In a recent article published on medRxiv* preprint server, researchers in the United States analyzed pneumococcal carriage in the elderly in the Greater New Haven area of the United States (USA) when implementing mitigation strategies of coronavirus disease 2019 (COVID-19).
Study: Persistence of pneumococcal carriage in community elderly despite COVID-19 mitigation measures. Image Credit: Kateryna Kon/Shutterstock
COVID-19 mitigation strategies have had a significant impact on other infectious disease incidences. Major respiratory viruses, such as respiratory syncytial virus, human metapneumovirus, and influenza, largely disappeared as pathogens in the northern hemisphere during the winter of 2020-2021. All age categories saw a substantial decline in invasive pneumococcal infections (IPI) in spring 2020. It only returned to near normal levels in spring/summer 2021.
There was a significant rate of pneumococcal transmission among children during the first year of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Yet social distancing and other COVID-19 mitigation approaches may have decreased the frequency of interactions and pneumococcal transmission from children to adults.
The rapid decline of pneumococcal disease in adults following vaccination of children with pneumococcal conjugate vaccines has clearly demonstrated that children represent an important source of pneumococcal exposure for adults. Nevertheless, the prevalence of pneumococcus in the elderly during this period is uncertain.
About the study
In the current study, researchers from Yale University and Pfizer Inc hypothesized that some of the decreases in IPD observed in adult populations may have resulted from decreased contact between adults and children during the SARS-CoV-2 pandemic. Therefore, the team assessed the pneumococcal carriage rates of people aged 60 or older who were enrolled in active longitudinal pneumococcal carriage research and living in the community in the United States in the years 2020-2021. The objectives of the study included the measurement and identification of pneumococcal carriage rates in the elderly and the assessment of familial transmission among cohabiting elderly.
From October 2020 to August 2021, the authors recruited couples residing in the Greater New Haven area who were both 60 or older and had no residents under 60 in their household. The household pair’s participation in the study was deferred for approximately four weeks if they showed signs of a respiratory infection at the time of enrollment, received a pneumococcal vaccination, or had recently taken antibiotics within the four previous weeks. No subject was excluded from the investigation based on comorbidity status.
For 10 weeks, questionnaires on social activities, interactions and medical history were collected every two weeks, along with saliva samples. Additionally, all sputum specimens were checked for SARS-CoV-2 ribonucleic acid (RNA) using the Saliva Direct non-extraction test.
After culture enrichment, the collected deoxyribonucleic acid (DNA) was screened for pneumococcal-specific sequences: lytA and piaB, using quantitative polymerase chain reaction (qPCR). Study volunteers were considered positive for pneumococcal carriage when cycle threshold (Ct) values for piaB were
The authors noted that in the current research, community-dwelling older adults remained pneumococcal-positive at rates comparable to other pre-pandemic experiments in older adults that used similar molecular techniques. This was contrary to the significant decline in IPI rates reported in adults during the first winter season of the COVID-19 pandemic, i.e. 2020-2021. Additionally, the team mentioned that the current survey was conducted when transmission mitigation techniques related to the SARS-CoV-2 pandemic were in effect.
The results of the study indicated that the scientists obtained 567 saliva samples from 95 adults aged 60 or over from one singleton and 47 household pairs. Of these samples, 7.1% were pneumococcal positive and contained either only piaB (six samples) or both lytA and piaB (34 samples), including 22/95, or 23.2%, individuals and 16 /48, or 33.3%, of households during the 10-week trial.
The study volunteers attended a few social gatherings during this time. Many participants, however, still had frequent interactions with the children. People who regularly interacted with children aged 2 to 9, i.e. preschool and school-aged children, had a higher pneumococcal carriage rate of 15.9% versus 5.4% .
According to the study results, older adults in the Greater New Haven area often had pneumococcal infections during the 10-week study period, despite SARS-CoV-2-related disruptions. Those who interacted with school-aged children notably had a higher prevalence, but this group was not the only one affected.
Researchers have found little evidence of the influence of COVID-19 pandemic mitigation efforts on pneumococcal carriage rates in older adults during the first research period of an ongoing investigation examining pneumococcal carriage rates in Greater New Haven. The study results imply that school-aged children were the most likely source of the pneumococcus that persisted in most study participants during the period of decreased social contact.
The high frequency of non-specific signal found in the commonly used lytA qPCR assay underscores the importance of focusing on multiple genetic targets for accurate and precise detection of pneumococcus in oral specimens. Further research using molecular serotyping of obtained samples will further shed light on this observation and patterns of pneumococcal transmission in households with only people over 60 years of age.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice/health-related behaviors, or treated as established information.
- Persistence of pneumococcal carriage in older people in the community despite COVID-19 mitigation measures; Anne L. Wyllie, Sidiya Mbodj, Darani A. Thammavongsa, Maikel S. Hislop, Devyn Yolda-Carr, Pari Waghela, Maura Nakahata, Anne E. Watkins, Noel J. Vega, Anna York, Orchid M. Allicock, Geisa Wilkins, Andrea Ouyang, Laura Siqueiros, Yvette Strong, Kelly Anastasio, Ronika Alexander-Parrish, Adriano Arguedas, Bradford D. Gessner, Daniel M. Weinberger. medRxiv preprint 2022, DOI: https://doi.org/10.1101/2022.06.28.22276654, https://www.medrxiv.org/content/10.1101/2022.06.28.22276654v1