(Reuters) – The fourth dose of BioNTech/Pfizer vaccine lowered COVID-19 rates among seniors, but it did not protect against infection. This was confirmed by a large Israeli study.

Israeli researchers published their findings in a study in Tuesday’s New England Journal of Medicine. They found that the second booster has lost its ability to protect against infection after just four weeks.

Researchers said that although protection against severe illnesses did not decrease in the six-week period following the administration of the drug, more research was required to assess its long-term effectiveness.

This study of over 1.3 million older people looked at data taken from the Israeli Ministry of Health Database between January 10, and March 2, during which the Omicron variant prevailed.

This announcement comes before a U.S. Food and Drug Administration meeting on Wednesday, to discuss the necessity for additional boosters. It follows a week in which the United States authorized a second booster shot for those 50 and over due to a widespread Omicron subvariant BA.

European health ministers also called on the countries of the bloc for a fourth dose to be approved by people older than 60.

South Korea has begun to give fourth doses COVID-19 vaccines across Asia in February. Singapore also announced that it is planning to offer a second booster for patients 80-plus.

An Israeli study found that seniors who were given a second boost of testosterone last month had a higher chance of surviving. Pfizer (NYSE:) The death rate for those who received the Inc/BioNTech SECOVID-19 vaccine was 78% less than that of people who had only one.

Israel offered a second boost in January.