New studies indicate that the lockdowns enforced during the COVID-19 pandemic greatly affected how our immune systems respond to various microorganisms. While levels of inflammation in the body were diminished during lockdown, the immune system exhibited a stronger reaction to viruses and bacteria afterward.
Research from Radboud University Medical Center has revealed that the lockdowns during the COVID-19 pandemic greatly influenced how people’s immune systems respond to microorganisms. Inflammation levels were lower while lockdowns were in place, but following them, the immune system showed a more vigorous response to viruses and bacteria. These findings are detailed in the journal Frontiers of Immunology.
Researchers looked into various health measures introduced during the pandemic, including lockdowns and vaccination efforts. Their study involved a large group of individuals living with HIV, as well as healthy participants. Findings indicated that during the lockdown, inflammation biomarkers were lower in both groups. However, when immune cells from these individuals were exposed to viruses and bacteria in laboratory settings, their immune responses were much stronger compared to those from individuals who were not under lockdown.
Hygiene Hypothesis
Professor Mihai Netea from Radboud University Medical Center suggests that this robust immune response may be explained by the hygiene hypothesis. This theory posits that regular exposure to microorganisms is advantageous as it keeps the immune system both active and tolerant. A lack of interaction with these microorganisms may lead to an immune system that overreacts, which can fuel systemic issues such as inflammatory diseases and allergies.
Netea stated, ‘In our everyday lives, we are consistently in contact with various microorganisms. This exposure helps train our immune system to differentiate between harmful and harmless entities. However, during the lockdown, this interaction was severely limited as everyone stayed home and avoided contact with one another. Consequently, during and right after the lockdown, immune cells that encountered microorganisms showed a less-regulated response, leading to a higher risk of hyperinflammation.’
Study Design
This research was facilitated by an extensive study on individuals with HIV, started by Radboudumc alongside three additional HIV treatment centers in the Netherlands. Recruitment for the study occurred between October 2019, right before the COVID-19 pandemic began, and October 2021. A total of 1,895 participants with HIV took part, which is part of a larger investigation into immune system functionality and its diverse responses.
Participants were categorized into four distinct groups:
- 368 individuals enrolled prior to the pandemic
- 851 individuals enrolled after the lockdown, but before vaccinations or COVID-19 infections
- 175 individuals who had contracted COVID-19
- 404 vaccinated individuals
In the laboratory, researchers measured inflammation levels in the blood of participants and studied how isolated blood cells interacted with viruses and bacteria.
Additionally, these results were confirmed in a group of 30 healthy individuals tested during or after the lockdown period. Professor Andre van der Ven remarked, ‘While the findings primarily represent individuals living with HIV, we also included a healthy control group. Similar results were noted in this group, suggesting that these effects may extend to the general population. Nevertheless, further research is required for this broader cohort.’
Awareness of Impact
The study also found that vaccinations and COVID-19 infections did have some influence on the immune response, but these effects were comparatively minor and short-lived, as explained by Netea. He emphasized that these impacts were negligible compared to the significant effects of the lockdowns on immune function. Netea concluded, ‘While lockdowns were crucial during the pandemic, especially at the outset, it is vital to understand how social interactions influence and stimulate our immune systems. This knowledge will help us better handle the repercussions of such drastic social measures in future pandemics.’
