In a recent article on the medRxiv* Preprint servers analyzed pneumococcal transport in the United States in older adults in the New Haven metropolitan area, United States (USA) during the implementation of strategies to contain the spread of the Coronavirus 2019 (COVID-19) disease.
Study: Persistence of Pneumococcal Sheltering in Community Older Adults Despite COVID-19 Mitigation Measures. Credit: Kateryna Kon/Shutterstock
COVID-19 containment strategies significantly impacted other infectious disease cases. Major respiratory viruses such as respiratory syncytial virus, human metapneumovirus and influenza largely disappeared as pathogens in the northern hemisphere during the winter of 2020/21. All age categories saw significant decreases in invasive pneumococcal disease (IPD) in spring 2020. Only in spring/summer 2021 did it return to almost normal values.
The first year of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic saw a significant rate of pneumococcal transmission to children. However, social distancing and other approaches to mitigating COVID-19 may have reduced the frequency of interactions and transmission of pneumococcus from children to adults.
The rapid regression of pneumococcal disease in adults following vaccination of children with pneumococcal conjugate vaccines highlighted that children are an important source of adult pneumococcal exposure. However, the prevalence of pneumococci in older adults during this time is uncertain.
About the study
In the present study, researchers from Yale University and Pfizer Inc hypothesized that some of the decreases in IPD seen in adults may be due to reduced contact between adults and children during the SARS-CoV-2 pandemic. Therefore, the team assessed the pneumococcal carrier rates of people aged 60 years or older who participated in active longitudinal pneumococcal carrier research and lived in the US community in 2020-21. Study objectives included measuring and identifying pneumococcal carrier rates in older adults and assessing household transmission in cohabiting older adults.
From October 2020 through August 2021, the authors recruited couples residing in the New Haven metro area who were both age 60 or older and had no residents under the age of 60 in their households. The household couple’s participation in the study was delayed by approximately four weeks if they had signs of respiratory infection at the time of enrollment, were receiving pneumococcal vaccination, or had recently taken antibiotics in the previous four weeks. No subjects were excluded from the study based on comorbidity status.
Questionnaires on social activities, interactions, and health history were collected along with saliva samples every two weeks for 10 weeks. In addition, all spit samples were tested for SARS-CoV-2 ribonucleic acid (RNA) using the extraction-free Saliva Direct test.
After culture enrichment, the collected deoxyribonucleic acid (DNA) was analyzed for the pneumococcus-specific sequences: lytA and piaB, using quantitative polymerase chain reaction (qPCR). Study volunteers were considered positive for pneumococcal carriers if cycle thresholds (Ct) for piaB were < 40.
The authors noted that in the current research, older people living in the community remained pneumococcal positive at rates comparable to other prepandemic experiments in older people using similar molecular techniques. This was in contrast to the significant decrease in reported rates of IPD in adults during the first winter season of the COVID-19 pandemic, i.e. 2020–21. Additionally, the team mentioned that the current investigation was conducted when techniques to mitigate transmission related to the SARS-CoV-2 pandemic were in effect.
The study results showed that the scientists obtained 567 saliva samples from 95 adults aged 60 years and older from a singleton and 47 household pairs. Among these samples, 7.1% were pneumococcal positive and contained either only piaB (six samples) or both lytA and piaB (34 samples), representing 22/95 or 23.2% of subjects and 16/48 or 33.3 % of people were households during the 10-week trial.
Study volunteers attended some social gatherings during this time. However, many participants had frequent interactions with children. People who regularly interacted with two to nine year olds, ie preschool and school age children, had a higher rate of pneumococcal carriers, ie 15.9% versus 5.4%.
According to the study results, despite SARS-CoV-2-related disorders, the older adults of the Greater New Haven Area had common pneumococcal infections during the 10-week study period. Those who interacted with school-age children had a significantly higher prevalence, but this group was not the only one affected.
Researchers found little evidence of the impact of efforts to contain the COVID-19 pandemic on pneumococcal carrier rates in the elderly during the first research period of an ongoing investigation examining pneumococcal carrier rates in the New Haven area. The study results suggest that school-age children were the most likely source of pneumococci, which persisted in most study participants during periods of reduced social contact.
The high frequency of the non-specific signal found in the commonly used lytA qPCR test underscores the importance of focusing on multiple gene targets for accurate and precise pneumococcal detection in oral specimens. Further investigations with molecular serotyping of the obtained samples will shed more light on this observation and the transmission patterns of pneumococci in households with only persons over 60 years of age.
medRxiv publishes preliminary scientific reports that have not been peer-reviewed and therefore should not be considered conclusive, guide clinical practice/health behavior or treated as established information.
- Persistence of pneumococcal carriers among older adults in the community despite COVID-19 mitigation efforts; 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