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.

Scientists pinpointed 16 new genetic variants in people who developed severe COVID-19 in a large study published on March 7 that could help researchers develop treatments for very sick patients.

A large study into rare blood clots linked with AstraZeneca’s COVID-19 vaccine found between just one and three cases per million, and only after the first dose, shedding fresh light on the side effects from the shot.

Scientists believe they have found the likely cause of blood clotting in some recipients of the Oxford-AstraZeneca Covid-19 vaccine.

In line with growing concerns that certain Covid-19 vaccines are causing unusual blood clotting problems, a group of scientists from the U.K. conducted a massive study on the link between vaccinations and dropping platelet counts and found that the problem lies more on the virus itself than on the medications. 

The U.S. Food and Drug Administration approved Abbott’s Amplatzer Amulet Left Atrial Appendage Occluder to treat people with atrial fibrillation (AFib) who are at risk of ischemic stroke.

AstraZeneca’s Covid-19 vaccine carries a small extra risk of rare blood clots with low platelets after the first dose and no extra risk after the second, a study led and funded by the drugmaker showed on July 28, after worries over side effects.

Two new cases of blood clots after administration of Johnson & Johnson’s single-dose Covid-19 vaccine are being investigated by federal health officials, the U.S. Centers for Disease Control and Prevention said on April 27.

The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) lifted the restrictions on the Johnson & Johnson Covid-19 vaccine on April 23. The announcement came after the FDA’s Advisory Committee on Immunization Practices (ACIP) met for a second time to discuss the data, with the benefits outweighing the risks.

Johnson & Johnson said on April 20 the company will resume rolling out its Covid-19 vaccine in Europe after the region’s medical regulator said the benefits of the shot outweigh the risk of very rare, potentially lethal blood clots.