Scientists: Two doses of Pfizer / BioNTech vaccine are not enough

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A new Israeli study published in Nature Communications shows that people vaccinated with two doses of the Pfizer / BioNTech coronavirus vaccine in January and February are 51% more likely to be infected with the virus in July than those who were vaccinated in March or April.

The KI Institute team of researchers worked with doctors from KSM Research and Innovation and used data provided by Maccabi Health Services to conduct a retrospective cohort study comparing the incidence of breakthrough infections and COVID-19-related hospitalizations among people vaccinated in the beginning of the campaign in the country, and those vaccinated to later stages. The survey includes more than 1.3 million records.

As noted, the risk of infection was significantly higher for people who had been vaccinated earlier, with an additional tendency for a high risk of hospitalization. The results, according to the researchers, are in line with other studies on the subject, which show a decrease in the levels of antibodies and compounds of the immune system after four to six months, BGNES reports.

In addition, the age of the people did not affect the weight loss of the vaccine, which means that the vaccine has lost weight for everyone, not just the elderly.

“According to the study, the effectiveness of the vaccine is declining equally for everyone,” said Dr. Barak Mizrahi, a researcher for the KI Institute, which is leading the study.

Israel has adopted a policy of giving a third injection to all people over the age of 12, unlike many other countries, and the World Health Organization’s recommendation to give a third injection only to people at the highest risk of contracting the virus or developing severe disease.

More than four million Israelis have received a booster vaccine. The results are that the infection rate has decreased significantly.

Mizrahi explained that the vaccine weakens as it moves away from the initial second dose, which means that people vaccinated in January were more at risk of contracting the coronavirus than people vaccinated in February, and so on.

The study was conducted when the Delta strain covers the whole country and many believe that this option may be the cause of the increased number of infections in Israel. Mizrahi said the study shows that the option was probably a smaller factor than previously thought – although this has not yet been confirmed.

Mizrahi said that at this stage it is difficult to say whether the third dose will work longer. Various preliminary studies have begun to collect evidence that antibodies weaken after the third injection. However, he said the level of antibodies is not the only factor when it comes to immunity. Officials will need to monitor whether infections begin to increase and then determine appropriate vaccination policies, Mizrahi said.



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