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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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Why Your Anxiety Could Be Linked to Your Gut Health

Have you ever had “butterflies in your stomach” before a big event? Or felt your stomach twist when you’re nervous? These feelings are more than just expressions. They reveal a real connection between your brain and your gut. Today, science is uncovering fascinating links between gut health and mental health—especially anxiety. Let’s explore how your gut might be silently affecting your mood and why it’s so important to keep it healthy.

The Gut-Brain Connection: More Than You Think

The gut and brain are connected through a network known as the gut-brain axis. This communication highway uses nerves, hormones, and chemicals to send messages between the two. The vagus nerve, the longest cranial nerve, plays a key role in this connection. It runs from your brain to your abdomen and helps regulate digestion, mood, and even immune response.

This means your brain can affect your gut—and your gut can affect your brain.

Meet Your Second Brain: The Gut Microbiome

Your gut is home to trillions of bacteria, fungi, and other microorganisms. This complex ecosystem is called the gut microbiome. It helps you digest food, absorb nutrients, fight harmful germs, and even create important chemicals.

Surprisingly, many of these chemicals influence your mood. One key player is serotonin, a “feel-good” hormone. Did you know that about 90% of serotonin is made in the gut? So, if your gut is unhealthy, your mood could suffer too.

How Gut Health Affects Anxiety

When your gut microbiome is balanced, you feel good—physically and mentally. But when it’s out of balance (a condition called dysbiosis), problems can begin.

1. Inflammation

An unhealthy gut can cause inflammation throughout the body, including the brain. This inflammation can interfere with normal brain function and contribute to anxiety and other mood disorders.

2. Leaky Gut Syndrome

If the gut lining becomes too weak, harmful bacteria and toxins can leak into the bloodstream. This is known as leaky gut. These toxins may trigger inflammation and affect your nervous system, increasing feelings of stress and anxiety.

3. Poor Nutrient Absorption

The gut absorbs nutrients like magnesium, B vitamins, and omega-3s—all of which are essential for brain health. If your gut isn’t working well, your brain might not get what it needs to stay calm and balanced.

4. Chemical Imbalance

The gut produces neurotransmitters like dopamine and serotonin. An imbalance in gut bacteria can disrupt their production, potentially leading to anxiety, depression, or mood swings.

Signs Your Gut Might Be Affecting Your Mental Health

If you’re struggling with anxiety, it’s worth asking whether your gut could be involved. Here are some signs your gut health might be impacting your mood:

Frequent bloating or gas
Constipation or diarrhea
Sugar cravings
Food intolerances
Brain fog or difficulty concentrating
Feeling tired all the time
Poor sleep quality

If you have both anxiety and digestive issues, the two could be connected.

How to Improve Gut Health and Reduce Anxiety

Thankfully, you can take simple steps to support your gut health—and improve your mental well-being along the way.

1. Eat More Fiber

Fiber feeds the good bacteria in your gut. Add more fruits, vegetables, whole grains, and legumes to your diet. Foods like apples, bananas, carrots, oats, and lentils are excellent choices.

2. Include Probiotics and Prebiotics

Probiotics are live bacteria that help balance your gut microbiome. You can find them in yogurt, kefir, kimchi, sauerkraut, and miso. Prebiotics, on the other hand, are foods that feed your good bacteria—like garlic, onions, and bananas.

3. Limit Processed and Sugary Foods

Sugar and highly processed foods can promote bad bacteria and inflammation. Try to reduce your intake of soft drinks, white bread, fast food, and sweets.

4. Manage Stress

Chronic stress can disrupt gut health. Practice stress-reducing techniques like deep breathing, meditation, yoga, or even spending time in nature.

5. Exercise Regularly

Physical activity helps regulate the gut microbiome and boosts mood-enhancing chemicals in the brain. Aim for at least 30 minutes of moderate exercise most days.

6. Get Enough Sleep

Poor sleep affects both gut health and mental health. Aim for 7–9 hours of quality sleep every night. A relaxing bedtime routine can help.

7. Stay Hydrated

Water helps keep your digestion smooth and your gut bacteria balanced. Drink at least 8 glasses of water a day.

8. Consider Supplements (If Needed)

If dietary changes aren’t enough, consider talking to a healthcare provider about probiotic or vitamin supplements. Don’t self-medicate—always consult a professional first.

When to See a Doctor

If you’re experiencing severe anxiety, depression, or digestive problems, don’t ignore it. A doctor or mental health professional can help you find the right treatment. In some cases, therapy, medication, or medical tests may be necessary.

Also, a nutritionist or gastroenterologist can help you identify and manage any gut-related issues contributing to your mental health symptoms.

Final Thoughts

Your gut is not just about digestion—it plays a powerful role in how you feel emotionally. Modern research shows that keeping your gut healthy can positively impact anxiety and overall mental well-being.

By taking simple steps to support your digestive system—like eating well, managing stress, and getting enough sleep—you can help improve both your gut and your mind.

Conclusion

In today’s fast-paced world, taking care of your mental health is more important than ever. And one of the most overlooked ways to do that is by taking care of your gut. From serotonin production to inflammation control, your gut plays a major role in how you feel every day. So next time you're feeling anxious, take a moment to think about your digestive health too. After all, it’s not just in your head—it could be in your stomach too.

If you're wondering why your anxiety could be linked to your gut health, it's time to start listening to your gut and making changes that support your entire well-being.

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