Bordetella pertussis infection following relaxation of COVID-19 non-pharmaceutical interventions in 2021–2023 in Vancouver metropolitan area, British Columbia, Canada

• Published in: Vaccine Vol. 42; no. 22; p. 126004
• Main Authors: Reicherz, Frederic, Li, Sirui, Watts, Allison A., Goldfarb, David M., Lavoie, Pascal M., Abu-Raya, Bahaa
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 17.09.2024; Elsevier Limited
• Subjects: Adult; Allergy and Immunology; Antibodies, Bacterial - blood; blood; Bordetella pertussis; Bordetella pertussis - immunology; British Columbia; British Columbia - epidemiology; confidence interval; Coronaviruses; COVID-19; COVID-19 - epidemiology; COVID-19 - immunology; COVID-19 - prevention & control; COVID-19 infection; COVID-19 vaccines; Criteria; Diphtheria; Disease transmission; Female; Humans; Immunoglobulin G; Immunoglobulin G - blood; Infections; Male; Metropolitan areas; Middle Aged; Pandemics; Personal protective equipment; Pertussis; Pertussis toxin; Pertussis Toxin - immunology; Pharmaceuticals; Population studies; Samples; SARS-CoV-2 - immunology; Sensitivity analysis; Seroconversion; Serology; Statistical analysis; Tetanus; Toxins; Vaccination; vaccines; Viral diseases; Whooping cough; Whooping Cough - immunology; Whooping Cough - prevention & control; British Columbia; British Columbia Canada; Canada; Germany
• ISSN: 0264-410X; 1873-2518; 1873-2518
• DOI: 10.1016/j.vaccine.2024.05.052

We recently reported a near disappearance of B. pertussis and a decline in anti-B. pertussis antibodies during the peak implementation of Coronavirus disease 2019 (COVID-19) non-pharmaceutical interventions (NPI) in 2021 in British Columbia (BC), Canada. During 2021–2023, incidence of reported B. pertussis cases remained low in BC at < 1/100,000 population. This study determined how serological evidence of B. pertussis changed after the gradual relaxation of NPI between 2021–2023. Randomly selected blood samples from school staff 25–51 years old (n = 65) were collected yearly between 2021–2023 in the Vancouver metropolitan area, BC, Canada, and tested for anti-pertussis toxin (PT) IgG levels. Serological evidence of B. pertussis infection (thereafter “seroconversion”) was defined as a quantifiable anti-PT IgG levels in subjects with anti-PT IgG levels below lower limit of quantification in the preceding year or a > 4-fold increase in anti-PT IgG levels between two subsequent years. Samples were also tested for anti-diphtheria toxoid (DT) IgG, and similar seroconversion criteria were applied to exclude seroconversion due to vaccination with tetanus-diphtheria-acellular-pertussis (Tdap). Three subjects met seroconversion criteria for anti-PT IgG between 2021 and 2022 and 9 between 2022 and 2023, yielding a seroconversion rate of 4.6 /100 person-years and 14.9/100 person-years, P = 0.127, respectively. None of the subjects met the criteria for vaccination with Tdap. The geometric mean concentration of anti-PT IgG showed a statistically significant decrease in 2022 compared with 2021, 4.8 IU/mL IU/ml (95 % confidence interval [CI], 3.8–5.9) vs. 6.4 IU/ml (95 % CI, 4.9–8.2; p = 0.001), followed by a statistically significant increase in 2023 compared with 2022 6.5 IU/ml (95 % CI, 4.9–8.5) vs. 4.8 IU/ml (95 % CI, 3.8–5.9; p = 0.0006), respectively. Serological evidence of B. pertussis increased between 2022 and 2023 despite low reported cases, which suggests that B. pertussis circulation resumed after relaxing of COVID-19 NPI.