Decreased vaccine efficacy associated with delta variants

San Diego (CNS)-A team of researchers at the University of California, San Diego issued a letter on Wednesday showing that the efficacy of both the Pfizer vaccine and the Modana COVID-19 vaccine has declined significantly over time. Delta variant.

Published in the New England Journal of Medicine, this letter was written by an interdisciplinary team of UCSD physicians and public health professionals. They measured the efficacy of the COVID-19 mRNA vaccine among UCSD Health healthcare professionals. Most places are fully vaccinated, especially at the time of the emergence of highly contagious Delta virus variants and at the end of the state’s Maskmandate.

The authors state that between March and June, vaccine efficacy against symptomatic infections was estimated to exceed 90%. But by July, it had dropped to about 65%.

Both Pfizer and Moderna vaccines were granted an emergency use authorization by the U.S. Food and Drug Administration last December, and UCSD Health employees will be vaccinated in the same month for employees who are obliged to face the patient directly. It started from.

“The decline in efficacy is not surprising at all,” said Francesca, a professor of clinical medicine in the Department of Infectious Diseases and Global Public Health at the University of California, San Diego School of Medicine and co-lead author, Director of Infection Prevention and Clinical Programs.・ Dr. Triani said. Epidemiology at UCSD Health.

“Clinical trial data suggest that reduced efficacy occurs months after complete vaccination, but our findings show that vaccine efficacy against mild symptomatic disease is significant in the face of delta variants. It is low, indicating that it has declined 6 to 8 months after vaccination is complete, “Torriani said.

In December, UCSD Health workers began to experience a surge in SARS-CoV-2 infection (the virus that causes COVID-19), as well as the entire population. The situation improved significantly after the hospital system began inoculating employees with the double-dose vaccine. By March, 76% of UCSD Health workers had been fully vaccinated, rising to 83% by July.

In addition to the increase in vaccination rates, from March to June, the number of workers reporting at least one sign of COVID-19 and a positive test decreased. That number dropped to less than 30 employees a month.

However, in July, with the emergence of the predominance of delta variants in San Diego and the end of the California masking mandate on June 15, cases of the highly vaccinated population began to increase again. By the end of July, 125 workers had been diagnosed. In the case of SARS-CoV-2, the proportion increased to 75%, unlike the previous month when about 20% of cases were associated with vaccinated workers, the researchers said.

In particular, cutin still provides significant protection from the consequences of serious infections such as hospitalization and death. Of the documented cases of UCSD Health employees, no hospitalization was reported in vaccinated individuals and only one was reported in unvaccinated individuals.

“Unlike what was experienced in other variants, parents of the Delta variant frequently infect infants between the ages of 5 and 11,” said Lucy, co-lead author and assistant professor of the Department of Infectious Diseases. Dr. Houghton said. He is also the director of the UCSD HealthCOVID-19 case study and contact tracing team.

“People who are not vaccinated are seven times more likely to test positive for COVID-19 than those who are fully vaccinated,” Houghton continued. “More importantly, children rarely need treatment, but unvaccinated adults are 32 times more likely to require hospitalization than fully vaccinated adults. Become.”

Vaccine efficacy was associated with the passage of time. For workers diagnosed in July, those who were fully vaccinated in January and February had a higher infection rate than those who were vaccinated in the latter half of March-May. Infection rates in unvaccinated people remain consistently higher than in any vaccinated group, but the difference in infection rates between the two groups has diminished over time.

“Dramatic changes in vaccine efficacy from June to July are likely due to a combination of factors,” said Nancy, co-author of the Department of Medicine and Herbert-Wertheim, a professor of epidemiology at the School of Public Health and Human Longevity Sciences.・ Dr. Binkin said. .. “This is the emergence of delta variants and a decrease in immunity over time, exacerbated by the end of a wide range of masking requirements and the consequent increased risk of exposure throughout the community.”

Dr. Shira Abeles, an assistant professor in the Department of Infectious Diseases who led the COVID-19 vaccination effort at UCSD Health, said the findings show vaccination rates in addition to indoor masking and intensive testing strategies. Continued efforts to enhance.

“Similar findings have been reported in other situations in the United States and internationally and are likely to require booster immunization,” Abelles said.