September 25, 2022

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Israel: 4th dose of Pfizer vaccine has limited effect on preventing Omicron

Israel: 4th dose of Pfizer vaccine has limited effect on preventing Omicron



 

Israel: 4th dose of Pfizer vaccine has limited effect on preventing Omicron. 

 

 


Abstract:

Two weeks after inoculation, the antibody level in the test subjects increased, but the protective effect on Omicron was limited.

 

From the first dose, to the second, third, and fourth doses, in order to cope with the ravages of the new coronavirus mutant strains, the world is constantly updating the vaccination plan.

However, as the first country in the world to administer the fourth dose nationwide, a preliminary study released by Israel on the 17th showed that the fourth dose of the COVID-19 vaccine jointly developed by Pfizer and BioNTech had limited effect.

 

Israel: 4th dose of Pfizer vaccine has limited effect on preventing Omicron. 

 

 

 

Relatively little protection

According to a Reuters report on the 17th, 154 medical staff at the Sheba Medical Center in Tel Aviv, Israel, participated in the trial.

At present, this is only the preliminary research results and has not been officially released.

 

The researchers found that two weeks after the fourth dose of Pfizer’s vaccine, antibody levels in the test subjects increased, but the protection against Omicron was limited.

 

The lead investigator of the trial, Gili Regev-Yochay, said that after the fourth dose of Pfizer’s vaccine, the number of antibodies in the body was higher than that of the three doses.

However, the fourth shot provides only partial defense against Omicron, and is relatively less protective and more effective against the previous delta strain.

 

The study also showed that the test population who were still infected with Omicron after the fourth dose of the vaccine had only mild symptoms or no symptoms, which means that the fourth dose still has a significant effect in preventing severe illness.

 

The Israeli researchers also conducted a trial on 120 volunteers who received a fourth dose of the Moderna vaccine, who had previously received three doses of the Pfizer vaccine.

The results showed that a week after the trial began, people who received the Moderna vaccine had a similar increase in antibody levels compared to those who received the fourth dose of Pfizer’s vaccine.

 

Regev Uzia told the media that this is a good vaccine and that a fourth dose for the most vulnerable is the right decision because it may have additional benefits, but the findings do not support a nationwide promote this policy.

 

Israel is one of the fastest countries in the world to roll out a vaccine. At the end of December last year, as the number of cases of infection with Omicron surged, the Israeli government began to vaccinate the elderly over 60 years old and the immunocompromised group.

 

More than 500,000 people in the country have received the fourth dose, according to the Israeli Ministry of Health.

 

 

Vaccine strategy draws attention

As the global epidemic continues to spread, Omicron’s amazing transmission power is also worrying.

 

Many studies have shown that in the process of constant mutation, the virus can “learn” how to evade immunity, thus weakening the protective effect of the vaccine.

 

Existing research data shows that mRNA vaccines have a 90%-95% preventive effect on the initially discovered new coronavirus. But for the mutant strain “Delta”, the preventive effect of two doses of the Moderna vaccine dropped to 87%.

Data from the South African study also showed that the preventive effect of two doses of the Pfizer vaccine against Omicron dropped to 33%. Of course, the efficacy of vaccines is still very significant in preventing severe illness and hospitalization rates.

 

The popular science magazine “Scientific American” recently wrote that these data have sparked discussions on vaccine development strategies, including the need to produce targeted vaccines for specific mutant strains.

 

Last week, Pfizer announced that a vaccine against Omicron may be available in March, and the vaccine is currently in production.

 

One view is that, given that existing vaccines remain effective in preventing severe illness and death, tailor-made vaccines are of little use.

 

Some experts pointed out that the introduction of vaccines takes time, but the speed of virus mutation may be faster than the speed of vaccine development.

Therefore, the current strategy of “chasing virus strains” for vaccines may develop into a “game of whack-a-mole”.

 

According to experts, it usually takes 4-6 months to develop a vaccine, but it only took 2 months for the Beta mutant strain to appear and disappear.

Omicron was detected in South Africa last November, but the number of cases in South Africa has now declined.

 

Some research institutions believe that new strains other than Omicron may appear in the next few months, and developing a universal vaccine may be a better direction than a targeted vaccine, which can deal with unknown mutant viruses.

 

 

 

Israel: 4th dose of Pfizer vaccine has limited effect on preventing Omicron

(source:internet, reference only)


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