A fourth dose of mRNA vaccine is difficult to stop Omicron infection

On the evening of January 17, local time, Israel's Jerusalem Post and other media reported that the preliminary results of the world's first clinical trial of the fourth dose of new crown pneumonia vaccine carried out by the country's Sheba Medical Center showed that it was difficult to prevent the infection of the Olmikron strain by the fourth dose of mRNA vaccine produced by Pfizer.

Professor Gilly Regoff-Yukai, principal investigator of the clinical trial, said the existing vaccine was very effective against previous strains but less effective against the Olmikharong strain. The fourth dose increases the antibody and is slightly higher than the third, but many people are still infected by the Aumechjong strain after receiving the fourth dose. Compared to the control group, the number of infections was slightly lower, but there was no significant decrease.

As for the specific number of infections, the level of antibodies after vaccination and the preventive effect of the fourth dose of vaccine on severe diseases, Regoff said that it is still under study and cannot be provided for the time being, and the preliminary results are now released.

Despite the poor results of the trial, Regoff believes that it may still be correct to offer a fourth dose of the vaccine to high-risk groups such as the elderly, and that the fourth dose will bring some benefits, but these benefits will not be enough to support the plan to make it available to everyone.

Sheba Medical Center launched the trial on December 27 last year to administer the fourth dose of Pfizer to 150 healthcare workers who had received the third dose of the vaccine for more than four months and whose serum antibody levels were below 700. Subsequently, the centre conducted a similar trial in which a fourth dose of the Modena vaccine was given to an additional 150 health workers. Regoff revealed that antibody levels after receiving the two vaccines were similar.

In early January, Regoff said that antibody levels had increased fivefold after a week of vaccination with the fourth injection. The results were similar to those given after the third dose and did not meet the expectations of the trial. A week later, she again said that while antibody levels had increased further, they did not appear to be enough to combat the infectivity of the Aumecreon strain.

Israel is currently providing a fourth dose of COVID-19 vaccine to people over the age of 60, immunocompromised people and healthcare workers, with nearly 540,000 people vaccinated across the country. However, Israel is still trapped in the peak of the epidemic brought by Omicron, with an average of more than 40,000 new confirmed cases in a single day last week. (Reporter Hu Dingkun)

Source: Science and Technology Daily