Study looks at pneumococcal carriage among people over 60 during COVID pandemic

In a recent article posted on the medRxiv* preprint server, researchers in the United States analyzed pneumococcal carrier status in older adults in the Greater New Haven Area, United States (US), while implementing strategies for the containment of the 2019 coronavirus disease (COVID-19).

Study: Persistent pneumococcal carriage in older adults in the community despite COVID-19 mitigation† Image Credit: Kateryna Kon/Shutterstock

Background

The COVID-19 mitigation strategies had a significant impact on other infectious disease incidents. 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 groups saw a significant decline in invasive pneumococcal disease (IPD) in the spring of 2020. It did not return to near normal levels until Spring/Summer 2021.

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

The rapid reduction of pneumococcal disease in adults after vaccination of children with the pneumococcal conjugate vaccines indicated that children are an important source of pneumococcal exposure for adults. Nevertheless, the prevalence of pneumococci in older adults during this period is uncertain.

About the study

In the current study, the researchers from Yale University and Pfizer Inc hypothesized that some of the declines in IPD seen in adult populations may be due to reduced adult-child contact during the SARS-CoV-2 pandemic. Therefore, the team assessed the pneumococcal carriage rates of individuals 60 years of age or older who participated in an active longitudinal study of pneumococcal carriage and lived in the community in the US during the years 2020-21. The research aims included measuring and identifying pneumococcal carriage in older adults and assessing household transmission among cohabiting older adults.

From October 2020 to August 2021, the authors recruited couples living in the Greater New Haven Area who were both age 60 and older and had no residents under age 60 in their household. The household couple’s participation in the study was delayed by approximately four weeks if they had signs of a respiratory infection at the time of registration, had received a pneumococcal vaccination, or had recently taken antibiotics in the previous four weeks. No subjects were excluded from the study based on comorbidity.

Questionnaires on social activities, interactions, and health history were collected every two weeks for 10 weeks, along with saliva samples. In addition, all spit samples were checked for SARS-CoV-2 ribonucleic acid (RNA) using the extraction-free Saliva Direct test.

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

Results

The authors noted that in the current study, elderly individuals living in the community remained pneumococcal positive at rates comparable to other pre-pandemic experiments of elderly people using similar molecular techniques. This was in contrast to the significant decline in reported adult IPD rates in the first winter season of the COVID-19 pandemic, i.e. 2020-21. In addition, the team mentioned that the current study was conducted when SARS-CoV-2 pandemic-related transmission control techniques were in effect.

The study results indicated that the scientists obtained 567 saliva samples from 95 loner adults aged 60 or older and 47 household couples. Of these samples, 7.1% were pneumococcal positive with either piaB alone (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 households during the 10-week trial.

Study volunteers attended a few social gatherings during this time. Nevertheless, many participants still had regular contact with children. People who had regular contact with children aged two to nine, ie children of pre-school and school age, had a higher risk of pneumococcal carriage, namely 15.9% versus 5.4%.

conclusions

According to the study findings, the older adults of the Greater New Haven Area often had pneumococcal infections in the 10-week study period, despite SARS-CoV-2-related disturbances. Those who interacted with school-aged children, in particular, had a higher prevalence, but this group was not the only one affected.

The researchers found in the first study period of an ongoing study of pneumococcal carriage in Greater New Haven, little evidence of the impact of efforts to reduce the COVID-19 pandemic on pneumococcal carriage rates in older individuals. . The study results imply that school-aged children were the most likely source of the pneumococcal disease that persisted over the time of reduced social contact in most study participants.

The high frequency of the non-specific signal found in the widely used lytA qPCR assay highlights the importance of focusing on different gene targets for accurate and accurate detection of pneumococci in oral samples. Additional research using molecular serotyping of the obtained samples will shed more light on this observation and the pneumococcal transmission patterns in households with only people over 60 years of age.

*Important announcement

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