• 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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Daily habits that increase uric acid silently

Daily habits that increase uric acid silently

High uric acid is often called a “silent lifestyle disease” because it builds up slowly in the body without obvious warning signs. By the time symptoms like severe joint pain or gout appear, uric acid levels are already high. Many people don’t realize that their daily habits play a huge role in increasing uric acid silently. Understanding these hidden triggers can help prevent complications like gout, kidney stones, and arthritis.

What Is Uric Acid and Why Does It Matter?

Uric acid is a natural waste product formed when the body breaks down purines, which are found in certain foods and drinks. Normally, kidneys filter out uric acid through urine. But when uric acid is produced in excess or not excreted properly, it accumulates in the blood—a condition known as hyperuricemia. Over time, uric acid crystals settle in joints and tissues, leading to pain, swelling, and even kidney issues.

1. Excess Consumption of Red Meat and Seafood

Animal proteins like red meat, organ meats, and seafood such as sardines and shellfish are high in purines. Eating them daily increases uric acid levels silently. While occasional consumption is fine, frequent intake increases the risk of gout flare-ups and kidney strain.

2. Sugary Drinks and Alcohol

Sugary sodas, packaged juices, and alcohol—especially beer—are major contributors to high uric acid. Fructose in sweet drinks boosts uric acid production, while alcohol reduces the kidneys’ ability to flush it out. This double impact silently raises uric acid, even if you don’t notice immediate symptoms.

3. Skipping Water and Poor Hydration

Water is crucial for flushing out waste, including uric acid. Drinking less than 2–3 liters of water daily reduces kidney efficiency. This habit silently increases uric acid build-up, leading to dehydration, kidney stones, and higher risk of gout attacks.

4. Sedentary Lifestyle

Lack of exercise slows metabolism and makes it harder for the body to process uric acid. A sedentary lifestyle also contributes to obesity, which is directly linked to higher uric acid levels. Even simple activities like daily walking, yoga, or stretching can improve uric acid balance.

5. Poor Sleep and Stress

Chronic stress and irregular sleep patterns disrupt hormonal balance, increasing inflammation in the body. Stress hormones interfere with kidney function, making it harder to eliminate uric acid effectively. Poor sleep also worsens weight gain, which indirectly impacts uric acid levels.

6. Overeating Processed Foods

Packaged foods, fried snacks, and processed meats often contain hidden purines, unhealthy fats, and high sugar. These not only affect digestion but also silently raise uric acid, especially when eaten regularly.

7. Ignoring Early Symptoms

One of the biggest mistakes is ignoring early signs such as mild joint stiffness, unexplained swelling, or fatigue. Since these symptoms often come and go, many people overlook them until uric acid levels are dangerously high.

How to Prevent Uric Acid Build-Up

  • Drink 2–3 liters of water daily.
     

  • Limit red meat, organ meats, and seafood.
     

  • Avoid sugary drinks and alcohol.
     

  • Include more vegetables, fruits, and whole grains in diet.
     

  • Exercise at least 30 minutes daily.
     

  • Manage stress with meditation, yoga, or deep breathing.
     

  • Go for regular health checkups and blood tests.
     

Conclusion

Uric acid is not just about gout—it affects your overall health, kidneys, and metabolism. The good news is that small changes in lifestyle can make a big difference. By avoiding daily habits that increase uric acid silently, you can protect your joints, kidneys, and long-term well-being.

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