• Published on: Apr 19, 2020
  • 3 minute read
  • By: Dr Rajan Choudhary

What Is Herd Immunity With Respect To Covid19 ?

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Herd immunity: the basics

Many countries have been in lockdown for over a month, and some have tried to begin the discussion of an exit strategy. We know that remaining in lockdown continuously is not a feasible strategy, as many people have been suffering economic consequences from the stringent lockdown measures, and many countries have been providing significant monetary and fiscal support for people and businesses at risk. But leaving lockdown too early has its own consequences.

Almost all public health professionals will agree that the lockdown has been able to significantly reduce infection rates and reduce the pressure on our healthcare systems. By taking this early victory and prematurely ending lockdown we risk another wave of infections, reintroducing lockdown, and having an overall negative effect on the general health of the populous.

So what can we do? One exit strategy that has been touted recently is herd immunity. To understand how to may work for COVID we must understand what epidemiologists mean by herd immunity.

IMMUNITY

Our body’s immune system fights against invading organisms such as bacteria and viruses. For a more in-depth discussion you can have a look at previous blogs on Vaccines and Boosting the Immune system. The immune system is very competent and has mechanisms to theoretically recognise any protein tags that do not belong to that person’s cells, even protein tags that do not currently exist in nature. This gives the immune system the ability to theoretically recognise nearly any invading organism that has existed or will ever exist.

The immune system goes beyond this as well and produces “memory cells”. These remain in the blood after an infection for a long time; in some cases, it can even be lifelong. When a second infection occurs from the same organism the immune system jumps into action and is able to produce antibodies against the invader almost immediately. This can neutralise the invader before it has a chance to replicate, cause severe symptoms and harm the body. Sometimes we never realise we have been infected as the infection never gets a chance to cause any damage.

Importantly, if the invader cannot replicate in our body, then its ability to spread to other people is also reduced. For example, respiratory viruses can rapidly replicate in our lungs and be transmitted when we cough or sneeze. By eliminating the virus before it can replicate extensively the number of viral particles in each cough and sneeze is reduced, reducing the chances of another person catching the infection.

This is the basis of how vaccines work and is covered in depth in the two part blog.

HERD IMMUNITY

If our immune system is so competent, why do we need to worry about infections at all? Surely we can all get infected and gain immunity. In an ideal world where everyone was healthy this may be true. But there are many people who do not have fully functioning immune systems. These people are immunocompromised and can be for many reasons.

  • Chemotherapy and radiotherapy for cancer destroys rapidly dividing cells such as cancer cells. Unfortunately, it also hits other dividing cells, such as hair follicles, gut lining and the bone marrow, which produce the white blood cells that give us immunity. Chemotherapy patients are very susceptible to even the mildest of infections. Even if a mild infection is suspected, they are treated aggressively with antibiotics, as their lowered immune systems can become overwhelmed very quickly.
  • Sometimes doctors advise patients to take medication that purposefully dampens the immune system. This is necessary for transplant patients, where the host immune system attacks the donor organ as it does not belong to the host, or in autoimmune disorders, where the immune system attacks the host by mistakenly recognising it as an “invader”.
  • Taking steroids long term has a similar effect, and is used quite commonly for skin disorders, asthma, COPD, and other inflammatory conditions.
  • People with various chronic illnesses can have reduced immunity as a result of the illness. High sugar levels associated with poorly controlled diabetes can cause worsening organ function, including the immune system. These patients are more susceptible to infections.
  • Finally, some people do not have fully functioning or welldeveloped immune systems for a variety of reasons, inherited or acquired. As we get older, the immune system function decreases, and simple infections can be devastating.

In all of these cases the ability to recognise invading organisms, destroy them and form immunity is hampered. Vaccination, one way of inducing immunity without causing the person to suffer from a full-blown infection, can also be ineffective in these patients, and some vaccines can be dangerous if used incorrectly. So how do we protect these vulnerable patients?

HERD IMMUNITY

This is where we go back to the earlier point. Immunity in healthy people can reduce or even prevent the spread of infection from one person to another. The number of healthy people outnumber the number of vulnerable, immunocompromised ones. Therefore, if we induce immunity in most people, the infection will simply not spread to the vulnerable ones. We don’t have to immunise everyone, just enough to prevent transmission. This is called herd immunity. This is why we immunise everyone with flu vaccines even those that are healthy and will survive a full blown infection. Because by preventing these people from inadvertently spreading the flu, they will protect those that we cannot immunise.

Does herd immunity work? For most other diseases, yes. It depends on how the disease is spread, and how infective it is. For measles, you need to immunise 19 out of 20 people to achieve herd immunity, because it is so infective. But once herd immunity was achieved death rates were drastically reduced. With the advent of anti-vaccine campaigns, particularly against MMR, this herd immunity has been lost, and many vulnerable children (and adults) who do not have fully functioning immune systems are now contracting this virus and dying from a preventable disease.

It can be achieved for pandemics as well. Norway was able to achieve partial herd immunity to H1N1 (swine flu) through a vaccination program and natural immunity. Vaccines are the best method for achieving herd immunity without extremely high death rates. We have already covered the issues with making a vaccine, and why it takes such a long time, in our previous blog

From reading this blog you should now have an understanding of what herd immunity is, and why it is important in protecting those that are vulnerable to infections. In our next blog we will look at why herd immunity may not be the solution for COVID-19.

