Four vaccinations against Covid-19 are more effective in reducing deaths and in preventing severe illness than three vaccinations. This is the conclusion of two studies, by the Clalit health fund and by the Maccabi health fund's KSM Research and Innovation Center, released at the end of last week.
In the Clalit study, the fourth vaccination was found to reduce fatalities by 78% during the Omicron variant wave, while the KSM study found a 73% reduction in severe illness, among those who had received four vaccinations, in comparison with those who had received only three.
The observational studies were complicated, since during the studies some participants underwent vaccinations and moved from one group to the other, but through complex statistical analysis, the researchers were able to overcome this problem.
Dr. Doron Netzer, head of community health at Clalit Health Services, said, "The results of the study that we carried out show unambiguously that the second booster shot is clearly associated with reduced risk of dying from Covid-19, including from the Omicron variant. The results mean that the decision by the Ministry of Health to recommend an additional vaccination dose for old people even before the matter had been examined in research saved the lives of many people in Israel, with a reduction of nearly fivefold in the risk of mortality in this population."
The KSM Research and Innovation Center said that the effectiveness of the vaccination against severe illness was maintained throughout the period of its study. That is to say, there was no appreciable fading of protection against severe illness (although the researchers point out that the group of severely ill people was in any case small, and so this specific conclusion is weak).
As far as infection is concerned, the picture is a little different. Three weeks after a fourth vaccination dose, there is a 64% decline in the risk of becoming infected, in comparison with those who have had only three doses, and that is the peak of effectiveness in preventing infection. After ten weeks, the extra effectiveness in preventing infection is 29%.
Omicron-specific vaccine still at trials stage
Last week, the European Medicines Agency announced that it expected initial information from the trial by Pfizer of a specific vaccine for the Omicron variant "sometime between April and early July." It is thus impossible to know at the moment whether this information will still be relevant during the current wave of the disease in Europe, and the vaccine itself will probably not become available before the wave of infection with the BA 2 Omicron sub-variant weakens substantially.
Moderna began enrolling people for a trial of its specific vaccine only at the beginning of March. It would appear that neither company is enthusiastic about its specific vaccine, and neither is pushing hard on it, presumably because both assume that by the time the vaccine is available the virus is liable to have mutated again, while it will still be possible to sell the original vaccine. It is not clear how relevant the specific vaccine developed against the BA 1 sub-variant will be against the BA 2 sub-variant. If it turns out that it is effective, people at high risk may be recommended to arm themselves with this vaccine as well, in order to strengthen protection against future Omicron sub-variants.
Meanwhile, the world is getting through the Omicron wave without a specific vaccine, and the price is widespread morbidity and death (although a large proportion of the cases of severe illness and death is among people who have not been vaccinated). It may be that in the future the trials track for bringing a specific vaccine to market will need to be shortened, in order for it to become available in time.
Published by Globes, Israel business news - en.globes.co.il - on March 27, 2022.
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