Hospital (illustrative)
Hospital (illustrative) iStock

One of the strains of influenza included in this year's vaccine may have undergone a chance affecting how effective the flu vaccine is against it, Israel Hayom reported.

This week, there was a 65% rise in the number of people diagnosed with influenza who are hospitalized. In the past two weeks, the number of people who arrived at local clinics suffering symptoms of flu has doubled.

This week, 730 people were admitted to hospitals with influenza, and there is concern that due to a drop in the vaccine's efficacy, these numbers will rise even more. According to the Israel Center for Disease Control (ICDC), a total of 1,849 influenza patients have been hospitalized this season, among them 605 children and 124 new and expectant mothers.

Most of the patients were infected with H3N2, or this year's "type A" strain, which is included in this year's flu vaccine. However, the strain has undergone a change, and recently-published research showed that under laboratory conditions, this year's vaccine is now less effective against it.

It also found that 15 people over the age of 75 have died after contracting influenza.

The Health Ministry noted that the flu vaccine can be administered to anyone over the age of six months, and that it can be received at the same time as the coronavirus vaccine. The Ministry also warned that, "Flu infections in Israel are on the rise. The influenza virus may cause severe illness. The Health Ministry emphasizes the importance of getting vaccinated against it."

Professor Michal Chowers, who heads the infectious disease clinic at Meir Medical Center, told Israel Hayom: "Every year they put out a new flu vaccine, and every year they make predictions regarding the four strains which will be included in the vaccine. Every few years the dominant strain changes, and then it is less compatible with the vaccine."

"It's as if you're planning a coronavirus vaccine for the alpha variant, and then Omicron comes. So that's why we estimate that the efficacy of the flu vaccine has dropped. The flu vaccine's efficacy ranges between 40 and 70 percent in preventing infections. But when it comes to preventing serious illness, the vaccine's efficacy remains stable."

Dr. Ira Zaretsky, an expert in immunology at the Weizmann Institute of Science, told Israel Hayom, "The increase in infections which we are seeing is not necessarily connected to the vaccine. Nearly every year at this time there is a rise in the number of hospitalizations. Despite the fact that there has been a drop in the vaccine's efficacy, we need to do everything in order to get vaccinated and protect ourselves."

Health Ministry data showed that so far, just 1.643 million Israelis have received this year's flu vaccine, representing 17.8% of the population; by the same period last year, 25% of Israelis had received the flu vaccine.