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Published on: Apr 20, 2020
3 minute read
By: Dr Rajan Choudhary

Is Herd Immunity A Valid Strategy For COVID 19?

Yesterday we explained you what Herd Immunity means and how it works, today we will take the discussion further to determine whether it is effective and can be recommended in the current context.

COVID-19 currently does not have a cure or a vaccine. Lockdown is the only strategy that appears to be working. Could implementing policies that encourages herd immunity be used to accelerate immunity in the population without the need for a vaccine?

INFECTIVITY

For the strategy to work we need to know a few things about the virus. How infective is it? In one of our earliest blogs we discussed infectivity at length and determined that the R0 (infectivity) may be between 2 and 3. This means each person with the virus can infect around 2-3 people at a time. Whilst this is not as high as Mumps (10-12) it is much higher than the common flu. The higher the R0 the more people that need to be immunised before herd immunity is achieved. For COVID it is estimated that 70% of the population need to be infected.

This is based off our current testing. Due to shortages in testing kits, only testing those that have a high likelihood of being infected and poorly organised testing infrastructure in some countries, we are likely underestimating. The number of people infected may be much higher as we are missing those that are asymptomatic but still have the disease and are still passing the disease on.

MORTALITY

Secondly, we need to know the mortality from COVID-19. Early estimates of mortality were as high as 10%, as we had little data on how many people were truly infected, but as the number of infected cases rose, and testing amongst the infected and symptomatic population rose, a more accurate mortality has been found to be around 1%. There is a risk we may still be underestimating the true mortality, as some cities have noted a spike in cardiac deaths, and some evidence supports possible cardiac damage due to COVID. But from the data we have, we know its mortality is lower than MERS (34%) and SARS (10%) but more than influenza (0.1%).

estimates of the COVID-19 case fatality rate

Whilst we have some data on who is likely to suffer from severe COVID symptoms (elderly, immunocompromised, people with heart or lung problems) we still cannot accurately determine who will get severe COVID in the “low risk” population. Simply because someone is young and healthy does not mean they will not die from COVID.

LENGTH OF IMMUNITY

Third we need to know how long this immunity will last. Similar coronaviruses responsible for the common cold usually create immunity that lasts for a few months, which is why we often get the cold repeatedly. A virus is also very prone to mutations that can change the structure and functions of its proteins, proteins responsible for tagging, latching on to and entering cells. If the structure of these proteins changes enough, then our antibodies will not be able to bind on, and new types of antibodies will have to be made with a slightly different structure. This effectively means our bodies have to start from step 1 again to create immunity, and we have to make new vaccines. This mutation rate is why we have to make new vaccines every season for the flu.

LONG TERM COMPLICATIONS

Finally, we need to know if there are any long-term implications from a viral infection. Again, this is something we do not know yet, as the virus has only been around for a few months. There may be implications for the cardiovascular system, long term breathing problems or more. And even if the complication rate appears relatively low (say, 1%), if millions of people are allowed to get infected, by definitions thousands or tens of thousands of people will have these complications, complications that can lead to issues later in life or an early death.

CONCLUSION

So, is herd immunity a viable strategy for COVID? Without a safe vaccine the general consensus appears to be no.

We don’t know how infective the virus really is or how many people it has infected

A 1% death rate is still very high. This means for every 100 people to be infected; one will die. This would mean hundreds of thousands of people dead in a country with a population over 10 million. It is unacceptably high.

If the death rate is 1%, then hospitalisation rate is likely higher. Almost all countries do not have capacity to have 1% of the population in hospital. Overwhelming the healthcare system will lead to poorer care, and worse care for those who do not have COVID. Leading to more people coming to serious harm or dying as a result of poor healthcare, not because of COVID.

We don’t know the long-term effects of COVID. By purposefully infecting people instead of waiting for a vaccine we may be causing unnecessary damage to a person’s health that only becomes apparent later in life. But this is speculation as we do not currently know if COVID has long term effects,

We don’t know if all of the risks above will amount to anything. The immunity may not last long enough, leading to another spike in infections and mortality.

Mass vaccination appears to be the safest strategy. And though human clinical trials have started on a number of vaccines, we are still months away from deployment. Until then we should not come out of lockdown prematurely, not until we have received an unbiased assessment from public health officials that states it is safe.

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Health Risks of Sedentary Lifestyle: Why Sitting Too Much Can Harm Your Health

Modern lifestyles have become increasingly sedentary. With the rise of desk jobs, digital devices and long working hours, many individuals spend a significant portion of their day sitting. While technology and convenience have improved productivity, they have also contributed to reduced physical activity.

