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Study: the third dose of Comirnaty prevents death, severe disease and hospitalization

The third dose of Comirnaty vaccine by Pfizer BioNTech boosts the protection against COVID-19 remarkably, is concluded in the study conducted in Israel.

People at the age of 16 and older who had their second dose of vaccine at leats five months ago were included in the study. Another condition was that, as far as they knew, they hadn't contracted SARS-CoV-2 virus before.

People were divided into two groups, both of them had 782 321 participants. Every person who had the third dose, was match with someone as similar from the control group (the time of the jab, age, sex, etc) to compare them with.

Doses were given from the 30th of July to the 23rd of September. From the seventh day, the number of contractions were studied. The indications were people who needed hospitalization, had a severe case of COVID-19, or died because of that illness. After analysing the indications, it was concluded:

  1. Out of people who had two doses of vaccine, (control group) 231 ended up in the hospital, but from people who had the third dose, only 29 ended up in the hospital. Therefore, the effectiveness of preventing hospitalization is 93%.
  2. From the control-group, 157 people had a severe case of COVID-19, but in people with the booster dose, only 17 had a severe case. Therefore, the effectiveness of preventing the severe cases is 92%.
  3. In the control group, 44 people died because of COVID-19, but in people with the third dose, 7 people died. So, the effectiveness of preventing deaths because of COVID-19 is 81% with the booster dose.

In both study groups, contractions were observed. In the control group, 6131 people caught the virus, and 3345 developed symptoms. In people who had three doses of vaccine, these numbers were 1135 and 514, so the effectiveness of the vaccine 88 and 91%, accordingly. The authors of the study emphasize that because the testing frequency was different, this data can't be assessed impartially.

Also, it's mention worthy that the differences were bigger in the age group 40 years and older because among 16-39 year olds there were too little severe cases. Also, serious side effects of the vaccines were not researched.

It is not known yet, when the full protection is achieved after the third dose and how long it will last. Even then, it's proved that the third dose of the BNT162b2 (Comirnaty) increases the immunity against SARS-CoV-2 effectively.

The study was published on the 29th of October in a science magazine, The Lancet. You can read it here.

Source: Estonian Agency of Medicines

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