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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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Importance of Hydration for Organs: How Water Keeps the Body Functioning

Water is the most essential nutrient for human survival, yet it is often the most neglected. Every cell, tissue and organ in the body depends on adequate hydration to function properly. The importance of hydration for organs becomes clear when we understand how even mild dehydration can disrupt critical physiological processes.

In India’s climate, with high temperatures and humidity in many regions, dehydration risk is especially high, making conscious hydration a daily health priority.

Why Water Is Vital for the Human Body

The human body is made up of approximately 60 percent water. This water:

transports nutrients and oxygen
regulates body temperature
removes waste products
supports metabolic reactions

Without adequate hydration, organ systems begin to struggle.

Hydration and Kidney Health

The kidneys are among the most hydration-dependent organs.

Proper hydration:

helps kidneys filter blood efficiently
flushes out toxins and waste
reduces risk of kidney stones

Chronic dehydration forces kidneys to concentrate urine, increasing strain and long-term damage risk. According to Indian Council of Medical Research data, dehydration is a major contributor to kidney stone formation in India.

Brain Function and Hydration

The brain is highly sensitive to hydration levels.

Even mild dehydration can cause:

headaches
difficulty concentrating
memory issues
irritability

Studies published in the Lancet show that dehydration negatively affects cognitive performance and mood, even before thirst becomes noticeable.

Heart and Circulatory System

Hydration plays a critical role in cardiovascular health.

Adequate water intake:

maintains blood volume
supports smooth circulation
reduces strain on the heart

Dehydration thickens blood, making the heart work harder and potentially increasing the risk of low blood pressure, dizziness and cardiovascular stress.

Digestive System and Hydration

Water supports digestion at every stage.

It helps:

break down food
absorb nutrients
prevent constipation

Chronic low water intake is linked to digestive discomfort, bloating and poor gut motility.

Liver Function and Detoxification

The liver relies on water to:

metabolise nutrients
detoxify harmful substances
support metabolic balance

Inadequate hydration slows detoxification processes and increases metabolic strain.

Muscle and Joint Health

Muscles and joints contain significant water content.

Hydration:

prevents muscle cramps
supports joint lubrication
reduces injury risk

Dehydrated muscles fatigue faster and recover more slowly.

Skin as an Organ and Hydration

The skin is the body’s largest organ.

Adequate hydration:

maintains skin elasticity
supports barrier function
reduces dryness and irritation

While water alone is not a cure for skin problems, chronic dehydration worsens skin health.

Hydration and Immune Function

Water supports immune health by:

enabling transport of immune cells
aiding removal of toxins
supporting lymphatic circulation

WHO recognises hydration as a foundational element of immune system support.

Effects of Dehydration on Multiple Organs

Dehydration affects the body systemically.

Common effects include:

fatigue
dizziness
reduced urine output
dark-coloured urine
dry mouth and eyes

Severe dehydration can lead to organ failure if untreated.

Why Dehydration Often Goes Unnoticed

Many people confuse thirst with hunger or fatigue.

Risk factors include:

busy work schedules
excessive caffeine intake
high temperatures
inadequate fluid intake

By the time thirst is felt, dehydration has already begun.

Hydration Needs Vary by Individual

Water requirements depend on:

age
body size
physical activity
climate
health conditions

General guidelines suggest 2–3 litres daily for adults, but individual needs may vary.

Hydration and Chronic Disease Prevention

Proper hydration supports prevention of:

kidney disease
urinary tract infections
constipation
heat-related illness

NITI Aayog and WHO highlight hydration as a basic preventive health measure.

Best Practices for Staying Hydrated

Effective hydration strategies include:

drinking water regularly throughout the day
increasing intake during heat or physical activity
consuming water-rich foods such as fruits and vegetables
limiting sugary and caffeinated beverages

Consistency matters more than quantity in a single sitting.

Signs You May Need More Water

Watch for:

frequent fatigue
headaches
dry skin
reduced urination
poor concentration

These are early indicators of dehydration.

Role of Preventive Health Awareness

Preventive healthcare focuses on simple daily habits.

Hydration:

costs nothing
supports every organ
reduces disease risk

Small habits deliver large long-term benefits.

When to Seek Medical Advice

Consult a healthcare professional if experiencing:

persistent dehydration symptoms
kidney or urinary issues
dizziness or fainting
chronic fatigue

Underlying conditions may require medical evaluation.

Conclusion

The importance of hydration for organs cannot be overstated. Water supports kidney filtration, brain function, heart circulation, digestion, immunity and overall metabolic balance. Even mild dehydration disrupts organ performance and increases health risks over time. In busy modern lifestyles, consciously prioritising daily hydration is one of the simplest and most effective ways to protect vital organs and maintain long-term health. Consistent water intake is not just a habit—it is a foundation for organ health and wellbeing.

References

Indian Council of Medical Research (ICMR) – Hydration and Kidney Health Studies
World Health Organization (WHO) – Water Intake and Health Guidelines
National Family Health Survey (NFHS-5) – Nutrition and Lifestyle Data
Lancet – Hydration, Cognitive Function and Organ Health Research
NITI Aayog – Preventive Healthcare and Lifestyle Recommendations
Statista – Global Hydration and Health Trends

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