How vaccine tests are conducted

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

15 November 2020

Health Cabinet Secretary, Mutahi Kagwe caused a stir when he expressed doubts about the validity of the announcement by the American pharmaceutical company, Pfizer Inc., that they had developed a vaccine for Covod-19.  In an interview on NTV, CS Kagwe wondered: “A drug that stops people from getting the virus?

‘…If we are talking about treatment, when I have the virus and it goes down, I can understand the measure. But when you tell me you stopped me from getting the virus, how did you know I was going to get it in first place?”

These remarks were very unfortunate. Coming from none other than the country’s head of health, they put doubts on all vaccination programmes. For that reason, I feel duty-bound to explain how vaccine tests are conducted.

I wrote bout it 14 years ago in December 2006. In that instance, researchers had announced that circumcised men are less likely to contract HIV through sexual intercourse than uncircumcised ones. People wondered: were the men in the study forced to have sex with HIV-positive women?

Well: Of course not! As I wrote in 2006: “That would be illegal and unethical. The way to go about it is to select a random group of men that is in similar circumstances except that some are circumcised and others are not.

“The researchers in this case surveyed a total of 7,780 men half of whom were circumcised. The group comprised of 4,996 Ugandans and 2,784 Kenyans. They found that 90 (43 Ugandans and 47 Kenyans) of the uncircumcised men contacted HIV during the period of the study while only 44 (22 Ugandans and 22 Kenyans) in the other group got the virus positive.”

A vaccine test uses a similar methodology. A random sample of people is selected and divided into two groups. One group gets the active vaccine while the other gets a placebo – a formulation that looks, tastes, smells like the vaccine but it does not contain the active ingredients.

These people are then released to go about their lives in the normal way – in the case of covid-19, they can take precautions just like the rest of us. After some time, they are tested to see the rate of infection.

If the group that got the active drug has a lower infection rate than the one that got the placebo, then this will be evidence that the vaccine works. Of course, the study will have margins of error depending on the size of the sample.