Dr Rajan Choudhary, UK, Chief Product Officer, Second Medic Inc

www.secondmedic.com

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Simple Habits to Avoid High Cholesterol

Simple Habits to Avoid High Cholesterol

High cholesterol is one of the leading causes of heart disease and stroke worldwide. In India, rising cholesterol levels are becoming more common due to sedentary lifestyles, unhealthy food habits, and stress. But the good news is—you can prevent high cholesterol naturally with a few simple habits.

In this blog, we’ll explore easy, everyday steps you can take to keep your cholesterol levels in check and protect your heart.

 

What Is Cholesterol?

Cholesterol is a fatty substance found in your blood. While your body needs some cholesterol to build cells and hormones, too much of the wrong type—called LDL (low-density lipoprotein)—can be harmful. It can build up in your arteries and increase your risk of heart disease and stroke.

There’s also HDL (high-density lipoprotein), which is the “good” cholesterol that helps remove LDL from your body.

 

Why High Cholesterol Is Dangerous

  • Clogs arteries and restricts blood flow
     

  • Increases risk of heart attacks and strokes
     

  • Can lead to high blood pressure
     

  • May affect kidney and liver function
     

The scariest part? High cholesterol usually has no symptoms. That’s why it’s called a silent killer and must be managed before problems begin.

 

7 Simple Habits to Avoid High Cholesterol

 

1. Eat Fiber-Rich Foods Daily

Soluble fiber binds with cholesterol in the gut and removes it from your body.

Best foods for fiber:

  • Oats and barley
     

  • Apples, pears, and oranges
     

  • Beans and lentils
     

  • Flaxseeds and chia seeds
     

Tip: Start your morning with a bowl of oatmeal and add a fruit—it’s a heart-healthy breakfast!

 

2. Stay Active Every Day

Physical activity boosts HDL (good cholesterol) and burns fat that raises LDL.

What to do:

  • Walk briskly for 30 minutes a day
     

  • Try yoga, cycling, or dancing
     

  • Use stairs instead of the lift
     

  • Take short walks after meals
     

Even small movements throughout the day matter.

 

3. Cut Down on Saturated & Trans Fats

These fats raise your LDL cholesterol quickly.

Avoid:

  • Fried food, chips, and baked snacks
     

  • Ghee-heavy sweets
     

  • Processed foods with “hydrogenated oils”
     

Choose instead:

  • Olive oil or mustard oil
     

  • Grilled or baked foods
     

  • Fresh fruits and nuts as snacks
     

 

4. Manage Your Stress

Stress affects your hormones and may raise your cholesterol over time.

Try this:

  • Practice deep breathing or meditation
     

  • Do relaxing hobbies like reading or gardening
     

  • Take tech breaks and sleep 7–8 hours daily
     

  • Talk to someone if you’re feeling overwhelmed
     

A calm mind supports a healthy heart.

 

5. Stay Hydrated and Cut Sugary Drinks

Water helps regulate body functions and weight, which both impact cholesterol.

Do this:

  • Drink 8–10 glasses of water daily
     

  • Avoid soft drinks and energy drinks
     

  • Switch to herbal teas or infused water
     

Too much sugar can raise triglyceride levels, a type of fat in your blood.

 

6. Quit Smoking and Limit Alcohol

Smoking lowers good cholesterol and damages arteries. Alcohol, in excess, can also spike cholesterol and blood pressure.

Tip:
Even reducing smoking or drinking frequency helps your heart function better.

 

7. Get Regular Cholesterol Tests

Don’t wait for symptoms. Get your lipid profile checked every year, especially if you have:

  • A family history of heart disease
     

  • Diabetes or high blood pressure
     

  • Obesity or unhealthy lifestyle habits
     

Suggested Test:
Lipid Profile Test by Thyrocare via SecondMedic.com – includes LDL, HDL, total cholesterol, and triglycerides with home sample collection.

 

Normal Cholesterol Levels:

Type

Ideal Range

Total Cholesterol

Below 200 mg/dL

LDL (Bad)

Below 100 mg/dL

HDL (Good)

Above 40 mg/dL (men), 50 mg/dL (women)

Triglycerides

Below 150 mg/dL

 

Tips to Book a Test via SecondMedic:

  1. Visit www.secondmedic.com
     

  2. Search for Lipid Profile Test – Thyrocare
     

  3. Select home collection
     

  4. Fast for 9–12 hours before the test
     

  5. Get results in 24–48 hours
     

 

Bonus Tips

  • Replace white rice with brown rice or millets
     

  • Choose low-fat milk and curd
     

  • Snack on almonds or walnuts
     

  • Cook at home more often than eating out
     

  • Maintain a healthy weight
     

 

Conclusion

You don’t need fancy diets or harsh treatments to manage cholesterol. Just a few simple daily habits can make a big difference in protecting your heart.

By eating better, moving more, managing stress, and staying hydrated, you can keep your cholesterol in check without medication in many cases.

Make your heart health a priority starting today!

Start following these simple habits to avoid high cholesterol and keep your heart happy for years to come.

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