Vaccines still work: CDC studies show COVID breakthrough infection rate remains low despite Delta variant

Breakthrough cases of COVID-19 among vaccinated people remain rare (and are generally less serious when they do occur), despite the surge of the hypercontagious Delta variant. The attention that these cases get in the media, however, is significant.

Reports of COVID-19 cases among vaccinated members of the Chicago Cubs’ front office, three U.S. senators and a cluster of people in Provincetown, Mass., have put a spotlight on breakthrough cases and raised questions about the continued effectiveness of vaccines in the face of the Delta threat.

But vaccines continue to offer strong protection against the most severe forms of the disease.

“We may have been giving a message that sounds like the vaccines aren't working very well, which to me can scare the vaccinated and actually doesn't make the unvaccinated think they should get a vaccine,” Dr. Monica Gandhi, an infectious disease specialist and professor of medicine at the University of California, San Francisco, told Yahoo News.

“[Vaccinated] people are really very protected from severe disease. … I think we need to be way more positive,” she added.

See also: 'Is the outdoors still safe? Concerns about Delta prompt new guidelines'

On Friday, the Centers for Disease Control and Prevention published three studies that highlight the continued effectiveness of all three approved vaccines in the U.S.: those produced by Pfizer, Moderna and Johnson & Johnson.

According to one of the studies, among approximately 600,000 COVID-19 cases recorded across 13 U.S. jurisdictions, there was some increase in breakthrough cases since the Delta variant gained dominance in the U.S. But that number remains a very small percentage of the total number of vaccinated people in the study.

During the time frame when the data was collected — between April 4 and July 17 — only 46,312 (8 percent) cases were reported among fully vaccinated people, compared with 569,142 (92 percent) of COVID-19 cases among people who were not fully vaccinated. Hospitalized or fatal COVID-19 vaccine breakthrough cases also remained uncommon.

Of the total cases in the study, only 2,976 (a similar 8 percent) of hospitalizations, and 616 (9 percent) of deaths were reported among fully vaccinated people, compared with 34,972 (92 percent) of hospitalizations and 6,132 (91 percent) of deaths among people who were not fully vaccinated.

The studies confirm that the vaccines continue to do what they are supposed to: protect from severe disease and death. According to the CDC report, unvaccinated people were five times as likely to be infected, 10 times as likely to be hospitalized and 10 times more likely to die than fully vaccinated people.

“The bottom line is this,” said CDC Director Rochelle Walensky at a Friday press conference. “Vaccination works and will protect us from the severe complications of COVID-19.”

Recently released data on COVID breakthrough infections in New York also aligns with the CDC report findings. According to the New York State Department of Health, of the nearly 1.3 million COVID infections recorded in the state between Jan. 1 and Sept. 5, 2021, just 58,030, or 4 percent, involved breakthrough infections. On the other hand, unvaccinated people were 21 times as likely to be infected or hospitalized statewide.

Breakthrough cases are to be expected, as no vaccine is “100 percent effective at preventing illness,” according to the CDC. In addition, not everyone is able to build a robust immune response to the shots. This is particularly true for those who are immunocompromised, have underlying health conditions or are age 65 or older.

As of Aug. 30, people 65 and older represented about 70 percent of the breakthrough cases reported to the CDC that resulted in hospitalization.This demographic also represented about 87 percent of the breakthrough cases resulting in death.

Gandhi told Yahoo News that it is important to know more specifics about these severe cases among vaccinated people in order to better protect them.

“What a lot of people are asking the CDC to do is to please tell us all the characteristics of those severe breakthroughs,” she said. “Those are likely the people who are going to need a third shot.”

The good news for most healthy vaccinated people is that the vaccines are continuing to protect them from severe illness, and even a breakthrough infection will result in mild symptoms or none at all.

Experts urge vaccinated Americans to nevertheless continue following the public health guidance designed to curb the spread of the virus.

The CDC reported in July that vaccinated people who caught the Delta variant could carry roughly the same viral load in their noses and throats as unvaccinated people. Based on this evidence, the agency made a revision to its masking guidelines, recommending indoor mask use — even for those who are vaccinated — in areas of the country with substantial or high transmission.

But Gandhi said that more recent studies seem less alarming because vaccinated people will clear the virus more quickly, reducing the length of time that they are infectious.

“That makes sense, because your immune system is going to fight that virus and bring down the viral load,” she said.

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