This monitoring may go on for days, months and even years after the medicine is in production.

“So, at some point, a date is fixed to see how many of the volunteers got the virus. Let’s say 110 got sick – 15 of those vaccinated and 95 of those with the placebo. Some mathematics will help here: 95 out of 13,000 is 0.73% while 15 out of 17,000 is 0.09%. Now divide 0.09 by 0.73. This gives you 0.12 – keep that number in mind. The vaccine is always considered to have a value of 1. So, subtract 0.12 from 1 and you get 0.88. That means that, scientifically, the vaccine is 88% efficacious. This, I repeat, is just an example,” said Prof Lauri.

Levels of efficacy

Prof Lauri said that when the results are higher than 80%, these are considered to be very good. The Smallpox vaccine, he added had no such trials and had only clinical estimates and yet smallpox has been eradicated. Polio too had an efficacy of 60-70% in general and 80-90% on the more resistant strains and this too was a great success story.

But, said Prof Lauri, a good vaccine is not everything, one must also have a good vaccination plan.

Prof Jeremy Ferrar, internationally acclaimed epidemiologist said that with the covid vaccine some countries had tried putting forward the nationalistic argument, claiming precedence in having supplies of the vaccine. Thankfully, he said, the world moved away from that. He added that medicine is one of the few truly ‘common goods’ and no one should expect precedence.

Prof Lauri cautioned “We need to ask how this medicine is going to reach the poorest countries and what the reaction of the public to it is going to be. Is the vaccine going to raise expectations to the extent that people will immediately throw away their mask and forget social distancing? If so, this could make matters worse in spite of the vaccine.”