(CNN) Millions of people in the United States are behind on their Covid-19 vaccinations, and millions more have missed other routine vaccinations throughout the pandemic.
Long before the coronavirus, public health officials were concerned about low levels of routine vaccinations that are recommended by the US Centers for Disease Control and Prevention for adults and adolescents for diseases like flu and HPV. A sharp drop in uptake over the two years of the pandemic has cut into the progress that has been made.
Adults and adolescents have missed more than 37 million routine vaccinations during the Covid-19 pandemic, according to an analysis of insurance claims by Avalere, a health care consulting firm.
The firm compared monthly claims from January 2020 through June 2021 against baselines from 2019. On average, the analysis found, monthly claims were down 32% for adults and 36% for adolescents compared with 2019. Vaccinations ticked up briefly in March 2021 but otherwise consistently lagged behind 2019 levels in all markets.
Along with flu and HPV, vaccinations tracked in the analysis included hepatitis, chickenpox and shingles, MMR (measles, mumps and rubella), meningococcal, pneumococcal and Tdap (tetanus, diphtheria and pertussis).
In the US Department of Health and Human Services' Healthy People 2030 plan, one goal in development is to increase the share of adults who receive recommended age-appropriate vaccines.
"We were increasing coverage rates pretty consistently every year, and we wanted to do more," said Claire Hannan, executive director of the Association of Immunization Managers.
Improving vaccination coverage for flu and HPV are particularly of high priority, she said.
Meningitis and Tdap are required by schools in most states, and coverage rates tend to be higher. But with flu and HPV, there's a "lack of urgency," and coverage rates were among the lowest.
As with Covid-19 vaccines, experts say that recommendations from health care providers -- including primary care physicians, nurses and pharmacists -- are one of the most effective ways to boost vaccination rates in general.
The CDC recently published an outline of strategies to increase adult vaccination rates that was drafted by members of the National Adult and Influenza Immunization Summit and that served as a call to action to health care providers.
"Their recommendation remains the number one reason why people get vaccinated," said Dr. L.J. Tan, summit co-chair, chief policy and partnerships officer for immunize.org, and former liaison to the CDC's vaccine advisory committee for the American Medical Association.
And Tan says the drop in routine vaccinations will come with costs in the years to come.
"The biggest challenge here is an increase in vaccine-preventable diseases. We'll see outbreaks. We'll see surges of increased morbidity because of increased disease. And we'll see increased costs to the health care system," he said.
"When you couple it with Covid, we might see increased demand on the capacity of the health care system."
Between January 2020 and June 2021, adolescents ages 7 to 18 missed a total of about 10 million routine vaccinations, and adults age 19 and older missed a total of about 27 million vaccinations since January 2020, according to the Avalere analysis. Overall, those insured by commercial insurance plans accounted for nearly two-thirds of missed doses.
Experts stress the importance of getting up to date as soon as possible.
"Go get that vaccine that you're missing. Catch up on the series. Have you started something, but you haven't finished the series? Go finish it now. If you're due for something that you haven't even started, go get it now," Tan said. "Now is the time to get caught back up again."
Getting a flu shot now can still make a difference in the current season, he said.
And as Covid-19 continues to circulate at an extremely high level in the US, keeping up with other routine vaccinations can help ease stress in a time of uncertainty.
"Routine vaccinations should give peace of mind," Hannan said. "We know these vaccines work."
The analysis by Avalere -- and funded by GlaxoSmithKline -- used millions of de-identified patient records captured in a clearinghouse database. The datasets capture 42% of the US population insured by commercial plans, 69% of the Medicaid population, 25% of the Medicare Advantage population and less than 10% of Medicare Fee-For-Service claims nationwide.