COVID-19 Lockdowns: Impact on Immune Response Post-Pandemic

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Study finds people's immune systems reacted more intensely against the microorganisms causing inflammation after the COVID-19 pandemic ().

Research from Radboud University Medical Center has examined the effects of lockdowns and vaccinations introduced during the pandemic. The study found that inflammation biomarkers in the blood were low during the lockdown for people living with HIV and healthy individuals.

‘Overreactivity of the immune system post-pandemic has increased #inflammation and allergies. #covid19 #medindia ’

However, the immune cells from the blood had a stronger reaction to microorganisms like viruses and bacteria in the lab than the immune cells of individuals outside the lockdown. The study results are published in Frontiers in Immunology.

How Lockdowns Disrupted Our Immune Balance

As a possible explanation for this strong immune reaction, Professor Mihai Netea from Radboud University Medical Center points to the hygiene hypothesis. This hypothesis suggests that regular contact with microorganisms is beneficial because it keeps the immune system both active and tolerant at the same time. A lack of exposure to environmental factors might contribute to an immune system that overreacts, potentially leading to systemic reactions such as those encountered in inflammatory diseases and allergies.

In our daily lives, we are constantly exposed to various microorganisms. This helps train our immune system, teaching it to recognize which microorganisms are dangerous and which are harmless. During the lockdown, we missed that interaction because everyone stayed home and avoided each other. As a result, during and immediately after the lockdown periods, immune cells exposed to microorganisms displayed a less well-regulated response, predisposing to hyperinflammation.

Impact of COVID-19

This research was made possible through a large study on people with HIV, initiated by Radboudumc and three other HIV treatment centers in the Netherlands. Recruitment for the study took place between October 2019, just before the COVID-19 pandemic, and October 2021. A total of 1,895 people with HIV are participating in this study, which is part of a broader research project on immune system function and the diversity of immune responses.

The study participants were divided into four groups:

• 368 individuals enrolled before the pandemic
• 851 individuals enrolled after the lockdown, but before vaccination or a COVID-19 infection
• 175 individuals who had contracted a COVID-19 infection
• 404 vaccinated individuals

In the lab, the researchers measured the level of inflammation in the participants' blood. They also examined the interaction between isolated blood cells and viruses and bacteria.

Subsequently, the findings were validated in a cohort of 30 healthy individuals tested during or after the lockdown period. The results of this study primarily reflect people living with HIV, but we also examined a healthy control group. We saw similar results in this group, suggesting the effects may apply to the wider population. However, more research is needed for this group.

Lockdowns vs. Vaccines

The study also revealed that vaccines and a COVID-19 infection influenced the immune system's response. Still, these effects were relatively small and short-lived, and were negligible compared to the impact of the lockdowns on the immune system.

Lockdowns were necessary during the pandemic, especially at the beginning. However, we must gain more insight into how social interactions affect and activate our immune system, so we can better manage the consequences. This way, we can apply such drastic social measures effectively and safely in a future pandemic.

Reference:

1. Covid-19 a triggering factor of autoimmune and multi-inflammatory diseases - (https:pmc.ncbi.nlm.nih.gov/articles/PMC9969758/)

Source: Eurekalert