Approximately 83% of the U.S. population 16 years of age or older has some degree of immunity to coronavirus against vaccination or previous infection, according to a study by the new Centers for Disease Control and Prevention (CDC).
According to antibody levels in approximately 1.4 million patient blood samples, CDC researchers estimated that 20% of Americans have immunity to previous infection, although the number varies with age. and other demographics. The other 60% have received a trait that confers similar immunity.
Experts previously cited 70 to 80 percent protection as a target for herd immunity, but now many say we need more vaccines and boosters to protect us from the super contagious variant of the Indian Delta.
However, the study indicates that the United States has had many more Covid cases than have been officially reported, possibly more than double the official count.
A new study estimates that more than 80% of Americans over the age of 16 have some degree of protection against Covid. Pictured: Vaccination at a Central Falls Institute, Rhode Island, February 2021
As of May 2021, 20% of Americans over the age of 16 are protected from a previous infection, while an additional 60% are protected from vaccination, according to researchers.
As of September, 2.175 billion Americans are fully vaccinated, meaning they are protected from serious Covid diseases.
But millions of others are also protected to some extent, because they recovered from a previous Covid case.
As you fight the coronavirus, a body’s immune system will remember how to react to this invader and will be better prepared for future Covid encounters.
The CDC has about 39.5 million Americans who have become ill with Covid, or 39.5 million people with some degree of potential immunity.
The actual number is likely to be much higher, however, because many people with mild or no cases did not know how to take the Covid test and therefore never registered.
A new CDC study, published Thursday in the journal JAMA, suggests that this real number represents about 20% of Americans over the age of 16.
The researchers determined this estimate with a seroprevalence survey, which estimated the number of people with antibodies in their blood who indicated a past immune response to Covid.
For the survey, the CDC used blood donation specimens from the 50 states, Washington DC and Puerto Rico.
In total, about 1.4 million blood samples were studied. These samples were collected between July 2020 and May 2021.
The researchers included a higher number of samples from blood donor regions with larger ethnic and racial minority populations, and made other analytical adjustments, trying to match their final estimates with the U.S. demographic composition.
However, they acknowledged that a perfect combination was not possible and that no other differences were likely found between the blood donors included in the study and the general population.
The final estimate: as of May 2021, approximately 20% of Americans over the age of 16 had a previous covida infection.
That number jumped significantly from July 2020 (3.5%) and December 2020 (11.5%), indicating that millions of Americans were infected – and gained immunity – during the winter hike.
Combining these estimates with the number of vaccines, CDC researchers estimated that 83.3% of Americans over the age of 16 had some degree of protection against Covid in May 2021.
As of May 2021, the Midwest and South had higher Covid protection against previous infection (left map), while all parts of the country had significant protection against vaccination (right map).
Protection varies by demographic group. In May 2021, the Midwest and South had higher rates of Covid antibodies to previous infection, compared to other regions: 23.5 and 22.2 percent, respectively.
The southwest and southwest probably had higher previous infection rates in May, as these regions were most affected by the summer and winter rises.
The Northeast had the highest overall immunity (previous infection plus vaccination), although it was 87.2%. The south had the lowest: 80.2 percent.
In a similar pattern, adolescents and young adults (ages 16 to 29) had the highest rates of Covid antibodies to infection: 27% in May 2021.
But this group had the lowest overall immunity, with a rate of 76.1%. Adolescents and young adults are more likely to have mild cases of Covid than their seniors, but they are also less likely to get vaccinated.
Older people (over 65) had the highest combined immunity rate, at 92%. According to CDC data, 82 percent of U.S. seniors are completely vaccinated.
In some cases, the groups with the highest protection against previous Covid cases were also the groups with the lowest vaccination rates, which led to lower overall protection.
Black and Hispanic / Latino Americans had higher rates of antibodies coagulated by infection than other racial and ethnic groups (30% and 21.1%, respectively).
Combined immunity rates (previous infection plus vaccination) were the highest among Asian and white Americans (91% and 83.8%, respectively).
This combined immunity rate was 79.2% for black Americans and 81.5% for Hispanics / Latin Americans, reflecting lower vaccination rates in these groups.
The CDC’s blood sampling study will continue until at least December 2021 and researchers say they intend to continue publishing data.
With more than 80% of Americans potentially protected against Covid, it is easy to conclude that the country has achieved herd immunity.
After all, President Biden made the 70% vaccination rate his national goal.
The Delta variant has changed the game, though. Now, researchers say 95% or more of Americans need to be protected to stop outbreaks.
CDC researchers point out that “additional research is needed” on the connections between a previous infection and herd immunity.
“Infection-induced protection may decrease more rapidly than vaccine-induced protection,” they write.
For this reason, experts recommend that Americans be vaccinated even if they have had a previous covida infection.
However, the study indicates that we have had many more cases of Covid in the US than those that have been officially reported.
CDC researchers estimate that by July 2020, for every Covid case reported, two more could be detected after blood tests.
In May 2021, that number dropped to an additional case for each case that was officially reported.
The number may be even higher now, however, as many vaccinated people are not looking for evidence of mild colds and other symptoms that may indicate a breakthrough in Covid’s case.