Understanding the health risks of a sedentary lifestyle is essential for preventing chronic diseases and maintaining overall wellbeing.

What Is a Sedentary Lifestyle?

A sedentary lifestyle refers to a pattern of behavior characterized by prolonged sitting or inactivity with minimal physical movement.

Common examples include:

Sitting at a desk for long hours
Watching television for extended periods
Spending significant time on computers or smartphones
Limited engagement in physical exercise

When the body remains inactive for long durations, various physiological functions may become impaired.

1. Increased Risk of Obesity

Physical inactivity reduces calorie expenditure.

When calorie intake exceeds the energy burned through activity, excess calories are stored as body fat.

This can lead to weight gain and increase the risk of obesity.

Obesity is a major risk factor for several chronic health conditions.

2. Higher Risk of Cardiovascular Disease

Prolonged sitting has been associated with increased risk of heart disease.

Sedentary behavior may contribute to:

Elevated blood pressure
Increased cholesterol levels
Reduced blood circulation

These factors increase the likelihood of cardiovascular complications over time.

3. Increased Risk of Type 2 Diabetes

Physical activity helps regulate blood sugar levels.

A sedentary lifestyle may impair the body’s ability to use insulin effectively, leading to insulin resistance.

Over time, this can increase the risk of developing type 2 diabetes.

4. Poor Metabolic Health

Metabolism refers to the body’s ability to convert food into energy.

Long periods of inactivity may slow metabolic processes and reduce the body’s efficiency in managing glucose and fat levels.

This can contribute to metabolic syndrome.

5. Musculoskeletal Problems

Sitting for extended periods can strain muscles and joints.

Common issues include:

Lower back pain
Neck stiffness
Shoulder discomfort
Poor posture

These problems are particularly common among office workers.

6. Reduced Mental Wellbeing

Physical activity plays a significant role in supporting mental health.

Sedentary behavior may contribute to:

Increased stress levels
Reduced mood
Lower energy levels

Regular movement helps improve mental wellbeing.

7. Increased Risk of Premature Mortality

Studies have shown that prolonged inactivity may increase the risk of early death due to chronic diseases.

Maintaining an active lifestyle significantly improves long-term health outcomes.

Sedentary Lifestyle in the Indian Context

Urbanization and technological advancements have led to more sedentary work environments in India.

Long commuting hours, desk-based professions and digital entertainment have reduced physical activity levels for many individuals.

As a result, lifestyle-related diseases such as diabetes and heart disease have increased significantly in recent years.

Public health initiatives now emphasize the importance of regular physical activity to counter these trends.

How to Reduce Sedentary Behavior

Take Frequent Movement Breaks

Stand up and stretch every 30–60 minutes during work.

Incorporate Walking into Daily Routine

Short walks during breaks can improve circulation and energy levels.

Use Active Workstations

Standing desks or adjustable workstations encourage movement.

Exercise Regularly

Engage in moderate physical activity such as walking, cycling or yoga.

Health guidelines recommend at least 150 minutes of exercise per week.

Limit Screen Time

Reducing recreational screen time encourages more active habits.

Benefits of an Active Lifestyle

Increasing daily physical activity provides several health benefits:

Improved cardiovascular health
Better weight management
Enhanced mental wellbeing
Stronger muscles and bones
Improved metabolic function

Even small lifestyle changes can make a significant difference over time.

When to Seek Medical Advice

Consult a healthcare professional if you experience:

Persistent back pain
Unexplained weight gain
Chronic fatigue
Signs of metabolic disorders

Early intervention can help manage health risks effectively.

Conclusion

A sedentary lifestyle may significantly impact physical and mental health. Prolonged sitting and lack of movement increase the risk of obesity, cardiovascular disease, diabetes and musculoskeletal problems.

Adopting an active lifestyle that includes regular movement, exercise and healthy habits is essential for maintaining overall wellbeing.

Simple changes such as standing frequently, walking regularly and engaging in physical activity can greatly reduce the health risks associated with sedentary behavior.

Maintaining an active lifestyle is one of the most effective ways to support long-term health and prevent chronic disease.

References

World Health Organization – Physical Activity Guidelines
Indian Council of Medical Research – Lifestyle Disease Reports
National Family Health Survey – Health and Lifestyle Data
Lancet Global Health – Sedentary Behavior Research
Journal of Preventive Medicine – Physical Activity Studies

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