Cepljenje v domu Sv. Lenarta v Slovenskih goricah. Foto: Tamino Petelinšek/STA
Cepljenje v domu Sv. Lenarta v Slovenskih goricah. Foto: Tamino Petelinšek/STA

Is the vaccine safe?

A vaccine usually takes 10 years or more to develop. So how could we get a vaccine against the new coronavirus in one year?

There are several reasons.

All medicines go through demanding approval procedures. When vaccine development begins, scientists first examine the virus and investigate how the vaccine would work at all.

This phase alone can take years. In the new coronavirus, it was greatly shortened.

Scientists initially perform tests on cell cultures, and only then on animals such as laboratory mice. They then check the safety and effectiveness of the vaccine.

However, since humans are not mice, clinical trials in humans follow.

The safety of the vaccine is first tested on a small group of people. If they do not get sick, they expand the study to a larger number of volunteers. At each stage of testing, their number increases and eventually amounts to about 30,000 people.

At the same time, they begin to test the effectiveness of the vaccine, thus whether it protects people from infection at all. At the same time, they determine what dose of vaccine is most appropriate.

The phases of clinical testing usually follow one another, but this time they overlapped. This means that they tested the effectiveness and, above all, the safety of the vaccine in a very large number of people, and thus carried out all the clinical studies more quickly.

Moreover, the scientists had no trouble finding volunteers.

»Usually, selecting volunteers takes weeks or months. In this case, however, it happened overnight,« says Professor Adam Finn, a researcher involved in the development of the AstraZeneca vaccine in collaboration with the University of Oxford.

Funding was not a barrier because the vaccines were developed mostly by large companies with the support of many countries.

The [Slovenian] National Institutes of Public Health received one report of an adverse reaction after vaccination and a report of a death that coincided in time with the vaccination at a nursing home.

Points to Consider

  1. Why is so safety important?
  2. Would you be a volunteer in clinical trial?
  3. Do you know any other dangerous viruses?


The original version of this article was published on January 5th.

English translation courtesy of JL FlannerTotal Slovenia News, an English language website with news from and about Slovenia.


Adamič je diplomirana biotehnologinja, ki rada potuje po svetu in približuje znanost najmlajšim.

Vprašanje tedna


Ljubljana Slovenia

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