Study looks at pneumococcal carriage among over 60's during COVID pandemic

In a recent article posted to the medRxiv* preprint server, researchers in the United States analyzed the pneumococcal carriage in older adults in the Greater New Haven Area, United States (US), during the implementation of coronavirus disease 2019 (COVID-19) mitigation strategies.

Study: Persistence of pneumococcal carriage among older adults in the community despite COVID-19 mitigation measures. Image Credit: Kateryna Kon / Shutterstock

Background 

The COVID-19 mitigation strategies significantly impacted other infectious disease incidences. Major respiratory viruses, such as respiratory syncytial virus, human metapneumovirus, and influenza, largely vanished as disease-causing agents in the Northern Hemisphere during the winter of 2020–21. All age categories experienced a substantial fall in invasive pneumococcal disease (IPD) in the 2020 spring. It did not reach almost normal levels again until the 2021 spring/summer.

There was a significant rate of pneumococcus transmission across children in the initial year of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Yet, social distancing and other COVID-19 mitigation approaches might have decreased the frequency of interaction and pneumococcal transmission from children to adults.

The rapid decline in adult pneumococcal illness after vaccinating children with the pneumococcal conjugate vaccines made it clear that children represent a significant source of pneumococcus exposure for adults. Nevertheless, the prevalence of pneumococcus across older adults during this time is uncertain.

About the study

In the present study, the researchers at Yale University and Pfizer Inc hypothesized that some of the decreases in IPD seen in adult populations may have resulted from diminished contact between adults and children during the SARS-CoV-2 pandemic. Therefore, the team assessed the pneumococcal carriage rates of persons aged 60 years or older who were enrolled in an active longitudinal pneumococcal carriage research and lived in the community in the US in the years 2020–21. Study objectives included measuring and identifying pneumococcal carriage rates among older adults and assessing household transmission among cohabiting older adults.

From October 2020 to August 2021, the authors recruited couples residing in the Greater New Haven Area who were both 60 years or older and without residents under 60 years in their households. The participation of the household pair in the study was postponed by around four weeks if they had signs of a respiratory infection at the time of registering, received a pneumococcal vaccination, or had recently taken antibiotics during the previous four weeks. No subjects were excluded from the investigation based on comorbidity status.

For 10 weeks, questionnaires about social activities, interactions, and health history were collected every two weeks, along with saliva samples. Additionally, all spit samples were checked for SARS-CoV-2 ribonucleic acid (RNA) utilizing the extraction-free Saliva Direct test. 

After culture enrichment, collected deoxyribonucleic acid (DNA) was examined for the pneumococcus-specific sequences: lytA, and piaB, employing quantitative polymerase chain reaction (qPCR). Study volunteers were regarded positive for pneumococcal carriage when cycle threshold (Ct)-values for piaB were <40.

Results 

The authors noted that in the current research, older individuals living in the community remained pneumococcus-positive at rates comparable with other pre-pandemic experiments of elderly persons that used similar molecular techniques. This was contrary to the significant drop in reported IPD rates among adults in the first winter season of the COVID-19 pandemic, i.e., 2020–21. Moreover, the team mentioned that the current investigation was performed when SARS-CoV-2 pandemic-related transmission mitigation techniques were in effect.

The study results indicated that the scientists procured 567 saliva samples from 95 adults aged 60 years or older from one singleton and 47 household pairs. Among these samples, 7.1% were pneumococcus-positive containing either just piaB (six samples) or both lytA and piaB (34 samples), comprising 22/95, or 23.2%, of the individuals and 16/48, or 33.3%, of the households during the 10-week long trial. 

Study volunteers attended a few social gatherings during this time. Many participants, nevertheless, still had frequent interactions with children. People who regularly interacted with two to 9-year-olds, i.e., preschool and school-aged children, had a greater rate of pneumococcus carriage, i.e., 15.9% versus 5.4%.

Conclusions 

According to the study findings, the Greater New Haven Area's older adults often had pneumococcus infections in the 10-week study period, despite SARS-CoV-2-linked disruptions. Those who interacted with school-aged children notably had a higher prevalence, but this group was not the only ones affected.

The researchers discovered little indication of the influence of the COVID-19 pandemic mitigation efforts on rates of pneumococcal carriage in older individuals in the first research period of an ongoing investigation examining rates of pneumococcal carriage in Greater New Haven. The study findings imply that school-aged children were the most likely source of the pneumococcus that persisted in most study participants during the time of decreased social contact.

The high frequency of the non-specific signal found in the commonly used lytA qPCR test highlights the significance of focusing on several gene targets for accurate and precise pneumococcus detection in oral samples. Additional research using molecular serotyping of the procured samples will shed more light on this observation and the pneumococcal transmission patterns in households with only people over 60 years.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Shanet Susan Alex

Shanet Susan Alex, a medical writer, based in Kerala, India, is a Doctor of Pharmacy graduate from Kerala University of Health Sciences. Her academic background is in clinical pharmacy and research, and she is passionate about medical writing. Shanet has published papers in the International Journal of Medical Science and Current Research (IJMSCR), the International Journal of Pharmacy (IJP), and the International Journal of Medical Science and Applied Research (IJMSAR). Apart from work, she enjoys listening to music and watching movies.