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Life Before COVID: You May Remember it, but Does Your Immune System?

Updated: Aug 17, 2023

Even now while the COVID-19 pandemic appears to be turning the corner, rising case counts reveal the volatility of the situation. Despite the vaccine rollout in the United States being well underway, 15 states currently face rising COVID cases. Throughout the pandemic, the effectiveness of long-term quarantine and social distancing measures have been called into question by political and community leadership at various levels. One popular criticism of extended lockdown orders is the possibility of reduction in immune system function and one’s ability to fight off new infections as a result of lack of exposure to viruses and bacteria. This would mean that the stay at home orders that have been consistent throughout the pandemic may leave people worse off due to their susceptibility to new and old pathogens alike when and as they reenter society. At first glance, the theory intuitively makes sense. Just like many physiological processes in our body, the concept of “if you don’t use it, you lose it” becomes all too real when we start that run or do those pushups we haven’t done in months. However, luckily for us, our immune system may not work quite the same way.

[1]. In terms of antiviral response, one study found that the half-lives of antibody responses against certain viruses ranged from 50 to 200 years after the development of immunity[2]. Unless we plan to be in lockdown for the next 50 years, it’s unlikely our immune system will lose its ability to protect us from viruses. In the context of quarantine, your body’s immune system does not need continued exposure to maintain optimal function.

So no issues, then?

However, this does not mean that quarantine and lockdown measures have no adverse effect on the immune system or our overall health. It is well understood that one’s physical activity level and diet have a significant effect on the innate and adaptive immune system capability. COVID-19 has had a dramatic effect on people’s daily activity levels and their ability to use exercise facilities like gyms. A study from the beginning of the pandemic used health app data to reveal a total reduction of 25% in steps per day worldwide. The worsening of people’s diets due to artificial food shortages and stressful eating patterns compounds the effects of reduction in physical activity. One study based in the United States found that there were significant increases in restrictive eating, meal skipping, and overeating, leading to 30% of people reporting that their diet had worsened because of the pandemic[3]. Physical exercise and a nutritious diet have both been shown to strengthen multiple levels of immune function[4]. Without proper diet and exercise, our body’s immune system cannot function to its best ability.

[5]. It is well understood that these adverse physiological and mental health effects can stifle immune function. Depressed patients express higher levels of corticotropin-releasing hormone (CRH), which has a negative effect on the both the cellular and innate immune system[6].

So, does the immune system forget?

Luckily for us, it does not. However, being under lockdown orders and quarantine can still affect our ability to fight off new infections, including COVID-19. Maintaining one’s physical and mental health throughout the pandemic has proved to be an important strategy along with social distancing and mask wearing. Although physical distancing measures have saved countless lives through the reduction of transmission, it’s important to understand their unintended consequences to inform government orders in the future. Going forward, government officials need to consider the protection of citizens from viral transmission, as well as adverse physical and mental effects due to lockdown orders.

By: John Etherton and Scott Gershman,


[1] Tison, G. H., Avram, R., Kuhar, P., Abreau, S., Marcus, G. M., Pletcher, M. J., & Olgin, J. E. (2020). Worldwide effect of COVID-19 on physical activity: a descriptive study. Annals of internal medicine, 173(9), 767-770.

[2] Amanna, I. J., Carlson, N. E., & Slifka, M. K. (2007). Duration of humoral immunity to common viral and vaccine antigens. New England Journal of Medicine, 357(19), 1903-1915.

[3] Khubchandani, J., Kandiah, J., & Saiki, D. (2020). The COVID-19 Pandemic, Stress, and Eating Practices in the United States. European Journal of Investigation in Health, Psychology and Education, 10(4), 950-956.

[4] Nieman, D. C., & Wentz, L. M. (2019). The compelling link between physical activity and the body’s defense system. Journal of sport and health science, 8(3), 201-217.

[5] Xiong, J., Lipsitz, O., Nasri, F., Lui, L. M., Gill, H., Phan, L., … & McIntyre, R. S. (2020). Impact of COVID-19 pandemic on mental health in the general population: A systematic review. Journal of affective disorders.

[6] Vasile, C. (2020). Mental health and immunity. Experimental and Therapeutic Medicine, 20(6), 1-1.

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