Breakthrough Infections

This preprint retrospective analysis identifies risk factors associated with breakthrough infections using electronic health record from Columbia University Irving Medical Center/New York Presbyterian.  The researchers aimed to address the following:

1. What risk factors are associated with breakthrough infections?
2. How effective are vaccines in reducing the rate of infection?
3. How effective are vaccines in reducing the risk of severe outcomes?

Data used were from January 18, 2021 until September 21, 2021.  There were three cohorts: “vax” cohort (vax positive and vax negative), “pre-vax” cohort (pre-vax positive and pre-vax negative), and “un-vax” cohort (un-vax positive and un-vax negative).  The groups are explained as:

• Vax positive group: positive PCR test after full vaccination with no prior COVID infection  (N = 198).
• Vax negative group: negative PCR test after full vaccination with no prior COVID infection (N = 14,164).
• Pre-vax positive group: positive PCR test before the vaccination period (N = 6,462).
• Pre-vax negative group: negative PCR test and no prior COVID infection (N = 55,580).
• Un-vax positive group: positive PCR test before first vaccine dose, if administered (N = 3,902).
• Un-vax negative group: negative PCR test before first vaccine dose, if administered (N = 33,850).

Data extracted included sociodemographic characteristics, brand of vaccine administered, dates administered, total number of visits, and underlying conditions.  Poisson regression analysis was used to identify relationships between breakthrough infections and risk factors; logistic regression analysis was used to identify relationships between vaccine administration and infection rate.  For the “Vax positive” (breakthrough cohort), the average age was 58.5 (SD: 20.3). 156 (78.8%) received Pfizer/BNT162b2, while 42 (21.2%) received Moderna/mRNA-1273. When examining high-risk individuals, 65 (45.5%) had underlying immunocompromised conditions and 120 (60.6%) of the patients with breakthrough infections were hospitalized. In general, PCR positive individuals had a higher number of prior visits and observational days compared to unvaccinated individuals. The overall estimated breakthrough infection rate was 0.16 (95% CI: 0.14 – 0.18). Underlying compromised immune system was significantly associated with a high incident rate of infection among vaccinated (IRR = 1.48; 95% CI: 1.09-2.00). Those with primary immunodeficiency, history of organ transplant, active tumor, and use of immunosuppressant medications were at the highest risk. When comparing the “Vax” cohort with the “Pre-Vax” cohort, the risk of COVID-19 infection in vaccinated individuals was significantly lower (OR = 0.12, 95% CI: 0.10– 0.13). There was also a similar reduction in the incidence rate (RR = 0.42, 95% CI: 0.36-0.49) when comparing the “Vax” cohort with the “Un-Vax” cohort.  Furthermore, when comparing the “Pre-Vax” positive cohort to the “Vax” positive cohort, there was a significant reduction in death (HR = 0.20, 95% CI: 0.08-0.49). When comparing the vaccinated and unvaccinated cohorts, similar results were seen (HR = 0.41; 95% CI: 0.17-1) and hospitalization (HR = 0.72; 95% CI: 0.6-0.87).  Although there may be waning vaccine efficacy over time as noted in the study, the overall findings further emphasize the importance of vaccination and their effectiveness in preventing severe illness and hospitalization.

Diet and COVID-19 Infection

The foods we consume on a daily basis have a significant impact on gut health which is important in the proper functioning and response of the immune system.  An unhealthy lifestyle and poor metabolic health are both associated with a number of chronic health conditions and are also associated with increased risk and severity of COVID-19 infection.  This article from the British Medical Journal aims to further investigate the association between diet quality and severity of COVID-19 infection.  Data were used from the COVID-19 Symptom Study which is a smartphone-based study conducted both in the US and UK.  Participants were followed from March 24, 2020 until December 2, 2020.  Those who reported any infection-related symptoms prior to the beginning of the follow-up or those who tested positive prior to the beginning of follow-up were excluded from the study.  Sociodemographic factors along with data related to food consumption were collected.  Diet information was collected using a short-term food frequency questionnaire and the Plant-Based Diet Score was used to assess diet quality.  Prospective analysis was conducted using Cox regression.  After exclusions, there were 592,571 participants in the study analysis.  Individuals in the highest quartile of the diet score (reflecting a healthier diet of plant-based foods) had the following characteristics: older, female, healthcare workers, of lower BMI, engage in physical activities ≥5 days/week and less likely to reside in areas with higher socioeconomic deprivation.  During the follow-up period, 31,815 COVID-19 cases were documented.  Those with a high diet quality had a lower risk of COVID-19 (HR 0.91; 95% CI 0.88 to 0.94) and severe COVID-19 (HR 0.59; 95% CI 0.47 to 0.74) compared to those in the lowest quartile (reflecting an unhealthy diet).  The association between poor diet and increased socioeconomic deprivation with infection risk was much greater than risks of other factors combined.

Furthermore, this article examines dietary habits of healthcare workers who, given their occupation, have substantial exposure to COVID-19.  The study included 568 cases and 2316 controls.  Of the 568 cases, 138 had COVID-19 infection that was moderate-severe whereas the remainder had mild infection.  Overall, those who reported following ‘plant-based diets’ and ‘plant-based or pescatarian diets’ had 73% (OR 0.27, 95% CI 0.10 to 0.81) and 59% (OR 0.41, 95% CI 0.17 to 0.99) lower odds of developing moderate-to-severe infection respectively, compared with those who did not follow a plant-based or pescatarian diet.  These findings emphasize that a healthy diet rich in nutrient dense foods is an essential component of overall health and research shows that this can reduce severity of COVID infection. It is important to note that the data above were collected prior to vaccine administration.  Since the onset of the pandemic, there has been very little emphasis in public health messaging regarding nutritional recommendations and the importance of a healthy diet and lifestyle but evidence shows that a plant-based diet and specific foods can either strengthen immune system function and response or damage it.  In order to have a continued effective response to the pandemic, vaccinations along with diet and nutrition need to be emphasized.