Health authorities around the world are investigating a mysterious increase in severe cases of hepatitis – inflammation of the liver – in young children.

A fourth dose of the COVID-19 vaccine from Pfizer and BioNTech provided significant added protection against severe disease, hospitalization and death for at least a month in older individuals, according to a study from Israel conducted when the Omicron variant was dominant. Additionally, new findings suggest patients with COVID-19 may have an increased risk of rare vision-threatening blood clots in the eye for months afterward.

A fourth dose of the Pfizer/BioNTech vaccine lowered rates of COVID-19 among the elderly but the protection against infection appeared short-lived, a large study in Israel found.

Senior citizens who received a second booster of the Pfizer-BioNTech COVID-19 vaccination had a 78 percent lower mortality rate from the disease than those who got one only, a study from Israel showed on March 27.

Pfizer Inc. and the company’s German partner BioNTech SE on March 15 filed an application with U.S. regulators seeking emergency use authorization for a second booster shot of their COVID-19 vaccine for people aged 65 and older.

Researchers at Bar-Ilan University and the Galilee Medical Center identified an association between vitamin D deficiency and severity and mortality of COVID-19.

Two cases of a subvariant of the Omicron variant were identified in Washington state. Two cases were also identified in Houston.

A fourth dose of COVID-19 vaccine given to people over 60 years in Israel made them three times more resistant to serious illness than thrice-vaccinated people in the same age group, Israel’s Health Ministry said on January 23.

A fourth shot of COVID-19 vaccine boosts antibodies to even higher levels than the third jab but it is not enough to prevent Omicron infections, according to a preliminary study in Israel.

The U.S. Centers for Disease Control and Prevention (CDC) said on January 5 the agency expanded the eligibility of Pfizer Inc. and BioNTech SE’s booster doses to those 12 to 15 years old.