Protection against COVID-19 infection among vaccinated individuals declined for all vaccine types as the Delta variant surged in 2021, according to an analysis of Veterans Affairs (VA) data for nearly 800,000 veterans published November 4 by the journal Science. However, the study also found that vaccination of any type was protective against death among individuals who became infected.
Researchers from the Public Health Institute (PHI), the Veterans Affairs Medical Center in San Francisco and the University of Texas Health Science Center at Houston analyzed vaccination and infection data for 780,225 veterans. They used the VA Corporate Data Warehouse (CDW) to identify vaccination status (fully vaccinated vs. unvaccinated), vaccine type (Pfizer-BioNTech, Moderna, Janssen), and SARS CoV-2 infections during the period February 1, 2021 to August 13, 2021. The VA CDW provides discrete, individual-level data, including demographics, administrative claims-based diagnosis and procedure codes, prescriptions, anthropometric measures, and free-text data including procedure notes and pathology reports; data include all 50 states and U.S. territories.
"The VA CDW was essential to our timely analysis of breakthrough infections and deaths up until October 1, 2021, and moving forward, these data may be used as tool to comprehensively monitor vaccine effectiveness as other variants are likely to emerge," the authors wrote.
The investigators found that overall vaccine protection declined from 87.9% in February to 48.1% by October 2021. The decline was greatest for the Janssen (Johnson & Johnson) vaccine, with protection against infection declining from 86.4% in March to 13.1% in September. Declines for the Pfizer/BioNTech vaccine were from 86.9% to 43.3%, and declines for the Moderna vaccine were from 89.2% to 58%.
As COVID-19 breakthrough infections continue to emerge in some vaccine recipients and health authorities are developing policies around booster vaccinations, national data on COVID-19 vaccine breakthrough infections is inadequate but urgently needed.
While most previous studies have focused on the PfizerBioNTech or Moderna vaccines, the Science study is the first to compare protection declines across the three main vaccine types, and the first to show the comparably dramatic decline in effectiveness for the Janssen vaccine. Declines were assessed over the period from February 1, 2021 to October 1, 2021, reflecting the emergence and dominance of the Delta variant in the U.S. Patterns of breakthrough infection over time were consistent by age, despite rolling vaccine eligibility, implicating the Delta variant as the primary determinant of infection.
Importantly, vaccination of any type was protective against death among individuals who did become infected. The relative benefit of vaccination for protection against death was greater for persons aged younger than 65 years but was also very strong for persons older than 65 years.
The study showed that the risk of death from COVID infection was highest in unvaccinated veterans, regardless of age and comorbidities. While some breakthrough infections resulted in death, vaccination remained protective against death in those who became infected during the Delta surge.
For those younger than 65 years old, vaccines overall were 81.7% effective against death.
* Protection against death was greatest for the Pfizer vaccine, at 84.3%.
* Moderna was the next most effective, at 81.5%.
* Jansen was 73% effective.
For those aged 65 years and older, overall vaccine effectiveness against death was 71.6%.
* Moderna was 75.5% effective.
* Pfizer was 70.1% effective.
* Jansen was 52.2% effective.
“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,” said Dr. Barbara Cohn of PHI, the lead author of the study. “For example, 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 FDA authorized Pfizer boosters for some groups in September and Moderna and Janssen boosters in October, and the CDC has made similar recommendations, including supporting a “mix and match” approach that allows people to choose any of the three vaccine boosters regardless of which they were given initially.
Read the study: https://www.science.org/doi/10.1126/science.abm0620