European regulators concluded on Wednesday that it is “too early” to administer second booster shots of a coronavirus vaccine to the general population in the European Union, but added that the extra doses could be given to adults aged 80 and older.
The European Medicine Agency and European Center for Disease Prevention and Control said that data from Israel indicated that there was an increased risk of severe illness and a lower immune response to vaccination among people aged 80 and older.
Israeli data also suggested that a second booster, given at least four months after the first, saw antibody levels replenished without raising further safety concerns, European officials said.
But for most adults with healthy immune systems, the officials added, there was no clear evidence that protection against severe disease afforded by vaccines was diminishing.
Looking at the same data from Israel, the U.S. Food and Drug Administration announced last week that Americans aged 50 and older and some others could receive a second booster four months after their first booster shoots. The U.S. Centers for Disease Control and Prevention also encouraged second boosters for those groups.
“There is no clear evidence at the moment that vaccine protection against severe disease is waning substantially in adults between 60 and 79 years of age with a normal immune system, to support the need of a fourth dose,” Andrea Ammon, the E.C.D.C. director, said in a video statement.
“Nevertheless, national authorities should closely monitor the population experiencing severe Covid-19, and decide to use a fourth dose if there are signals of increasing risk among those who already received the third dose,” she said, referring to the 60-to-79 age group.
For healthy adults younger than 60, there was yet “no indication” that an additional booster dose would be of value, Ms. Ammon added. The agencies said they would continue to review evidence and update recommendations as necessary.
A fourth dose has already been recommended by the European health agencies for immunocompromised individuals who have had a “suboptimal response to earlier vaccination.” In the United States, federal regulators said last week that those 12 and older with certain immune deficiencies are also eligible for a second booster.
In March, a second Covid-19 vaccine booster was approved in England for around five million vulnerable people. Anyone over age 75 or over age 12 with a suppressed immune system, or who resided in a nursing home, can receive a second booster dose around six months after their first one.