COVID Vaccination Associated with Lower Viral Load, Likelihood of Systemic Symptoms

This is an abstract. The full journal study is available to read via the link in the source information below.

Background

Data conflict on whether vaccination decreases SARS-CoV-2 viral load. The objective of this analysis was to compare baseline viral load and symptoms between vaccinated and unvaccinated adults enrolled in a randomized trial of COVID-19 treatment.

Methods

Baseline data from the first 433 sequential participants enrolling into the COVID-OUT trial were analyzed. Adults aged 30-85 with a BMI ≥25 were eligible within 3 days of a positive SARS-CoV-2 test and <7 days of symptoms. PCR viral loads were normalized to human RNase P by vaccination status, by time from vaccination, and by symptoms.

Results

Two hundred seventy-four participants with known vaccination status contributed optional nasal swabs for viral load measurement: median age, 46; median (interquartile range) BMI 31.2 (27.4-36.4). Overall, 159 (58%) were women, and 217 (80%) were white. The mean relative log10 viral load for those vaccinated <6 months from the date of enrollment was 0.11 (95% CI -0.48 to 0.71), which was significantly lower than the unvaccinated group (P=0.01). Those vaccinated ≥6 months before enrollment did not differ from the unvaccinated with respect to viral load (mean 0.99, 95% CI -0.41 to 2.40, P=0.85). The vaccinated group had fewer moderate/severe symptoms of subjective fever, chills, myalgias, nausea, and diarrhea (all P<0.05).

Conclusions

These data suggest that vaccination within 6 months of infection is associated with a lower viral load, and vaccination was associated with a lower likelihood of having systemic symptoms.

Read an interview about the study here.

The full text of this study can be accessed via the source information below.