COVID-19 breakthrough infections that occur after a person is vaccinated are very rare, but those with weakened immune systems are three times more likely to have them and have more serious illnesses, according to a real-world study in the United States of approximately 1.3 million people.
Researchers at Pfizer conducted a previous study published in the Journal of Medical Economics that examined the medical records of 1,277,747 patients aged 16 and over who received two doses of the Pfizer / BioNTech COVID-19 vaccine between December 10, 2020 and July 2020. Later in the study period, the Delta (B1617.2) variety appeared in the United States.
A severe tumor (32.0 percent), kidney disease (19.5 percent), and rheumatological / inflammatory (16.7 percent) disorders were the most common causes of immunocompromised patients, accounting for 17.7 percent of the total population. The mean patient age of this cohort was 58 years, 48.3 percent aged 50 to 64 years, and 23.0 percent aged 65 and over; 56.3 percent were women and 74.5 percent had health insurance.
More than two-thirds (62.5 percent) of this group had at least one underlying condition that put them at risk for severe COVID-19, compared to 19.3 percent who were not immunocompromised. Obesity (9.4 percent), type 2 diabetes (9.2 percent), smoking (5.4 percent), and cancer (5.2 percent) were the most common of these diseases.
53.1 percent of patients with healthy immune systems were women and 80.2 percent had commercial health insurance; The average age was 45 years, 33.3 percent aged 50 to 64 years and 9.3 percent aged 65 years or older.
More than 38 percent of people with weakened immune systems became infected, 60 percent were hospitalized and died in both cases, although only 978 (0.08 percent) of the 1,176,907 people who received the second dose of the COVID-19 vaccine had a landmark infection the week before.
Of all the vaccinated patients, 97.1 percent of successful patients went to the doctor, and 12.7 percent needed hospitalization, while 59.7 percent had a disability. Breakthrough infections were three times more common in immunocompromised vaccines (0.18 percent) than in immunosuppressive vaccines (0.06 percent), despite the very low risk between the two groups.
The main results of the study
Breakthrough infections were most common among organ transplant recipients. Patients with several immunocompromising (IC) conditions, antimetabolite cancer drugs, primary immunodeficiency, or blood cancer have shown higher success rates than uncompromised immune systems.
Patients 65 years of age or older were more prone to infection than their younger counterparts.
“Although some groundbreaking infections of the COVID-19 vaccine are expected to occur in people who have been fully vaccinated against COVID-19, the results of this study show that they are rare and that those without IC status are less likely to be hospitalized or die,” the authors wrote. “However, further research is needed to continue monitoring groundbreaking infection rates among the general population, especially with reduced protection duration and the emergence of SARS-CoV-2 variants.”
According to a press release from the Taylor & Francis Group, the results justify the use of booster COVID-19 vaccine doses, according to the study’s lead author, Manuela de Fusco, MS, director of Pfizer’s Health Economics and Outcomes research.
“Several countries are currently experiencing a resurgence of SARS-CoV-2 infection despite the introduction of comprehensive immunization programs,” he said. “While the COVID-19 mRNA vaccines help protect people from becoming infected and seriously ill, the risk of groundbreaking infections in fully vaccinated individuals is not completely eliminated.”
According to de Fusco, the limitations of the study include coding accuracy and data representation after the study period, although it used a larger dataset that had been used in previous U.S. studies.
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