Among patients with cystic fibrosis (CF), 11% had positive SARS‐CoV‐2 antibodies consistent with previous infection, and roughly a third of these reported no symptoms, according to study findings published in Pediatric Pulmonology.
Researchers conducted a study of a children with CF to identify SARS‐CoV‐2 seroprevalence and symptoms as well as antibody responses post infection or vaccine. The study was conducted at a large US‐based pediatric center.
Children and adolescents with CF from July 20, 2020, to February 28, 2021, were eligible. A total of 125 children were enrolled (median age,12 years [interquartile range, 7-17]; 51% male). Participants were asked about their previous SARS‐CoV‐2 exposures as well as findings from any prior SARS‐CoV‐2 test, symptoms that occurred between February 1, 2020, and study enrollment, and any treatment interventions. Participants were sent weekly follow‐up surveys for 56 weeks. Follow‐up serology testing was conducted at 6 and 11 months (±2 months) after enrollment, with antibody testing samples collected from July 2020 to March 2022.
Of the cohort, 14 (11%) patients with CF had positive SARS‐CoV‐2 antibodies consistent with previous infection, with 6 seropositive on enrollment, 5 seroconverted between enrollment and 6 months, and 3 who developed SARS‐CoV‐2 antibodies by 11 months.
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[T]he risk for SARS‐CoV‐2 exposure and infection in patients with CF was similar to that of the general population.
In the seropositive group, a higher proportion of patients identified as Hispanic (29% vs 8% of the seronegative group, P =.04). In addition, 71% of participants who seroconverted had a pulmonary exacerbation that required oral antibiotics in the year before enrollment vs 41% of the seronegative group (P =.04).
A multivariable regression model analyzed how seroconversion rates were affected by age, race, oral antibiotic use within the previous 12 months for a pulmonary exacerbation, methicillin‐resistant Staphylococcus aureus colonization, and use of azithromycin on seroconversion. The model found that only use of oral antibiotics for a pulmonary exacerbation had a statistically significant association with SARS‐CoV‐2 seroconversion (P =.046).
The estimated seroprevalence rate of SARS‐CoV‐2 over time was 6.2% (95% CI, 3.0-12.5) by February 9, 2021, 14.8% (95% CI, 8.4-25.4) by September 30, 2021, and 29.0% (95% CI, 11.0-63.6) by December 20, 2021.
Of the 11 participants with positive antibodies for SARS‐CoV‐2 who completed at least 1 symptom survey, 5 participants in the seropositive group reported being asymptomatic during the period when they developed SARS‐CoV‐2 antibodies (35.7% of all seropositive patients, 45.4% of those completing symptom surveys). In addition, 6 participants were symptomatic (with cough, rhinorrhea, and sore throat the most common symptoms; 42.8% of all seropositive patients, 54.5% of those completing surveys).
The participants completed an average of 66% of weekly surveys. A higher proportion of SARS‐CoV‐2-positive participants reported SARS‐CoV‐2 exposure compared with the SARS‐CoV‐2 seronegative group from February 1, 2020, to enrollment (36% vs 11%) and in the 56 weeks after enrollment (46% vs 23%).
Spike protein receptor binding domain immunoglobulin G (IgG) levels were significantly higher in participants who were vaccinated without previous evidence of infection compared with unvaccinated participants who had SARS‐CoV‐2 infection in a comparison of the first spike protein IgG level after vaccination or infection (geometric mean 1411 BAU/mL vs 47, P <.001).
Limitations include the single pediatric center design and limited sample size. Also, a majority of participants completed the study before the substantial increase in seropositivity associated with the omicron B.1.1.529 variant beginning in December 2021, and cellular immunity was not assessed.
“We estimated the seroprevalence in children and adolescents with CF to closely follow that of the general population over time,” stated the study authors. “This implies that the risk for SARS‐CoV‐2 exposure and infection in patients with CF was similar to that of the general population.”
