Associations between SARS-CoV-2 Infection or COVID-19 Vaccination and Human Milk Composition: A Multi-Omics Approach (preprint)

The risk of contracting SARS-CoV-2 via human milk-feeding is virtually non-existent. Adverse effects of COVID-19 vaccination for lactating individuals are not different from the general population, and no evidence has been found that their infants exhibit adverse effects. Yet, there remains substantial hesitation among this population globally regarding the safety of these vaccines. Herein we aimed to determine if compositional changes in milk occur following infection or vaccination, including any evidence of vaccine components. Using an extensive multi-omics approach, we found that compared to unvaccinated individuals SARS-CoV-2 infection was associated with significant compositional differences in 67 proteins, 385 lipids, and 13 metabolites. In contrast, COVID-19 vaccination was not associated with any changes in lipids or metabolites, although it was associated with changes in 13 or fewer proteins. Compositional changes in milk differed by vaccine. Changes following vaccination were greatest after 1-6 hours for the mRNA-based Moderna vaccine (8 changed proteins), 3 days for the mRNA-based Pfizer (4 changed proteins), and adenovirus-based Johnson and Johnson (13 changed proteins) vaccines. Proteins that changed after both natural infection and Johnson and Johnson vaccine were associated mainly with systemic inflammatory responses. In addition, no vaccine components were detected in any milk sample. Together, our data provide evidence of only minimal changes in milk composition due to COVID-19 vaccination, with much greater changes after natural SARS-CoV-2 infection.

Loneliness during the last phase of the COVID-19 pandemic in China: Trajectories, predictors, and impact on adolescent mental health (preprint)

Background Little is known about the long-term courses of loneliness, associated risk factors and effect on mental health in adolescents during the COVID-19 pandemic. This study aimed to explore the trajectories of loneliness among Chinese adolescents during the last phase of the pandemic. We also aimed to identify risk factors in each loneliness course and the impact of loneliness on emotional problems, peer problems, hyperactivity and conduct problems. Methods  We conducted longitudinal analyses using four waves of data from 2347 Chinese adolescents covering a period of 20 months (October 2021 – May 2023). Loneliness was assessed using the UCLA 3-Item Loneliness Scale. The self-reported version of the Strengths and Difficulties Questionnaire was utilized to evaluate participants’ mental health outcomes. Growth mixture modelling was employed to identify latent classes of loneliness trajectories. Associated risk factors were investigated using multinomial logistic regression model. Mixed-effects logistic regression models were constructed to examine the long-term impact of loneliness classes on mental health outcomes. Results Three courses of loneliness were identified: Decreasing Low Loneliness (58.71%), Increasing Medium Loneliness (36.52%), and Increasing High Loneliness (4.77%). Risk factors for poorer loneliness trajectories included lack of physical exercise habits, poorer mental health literacy, medium or low perceived social support, having study difficulties, being female, higher grades, and lower economic status. Loneliness courses were associated with the severity and variability of emotional problems, peer problems, hyperactivity and conduct problems. Individuals in the higher loneliness classes experienced a significant increase in these mental health problems over time. Conclusions  During the last phase of the pandemic, a large proportion of adolescents in our study endured medium to high levels of loneliness with no signs of improvement. Both unfavorable loneliness trajectories adversely affected internalizing and externalizing problems and displayed an upward trend in these difficulties. Results highlight the importance of considering how to tackle loneliness both within the context of COVID-19 and more generally.

In Vivo Antiviral Efficacy of LCTG-002, a Pooled, Purified Human Milk Secretory IgA product, Against SARS-CoV-2 in a Murine Model of COVID-19 (preprint)

Immunoglobulin A (IgA) is the most abundant antibody (Ab) in human mucosal compartments including the respiratory tract, with the secretory form of IgA (sIgA) being dominant and uniquely stable in these environments. sIgA is naturally found in human milk, which could be considered a global resource for this biologic, justifying the development of human milk sIgA as a dedicated airway therapeutic for respiratory infections such as SARS-CoV-2. In the present study, methods were therefore developed to efficiently extract human milk sIgA from donors who were either immunologically naive to SARS-CoV-2 (pooled as a control IgA) or had recovered from a PCR-confirmed SARS-CoV-2 infection that elicited high-titer anti-SARS-CoV-2 Spike sIgA Abs in their milk (pooled together to make LCTG-002). Mass spectrometry determined that proteins with a relative abundance of 1.0% or greater were all associated with sIgA. None of the proteins exhibited statistically significant differences between batches. Western blot demonstrated all batches consisted predominantly of sIgA. Compared to control IgA, LCTG-002 demonstrated significantly higher binding to Spike, and was also capable of blocking the Spike - ACE2 interaction in vitro with 6.3x greater potency compared to control IgA (58% inhibition at ~240ug/mL). LCTG-002 was then tested in vivo for its capacity to reduce viral burden in the lungs of K18+hACE2 transgenic mice inoculated with SARS-CoV-2. LCTG-002 was demonstrated to significantly reduce SARS-CoV-2 titers in the lungs compared to control IgA when administered at either 250ug/day or 1 mg/day, as measured by TCID50, plaque forming units (PFU), and qRT-PCR, with a maximum reduction of 4.9 logs. This innovative study demonstrates that LCTG-002 is highly pure, efficacious, and well tolerated in vivo, supporting further development of milk-derived, polyclonal sIgA therapeutics against SARS-CoV-2 and other mucosal infections.

