FRIDAY, June 25, 2021 (HealthDay News) -- More than 1 in 10 Americans have missed their second dose of a coronavirus vaccine, a troubling trend as the more infectious Delta variant that first crippled India gains a foothold in this country.
Only 88% of those who had received one dose of vaccine and were eligible for their second shot had actually completed the two-dose series, CNN reported. That's down from a 92% completion rate earlier in the year.
Studies have shown that the two-dose vaccines are much less effective against the Delta variant with only one dose of vaccine.
"As this virus has mutated, there are versions of it which are better able to escape some of the immune protection that we get from the vaccine," U.S. Surgeon General Dr. Vivek Murthy told CNN's Anderson Cooper, citing research that found two doses of the Pfizer vaccine offered 88% protection, compared to just 33% protection after just one shot.
"The key is, get vaccinated. Get both doses," Murthy said.
Experts warn that the Delta variant may soon become the dominant strain in the United States.
That could happen within weeks in under-vaccinated areas, Dr. Anthony Fauci said Wednesday, CNN reported. Data from the U.S. Centers for Disease Control and Prevention shows that the Delta variant may already account for more than 1 in 5 new COVID-19 cases, a rapid increase from fewer than 1 in 10 two weeks earlier.
That leaves millions of partially vaccinated people at risk as the Delta variant continues to spread through the United States, along with the 46% of the country's population that has not been vaccinated at all, CNN reported.
Adults under the age of 30 were most likely to have missed their second dose, with nearly 12% outside of the 42-day allowable window, CNN reported.
Officials have said that adults under 26 are the only group expected to miss the Biden administration's goal to vaccinate at least 70% of adults with at least one dose by July 4.
And CDC studies published this week found that younger adults lag others in vaccination intent, too.
Those in the 30-to-39 age group were also more likely to miss their second dose, according to the CDC data. But children under the age of 18 were least likely to miss their second dose, with only about 5% outside of the allowable interval, CNN reported.
FDA to add heart risk warning to Pfizer, Moderna vaccines
The U.S. Food and Drug Administration said this week that it will add a warning to the Pfizer and Moderna coronavirus vaccines about mild, rare cases of heart inflammation seen in some teens and young adults following vaccination.
The news came after a meeting of an advisory panel to the U.S. Centers of Disease Control and Prevention, where experts said the data suggests a "likely association" between the mRNA vaccines and rare cases of myocarditis/pericarditis -- an inflammation of the heart muscle or surrounding membrane.
The second dose of the Pfizer vaccine was linked to about twice as many cases as the second dose of the vaccine made by Moderna, The New York Times reported. And more than half of the heart problems occurred in people aged 12 to 24, even though that age group accounted for only 9% of the millions of doses given to Americans.
Despite the warning, top U.S. government health officials, medical organizations, laboratories, hospital associations and others released a joint statement on Wednesday stressing the overriding benefit of the vaccines.
"The facts are clear: this is an extremely rare side effect, and only an exceedingly small number of people will experience it after vaccination," the statement said. "Importantly, for the young people who do, most cases are mild, and individuals recover often on their own or with minimal treatment."
The statement also noted that "myocarditis and pericarditis are much more common if you get COVID-19, and the risks to the heart from COVID-19 infection can be more severe."
The statement urged all Americans 12 and older to get vaccinated.
"We strongly encourage everyone aged 12 and older who are eligible to receive the vaccine under Emergency Use Authorization to get vaccinated," the groups said. "Especially with the troubling Delta variant increasingly circulating, and more readily impacting younger people, the risks of being unvaccinated are far greater than any rare side effects from the vaccines. If you get COVID-19, you could get severely ill and be hospitalized or even die. Even if your infection is mild, you or your child could face long-term symptoms following COVID-19 infection such as neurological problems or diminished lung function."
The heart problem appears to be most common in young men after they receive the second of two doses, but it is still rare: There have been 323 confirmed reports of the inflammation in people younger than 30, and the vast majority recovered from their symptoms, the Associated Press reported.
That risk "seems to me, and to many others, to be much lower than the risk of COVID," Dr. Brian Feingold, a University of Pittsburgh heart specialist who is not a member of the panel, told the AP.
There have been nearly 2,800 COVID-19 deaths among adolescents and young adults, and more than 4,000 youths have suffered a dangerous condition called MIS-C that appears to be linked to the coronavirus.
The expert panel did not vote to change its recommendation to the CDC that Americans as young as 12 get the shots. CDC officials said Wednesday that they plan to update their guidance to say that anyone who suffers heart inflammation after one dose of the vaccine can defer a second shot, the AP reported.
One of the first Americans diagnosed with vaccine-linked heart inflammation was Sean Morrison, a scientist in Dallas. Three days after his second dose, he developed intense pain in his chest that he said felt like a heart attack, the AP reported. He was hospitalized for four days as doctors investigated. They did not see any lingering effects, but they advised him to avoid exercise so his heart could recover.
Morrison, a stem cell biologist at the University of Texas Southwestern Medical Center, praised the vaccines as a crucial weapon in the battle against a virus that has killed about 600,000 Americans. But he also called for more research into the side effect, the AP reported.
The U.S. Centers for Disease Control and Prevention has more on COVID-19 vaccinations.
SOURCE: CNN: Associated Press; The New York Times