Millions of Americans are missing ‘critical’ second COVID-19 vaccine shot, according to CDC data

More than five million Americans have missed out on their second COVID-19 vaccine dose, according to the U.S. Centers for Disease Control and Prevention. 

According to the CDC, more than 95 million Americans have been fully vaccinated, representing 28.9% of the total U.S. population. The agency said the five million people who haven’t received their second dose within the recommended timeframe represent nearly 8% of those who got their first shot of either Pfizer or Moderna’s vaccine, meaning about 92% of people are completing their vaccine.

But the agency said it’s not surprising that people have skipped or missed out on getting their second dose.

"Overall, this increase in missed second doses was expected as eligibility expands to more people," the agency said in a statement to FOX Television Stations Tuesday. "The groups initially prioritized for COVID-19 vaccination were more likely to have been vaccinated at their work site (healthcare providers) or residence (long-term care facilities), potentially reducing barriers and increasing adherence to the recommended vaccine schedule."

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While it was expected, the agency said the exact reason for why people missed their second shot still needs further research. However, health officials maintain a second shot is very much needed to curb the pandemic. 

"Ensuring second dose completion of the vaccine is critical in helping to protect people from COVID-19," the statement continued.

But "vaccine hesitancy" remains a problem as the overall pace of vaccinations has slowed over the past several days. According to the Wall Street Journal, the country administered an averaged of 3.2 million shots a day in early April. That number has dipped to 2.8 million doses a day, according to the outlet.

CDC Director Rochelle Walensky said the agency is working to educate people about the science, data and safety of vaccines.

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"We believe and know that the science moved quickly. We’ve enrolled 100,000 people in these trials and the science stood on the shoulders of years and years of work before to be able to deliver these vaccines," Walensky told reporters Tuesday during a virtual news conference.

"If people are worried about the side effects, we can convey the data of over 200 million vaccine doses and the safety and the scrutiny of that safety," she continued. "So we need to meet people where they are and understand why they might be hesitant and then give them the information that combats that hesitancy."

But side effects of the vaccine are becoming a growing concern.

According to KTVU, a Bay Area man is under care at the University of California at San Francisco medical center after developing blood clots after receiving the Johnson and Johnson COVID-19.

RELATED: Johnson & Johnson vaccine: CDC lifts suspension amid blood clot concerns

His hospital stint came after U.S. health officials lifted an 11-day pause on Johnson & Johnson’s single-dose shot last week after scientific advisers decided its benefits outweigh a rare risk of blood clot. The government uncovered 15 vaccine recipients who developed a highly unusual kind of blood clot out of nearly 8 million people given the J&J shot. All were women, most under age 50. Three died, and seven remain hospitalized.

Another challenge is getting people to vaccination sites.

Last month, President Joe Biden announced a $10 billion initiative to help expand vaccine access to better serve communities of color, rural areas, low-income populations and other underserved communities. Some of the plans included setting up federally-run community vaccination centers in hard-hit areas, sending vaccines directly to local pharmacies and Community Health Centers that disproportionately serve vulnerable populations, and launching hundreds of mobile clinics to meet people where they are; and created the COVID-19 Health Equity Task Force.

RELATED: COVID-19 vaccine milestone: US surpasses goal of 200 million shots administered in less than 100 days

Several rideshare companies, such as Uber and Lyft, are also offering free rides to vaccination sites. 

President Joe Biden recently celebrated reaching his latest goal of administering 200 million coronavirus vaccine doses in his first 100 days in office.

Biden also announced a tax credit for small businesses to provide paid leave for those getting vaccinated or potentially needing to take time off to recover from side effects. Paid for through the $1.9 trillion virus relief package, the tax change will provide a credit of up to $511 per day, per employee for businesses with fewer than 500 workers to ensure that those workers or businesses don’t suffer a penalty by getting vaccinated.

He predicted Americans could safely gather at least in small groups for July Fourth to "make this Independence Day truly special."

The Associated Press contributed to this report. This story was reported from Los Angeles.