Share on Pinterest
Experts say several million fewer Americans than anticipated will be vaccinated by July 4. Irfan Khan/Los Angeles Times via Getty Images
  • Experts say the United States missing its goal of a 70 percent vaccination rate by July 4 means several million fewer Americans will have received at least 1 dose of vaccine by the holiday.
  • Experts note that the threshold for herd immunity for COVID-19 is shifting due to the emergence of more contagious coronavirus variants.
  • They say the United States should look at past successful vaccination campaigns against diseases such as polio and mumps to determine how to best fight COVID-19.

In May, President Joe Biden appealed to Americans’ patriotism in the fight against COVID-19 by rallying the country to hit a 70 percent vaccination threshold by July 4.

Turns out, we’ll fall just short: Somewhere around 67 percent of adults in the United States will have received at least one dose of COVID-19 vaccine by Independence Day on Sunday.

Close but not an insignificant gap.

“While 2 to 3 percent sounds like a relatively small shortfall, it represents 3.4 to 5.2 million adults who are unvaccinated,” Hannah Sally, a senior epidemiologist for Informa Pharma Intelligence, told Healthline.

“Considering that the current rate of vaccination stands at about 1 million doses per day on average, we may assume that it would only take a week or so past the deadline to reach the 70 percent goal,” she said.

Which still likely won’t be enough.

There are many factors complicating the idea of herd immunity against COVID-19 and estimates vary as to what percentage of vaccinated Americans will get us there.

Sally said a major variable is a relative lack of fear in young people, which is helping keep the number of vaccinations lower than it should be.

Sally notes that only about 49 percent of 18- to 24-year-olds have received at least one dose, compared with more than 85 percent of people 65 years and older.

“Vaccine reluctancy in younger adults poses a major challenge and may impede the progress toward reaching the 70 percent goal,” she said.

Experts say initial estimates of herd immunity coming at a vaccination rate of 60 to 70 percent was wishful thinking. Things have changed.

“The development of coronavirus variants has, among other things, increased the reproductive number R of the SARS-CoV-2 virus,” Dr. Robert Quigley, the global medical director of health and security at International SOS Assistance, told Healthline.

“As a result, herd immunity — through infection or vaccination — will continue to be difficult to achieve,” he said.

“No doubt the delta variant, which is not only highly transmissible but results in more severe illness, remains a constant threat,” Quigley said. “Particularly among unvaccinated Americans. There is no number that will categorize the feeling of being past the pandemic.”

“There are regions and communities in which low vaccination rates will continue to be a risk, even once the national threshold has been reached. We will continue to see coronavirus variants popping up in the United States,” he said.

Variants are an evolving problem, making the future difficult to predict.

“Delta is said to be more transmissible than alpha, which was already 50 percent more transmissible than the parent strain,” Dr. Supriya Narasimhan, the chief of infectious diseases at Santa Clara Valley Medical Center in California, told Healthline.

“Public Health England estimates that delta is 64 percent more infectious than alpha. Modeling estimates suggest we may need to approach 85 percent of greater immunity rates to have herd immunity against the delta variant,” Narasimhan said.

“But really, we are in a race to vaccinate against the virus and variant evolution,” Narasimhan said.

Dr. José Mayorga, an assistant clinical professor of family medicine at the University of California at Irvine, told Healthline that history shows how we can beat COVID-19.

“If you think about what other communicable diseases we have been able to eliminate in the United States with vaccines, it’s been due to a high uptake in vaccine rates,” he said.

“Good examples are polio, mumps, and tetanus. What happens when we do not have a large percentage of the country vaccinated, or if rates of vaccination dip a little? Communicable diseases return and cause micro-outbreaks,” Mayorga said.

“A case in point is measles,” Mayorga said. “We’ve heard in recent years there have been measles outbreaks due to a lowering/waning of vaccination rates. This has tremendous consequence to everyone.”

He notes that vaccinating 2 percent fewer people for measles, COVID-19, and other communicable diseases can have a significant impact.

“This helps us all, especially those who can’t get the vaccine. We literally build an imaginary wall around our young children so that these viruses can’t attack them,” he said.