Doctor and senior woman wearing facemasks during coronavirus and flu outbreak. Virus protection. COVID-2019..

Four flu vaccine manufacturers are expected to have a record number of doses available for the upcoming season, according to the Food and Drug Administration. Seniors are the age group hardest hit by the flu each year.

A total of 100 million doses should be available for the 2006-2007 season, the FDA said, barring any unforeseen challenges or circumstances. This number would end years of flu shot shortages and production delays, officials said.

Last week, the FDA approved vaccines that will protect against three strains of seasonal flu. The seasonal formulation includes one strain used in last year’s vaccines and two new strains. The following manufacturers received approval to sell flu vaccines in the United States: Chiron Corp., GlaxoSmithKline PLC, MedImmune Inc. and Sanofi Pasteur SA.