COVID vaccine protection drops by 40% due to Delta variant — even worse for Johnson & Johnson shot

OAKLAND, Calif. — Breakthrough cases of COVID-19 have been a generally rare occurrence among Americans getting one of the available vaccines. Unfortunately, a new study finds that protection is fading significantly due to newer strains of the virus — like the Delta variant. Researchers with the Public Health Institute report that the overall effectiveness of these shots has dropped by nearly 40 percent over the last year.

The news is even worse for the single-dose Johnson & Johnson vaccine. Researchers find its effectiveness against COVID infections has plummeted from 86.4 percent in March 2021 to just 13 percent as of September.

A team from PHI, the Veterans Affairs Medical Center, and the University of Texas Health Science Center monitored the health of more than 780,000 U.S. veterans who received one of the three major COVID vaccines available in the United States. Overall, protection against breakthrough cases has fallen from 87.9 percent in February 2021 to 48.1 percent in October.

The drops in effectiveness were less dramatic for the two-dose vaccines currently available. Study authors discovered that COVID protection from the PfizerBioNTech decreased from 86.9 percent to 43.3 percent over the year. Patients receiving the Moderna vaccine are faring even better, with the vaccine dropping from 89.2 percent to 58 percent effectiveness against breakthrough infections.

COVID vaccines are still keeping people from dying

Study authors started their first-of-its-kind investigation to examine if the three main vaccine types would start to weaken over time. Starting in February 2021, they were able to account for the growing dominance of the Delta variant, which researchers say is a main factor in the drop in protection.

Although the current COVID vaccines may not offer as much protection against people contracting the virus as they did earlier in 2021, the study finds they’re still keeping the vast majority of patients from dying. Researchers find that the vaccines’ protection against fatal cases of COVID is highest among people under 65, but still strong in seniors as well.

Overall, protection against death from COVID-19 among vaccinated individuals under 65 remains at 81.7 percent. Among younger people, the Pfizer vaccine displayed the best protection against fatal complications (84.3%), followed by Moderna (81.5%), and then Johnson & Johnson (73%).

For people over 65, the vaccines prevent death from COVID 71.6 percent of the time. Moderna remains the best option for seniors, preventing death in 75.5 percent of cases. Pfizer’s effectiveness dropped to 70.1 percent and the Johnson & Johnson shot fell significantly to 52.2 percent.

Researchers note that the risk of dying from COVID-19 is still greatest among unvaccinated participants, regardless of their age or pre-existing health conditions. Although some breakthrough cases can still result in death, the team finds the current vaccines are still keeping most patients from dying from the Delta variant.

Does this mean people need a COVID booster shot?

“Our study gives researchers, policy makers and others a strong basis for comparing the long-term effectiveness of COVID vaccines, and a lens for making informed decisions around primary vaccination, booster shots, and other multiple layers of protection, including masking mandates, social distancing, testing and other public health interventions to reduce chance of spread,” says lead study author Dr. Barbara Cohn of PHI in a media release.

“The CDC recommendation for boosters for all Janssen recipients over 18 is supported by our results. And, given the declines in vaccine protection and the dominance of the more infective Delta variant, we urge swift action to promote primary vaccination, boosters and to also encourage masking, social distancing and other layers of protection against infection. This is supported by our finding that breakthrough infections are not benign, but also by the strong evidence that vaccination still protects against death even for persons with breakthrough infections, compared to persons who become infected and are not vaccinated.”

The findings appear in the journal Science.

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