Scientists have discovered that Covid-19 “pandemic babies” appear to have developed a “protection” against allergies that is unique to them, saying lockdown restrictions allowed them to develop more beneficial microbes in their gut that are acquired post-birth from their mothers.
Social distancing rules, they added, seemed to have a significant difference in the gut ecosystem of these infants, compared with those born pre-pandemic, which could help protect them against developing allergies.
Samples of faeces from 351 babies born during the first three months of the pandemic were compared with a group born pre-pandemic. The samples were collected at six months, 12 months and 24-months-old.
Allergy tests were then performed at one and two-years-old. Questionnaires were also issued to parents to understand diet, home environment and health.
The results found that only around 5% of the pandemic babies had developed an allergy to food by age one, while 22.8% in the pre-Covid group had.
They believe this could be down to lower rates of infection and illness, leading to less antibiotic use – by age one, 17% of lockdown babies had required antibiotics, compared with 80% of those pre-pandemic. In addition, the increased duration of breastfeeding is thought to have had an impact.
Professor Jonathan Hourihane, joint senior study author and consultant paediatrician at Children’s Health Ireland Temple Street, told Indy100: “This study offers a new perspective on the impact of social isolation in early life on the gut microbiome.
“Notably, the lower allergy rates among newborns during lockdown could highlight the impact of lifestyle and environmental factors, such as frequent antibiotic use, on the rise of allergic diseases.
“We hope to re-examine these children when they are five-years-old to see if there are longer-term impacts of these interesting changes in early gut microbiome.”
The research was published in the journal Allergy.
Study details
Association between gut microbiota development and allergy in infants born during pandemic-related social distancing restrictions
Katri Korpela, Sadhbh Hurley, Sinead Ahearn Ford, Ruth Franklin, Susan Byrne, Nonhlanhla Lunjani, Brian Forde, Ujjwal Neogi, Carina Venter.
Published in Allergy on 29 February 2024
Abstract
Background
Several hypotheses link reduced microbial exposure to increased prevalence of allergies. Here we capitalise on the opportunity to study a cohort of infants (CORAL), raised during Covid-19 associated social distancing measures, to identify the environmental exposures and dietary factors that contribute to early life microbiota development and to examine their associations with allergic outcomes.
Methods
Faecal samples were sequenced from infants at 6 (n = 351) and repeated at 12 (n = 343) months, using 16S sequencing. Published 16S data from pre-pandemic cohorts were included for microbiota comparisons. Online questionnaires collected epidemiological information on home environment, healthcare utilization, infant health, allergic diseases, and diet. Skin prick testing (SPT) was performed at 12 (n = 343) and 24 (n = 320) months of age, accompanied by atopic dermatitis and food allergy assessments.
Results
The relative abundance of bifidobacteria was higher, while environmentally transmitted bacteria such as Clostridia was lower in CORAL infants compared to previous cohorts. The abundance of multiple Clostridia taxa correlated with a microbial exposure index. Plant based foods during weaning positively impacted microbiota development. Bifidobacteria levels at 6 months of age, and relative abundance of butyrate producers at 12 months of age, were negatively associated with AD and SPT positivity. The prevalence of allergen sensitisation, food allergy, and AD did not increase over pre-pandemic levels.
Conclusions
Environmental exposures and dietary components significantly impact microbiota community assembly. Our results also suggest that vertically transmitted bacteria and appropriate dietary supports may be more important than exposure to environmental microbes alone for protection against allergic diseases in infancy.
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