Additional Studies Point to Waning Immunity from Vaccines

 

More studies into vaccinated populations show that although antibody responses drop months after vaccination against COVID-19, they still dramatically protect against severe disease and hospitalization. Studies are also continuing on the value and efficacy of booster shots, particularly against the Delta variant. Read on for more information.

More Studies Suggest COVID-19 Vaccine Immunity Wanes with Time

The U.S. Centers for Disease Control and Prevention (CDC) reported two new studies that describe how immunity to COVID-19 from vaccines decreases in the face of the spread of the Delta variant. One was in frontline health care staffers. The study suggested the effectiveness of the vaccines dropped by almost 30% since the Delta variant rose to prominence in the U.S. However, it also showed that the vaccines were 80% effective in preventing infection.

From December 14, 2020, to April 10, 2021, results from the HEROES-RECOVER Cohorts demonstrated that the mRNA vaccines, Moderna and Pfizer–BioNTech, were about 90% effective in preventing symptomatic and asymptomatic COVID-19 infection in real-world conditions. The new data updated it and included all available U.S. vaccines, meaning it added the Johnson & Johnson one-shot vaccine to the mix through August 14, 2021. Among 4,217 participants, 3,483 were vaccinated, with 2,278 receiving the Pfizer-BioNTech vaccine, 1,138 receiving the Moderna, and 67 receiving the J&J.

The study authors stated, “The VE (vaccine effectiveness) point estimates declined from 91% before predominance of the SARS-CoV-2 Delta variant to 66% since the SARS-CoV-2 Delta variant became predominant at the HEROES-RECOVER cohort study sites; however, this trend should be interpreted with caution because VE might also be declining as time since vaccination increases and because of poor precision in estimates due to limited number of weeks of observation and few infections among participants.”

The second study was in 43,000 residents of Los Angeles 16 years of age and older. From May to July, it found that 25% of new infections were in fully vaccinated people, and 71% were in unvaccinated individuals. It also showed that the hospitalization rate was significantly lower for the fully vaccinated group. Overall, 10,895 people were fully vaccinated, 1,431 were partially vaccinated, and 30,801 were unvaccinated. On July 25, infection rates in unvaccinated people were 4.9 times higher than fully vaccinated people, and hospitalizations were 29.2 times higher than in fully vaccinated people.

The authors concluded, “These data indicate that authorized vaccines protect against SARS-CoV-2 infection and severe COVID-19, even with increased community transmission of the newly predominant Delta variant.”

J&J’s Booster Vaccine Increases Antibody Response by a Factor of 9

Johnson & Johnson announced data from a study of a booster dose of its one-shot COVID-19 vaccine. In July, the company reported interim Phase I/IIa data, indicating the antibody responses were strong and stable through eight months after immunization. But then studied the booster, and new interim data demonstrated a rapid and robust increase in spike-binding antibodies and a nine-fold higher antibody level 28 days after the initial single dose. They also reported significant increases in binding antibody responses in people ages 18 to 55 and in people 65 years or older who received a lower booster dose.

“We have established that a single shot of our COVID-19 vaccine generates strong and robust immune responses that are durable and persistent through eight months,” said Mathai Mammen, Global Head, Janssen Research & Development, J&J. “With these new data, we also see that a booster dose of the Johnson & Johnson COVID-19 vaccine further increases antibody responses among study participants who had previously received our vaccine. We look forward to discussing with public health officials a potential strategy for our Johnson & Johnson COVID-19 vaccine, boosting eight months or longer after the primary single-dose vaccination.”