Many U.S. adults did not get their recommended immunizations during the pandemic in 2020, according to a new analysis of insurance claims from vaccine maker GlaxoSmithKline. 

In total, 26 million doses of federally recommended vaccines were missed in 2020, including 17.2 million missed adult vaccine doses. And immunizations continue to lag well behind 2019 levels, according to GSK’s report. Adults’ non-influenza vaccine claims dropped between 17% and 40%.

An August-September surge in influenza immunizations, meanwhile, may suggest awareness of a possible “twindemic” of flu and COVID-19. But that surge leveled off and then fell in November, so that the 2020 flu immunization rate among adults lagged behind 2019’s rate as well.

“Even small drops in immunization rates can lead to a resurgence of disease as was demonstrated by the 2019 measles outbreaks,” GSK cautioned in a statement last week. 

“Teens and adults missed millions of doses of recommended vaccines during the pandemic; the cumulative impact grows like a snowball each day,” said Thomas Breuer, chief medical officer at GSK Vaccines. “As life returns to normal, we must prioritize getting individuals caught up on their missed vaccines.”

Recommended vaccinations for older adults include those for pneumonia, shingles, influenza and hepatitis A, along with the diphtheria, tetanus and pertussis (Tdap) vaccines.

The Centers for Disease Control and Prevention recently changed its vaccine co-administration guidance. “Out of an abundance of caution,” the agency previously had recommended that COVID-19 vaccines be administered alone, at least 14 days before or after administration of other vaccines. It now states that COVID-19 vaccines can be administered safely without regard to timing of other immunizations.

The GSK analysis was conducted by Avalere using Medicare fee-for-service claims and a large-scale dataset that included medical, pharmacy and lab claims and clinical data on more than 336 million patients.