The secretory IgA (sIgA) response in human milk against the SARS-CoV-2 Spike is highly durable and neutralizing for at least 1 year of lactation post-infection (preprint)

Although in the early pandemic period, COVID-19 pathology among young children and infants was typically less severe compared to that observed among adults, this has not remained entirely consistent as SARS-CoV-2 variants have emerged. There is an enormous body of evidence demonstrating the benefits of human milk antibodies (Abs) in protecting infants against a wide range of enteric and respiratory infections. It is highly plausible that the same holds true for protection against SARS-CoV-2, as this virus infects cells of the gastrointestinal and respiratory mucosae. Understanding the durability of a human milk Ab response over time after infection is critical. Previously, we examined the Abs present in milk of those recently infected with SARS-CoV-2, and concluded that the response was secretory IgA (sIgA)-dominant and that these titers were highly correlated with neutralization potency. The present study aimed to monitor the durability of the SARS-CoV-2 IgA and secretory Ab (sAb) response in milk from COVID-19-recovered lactating individuals over 12 months, in the absence of vaccination or re-infection. This analysis revealed a robust and durable Spike-specific milk sIgA response, that at 9-12 months after infection, 88% of the samples exhibited titers above the positive cutoff for IgA and 94% were above cutoff for sAb. Fifty percent of participants exhibited less than a 2-fold reduction of Spike-specific IgA through 12 months. A strong significant positive correlation between IgA and sAb against Spike persisted throughout the study period. Nucleocapsid-specific Abs were also assessed, which revealed significant background or cross reactivity of milk IgA against this immunogen, as well as limited/inconsistent durability compared to Spike titers. These data suggests that lactating individuals are likely to continue producing Spike-specific Abs in their milk for 1 year or more, which may provide critical passive immunity to infants against SARS-CoV-2 throughout the lactation period.

Comparative profiles of SARS-CoV-2 Spike-specific milk antibodies elicited by COVID-19 vaccines currently authorized in the USA (preprint)

Three COVID-19 vaccines are licensed for emergency use in the USA: the Pfizer/BioNTech and Moderna/NIH mRNA-based vaccines, and the Johnson & Johnson (J&J)/Janssen human adenovirus (Ad26) vaccine. These vaccines have immunized ~160 million people nationwide, comprising ~53% Pfizer, 39% Moderna, and 8% J&J recipients [1]. Although at varying stages of clinical investigation for use in children, no COVID-19 vaccines are yet available for this population, posing a significant public health concern. One method to protect infants and young children may be passive immunization via antibodies (Abs) provided in the milk of a lactating vaccinated person. Our early work [2] and other recent reports [3-5] examining the milk Ab response to mRNA-based COVID-19 vaccination have demonstrated that unlike the post-SARS-CoV-2 infection milk Ab profile, which is rich in specific secretory (s)IgA, the vaccine response is highly IgG-dominant. In this report, we present a comparative assessment of the milk Ab response elicited by not only the Pfizer and Moderna vaccines, but importantly, the J&J vaccine as well. This analysis revealed that compared to mRNA vaccine recipients, 49% - 63% fewer J&J vaccine recipient milk samples were positive for Spike-specific IgG, with positive samples exhibiting significantly lower mean IgG titers. J&J recipient milk samples contained significantly less specific IgA than Moderna recipient milk samples, which exhibited significantly greater relative IgA increases compared to both Pfizer and J&J recipients. Absolute and relative vaccine-induced secretory Ab titers were similarly low for all groups, though ~25% more Moderna recipients exhibited a relative increase compared to Pfizer and J&J recipients. These data indicate that J&J vaccine poorly elicits Spike-specific Ab in milk compared to mRNA-based vaccines and that this vaccine should be considered a last choice for immunizing those intending to elicit a strong Ab response in their milk. These data also suggest that Moderna vaccine elicits a superior, albeit moderate, milk (s)IgA response, and highlight the need to design vaccines with optimal protection of the breastfeeding infant in mind.