Coronavirus vaccine offers more hope than ever before, so is herd immunity possible?  Or is the virus cleverer than we are?

Herd immunity is possible in two ways – by encouraging wide infection through the natural spread of the Coronavirus, or through vaccination.

Achieving natural herd immunity by encouraging infection will exact a heavy cost in terms of the numbers of cases and consequent mortality, particularly among the vulnerable, elderly and infirm.  This would also cause high mortality among ethnic minorities, including healthcare and long-term care workers – this being due to their tendency towards vitamin D deficiency and low socio-economic status.

However, we can also gain herd immunity through an effective Coronavirus vaccination programme with fewer adverse side effects.  Vaccination not only prevents infection but, if infection does occur, it also reduces the severity and lowers the risk of mortality.

We are dealing with a brand-new virus that we don’t know much about.  We are still on the steep part of the learning curve.  We have a 50:50 chance of making the right decision.  It would be sensible at this stage to lock everything down until enough information becomes available.  Countries like Singapore, Hong Kong, South Korea and Australia “won the game” by taking this logical step, while US and Sweden did not.

Because the Coronavirus is on a learning curve too!

The virus is at the same stage of knowledge about our bodies, as we are about it.  It is frequently changing its structure to produce more efficient strains to gain faster and easier access to our cells.

The UK government adopted a natural herd immunity strategy early in the pandemic, hoping to gain this immunity without damaging the economy.  Now the other option of gaining it through an effective vaccination program has become available.

This article is going to discuss herd immunity as a valuable public health measure to control Covid-19 infection, to reduce the severity of the disease and to lower the associated high mortality among the vulnerable population.  We will also discuss Coronavirus vaccination – how the vaccine works, the options available and the impact of the new strains on the effectiveness of the current vaccines.

At the start of the pandemic, the government did its best to produce a balanced decision based on the desire to maintain the economy and in response to pressure from the public and the scientific community in view of the sharp rise in cases and mortality (now over 100,000 in the UK.)  Scientists and doctors were split: some supported natural herd immunity; others were against it.

We have learnt things from the public health measures taken during the pandemic.  The most effective include social distancing, face masks and hand washing.  The success of controlling the infectious disease also rests on widespread testing to detect and isolate patients and their contacts.

The government can and have used additional measures, on and off, like cancelling mass gatherings, and closing schools and colleges.  People with respiratory symptoms and other chronic health issues have been asked to stay at home.

These measures can continue to save lives until the vaccination program has fully rolled out.

What is herd immunity?

The World Health Organisation (WHO) defines ‘herd immunity’, also known as ‘population immunity,’ as the indirect protection from an infectious disease that happens when a population is immune either through vaccination or immunity developed through previous infection.  WHO supports achieving ‘herd immunity’ through vaccination, not by allowing a disease to spread through any segment of the population, as this would result in unnecessary cases and deaths.

Herd immunity depends on the rate of transmission of the infectious disease.  For Covid-19, it is estimated that 60-70% of the population need to gain immunity to protect the rest of the community.  (The figure is 95% for measles!)  This means in the UK, you need 40 million people to gain immunity, either through natural infection or vaccination, to protect the rest of the population.

Herd immunity from natural infection

Allowing the infection to spread among 60% of the population in order to protect the remaining 40%, requires very close monitoring, in order to flatten the epidemic curve, whilst not overwhelming healthcare capacity and not suppressing infection completely.  Herd immunity does after all require a controlled rate of continuing infection.

If you want to play this scenario safely, you would want to spread the disease among healthy young people, who normally have mild symptoms, but keep the vulnerable and the elderly in care homes in a secure bubble.  But we must bear in mind that old people in the UK make up nearly 20% of the population, and that 25% of young adults have at least one chronic condition, also putting them in the high-risk group.

We know that, unlike with flu, Covid can result in serious long-term symptoms (long Covid), even among young adults who would usually have a mild infection.

Even more serious is the fact that studies have shown that not every patient recovering from Covid-19 develops protective antibodies.  Many may not have antibodies at all, and some may have the wrong ones!  Only 15% of patients have the correct protective antibodies, post-Covid.  We don’t know how long this natural immunity lasts.  And the matter is compounded by the appearance of new Covid-19 strains.

Moral and ethical considerations

Allowing the virus to spread is not ethical.  This simply results in a life-threatening condition among large groups of the vulnerable older population.

Many politicians have realised that the economy cannot be restored before the epidemic is dealt with effectively.  This is because the high mortality rate has put pressure on the government to enforce strict public health measures (lockdown) with a negative impact on the economy.

We needed widespread testing outside hospital, not only to find cases and contact isolation, but also to ensure the herd immunity target is reached.  But this did not happen.  Again, the accuracy of the test is lower than previously thought.  The WHO reported a high false positive rate in current tests.  This means that our public health decisions are being made based on inaccurate information.

Unlike those countries who imposed stricter measures earlier, the UK has recently passed the grim milestone of 100,000 deaths.

We had three lockdowns, while airports were kept open for international and domestic flights.  A total of 25,000 deaths took place from mid-March to mid-April.  This was the time when large numbers of elderly patients waiting for social care, were moved from hospitals into the care homes to free the acute hospital beds.  This apparently happened without adequate preventive measures taking place.  The most recent 25,000 deaths are most probably related to the relaxation of the public health restrictions over the festive season.

Your body’s response

When you are challenged by a Covid-19 infection, your immune system responds in two stages.  The first line innate immune response takes immediate but non-specific action to engulf invading viruses and pass the information to the adaptive immune system to organise specific and more powerful action.

The adaptive immune system gets the message to activate lymphocytes within 3-5 days, after which the adaptive immune system takes over to fight the battle on its own.

Studies confirm Covid-19 reinfection is rare in the 90 days after the initial natural infection, but we do not know how long this natural immunity lasts.  Having a natural infection or vaccination will leave the body with specific immune memory cells.  These will recognise the Covid-19 virus and will launch effective attacks to clear the virus if infection happens in the future.

Could we achieve herd immunity with effective vaccination?

Israel and United Arab Emirates lead the world in vaccination, both covering 25% of their population.  So far, the UK has covered 8 million healthcare workers and the elderly population, including those living in care homes.

A study of 200,000 people over 60 who have been vaccinated and 200.000 people not vaccinated showed 33% fewer positive tests in the vaccinated group.

Vaccination helps your immune system create antibodies to protect you against infection, without having to suffer the disease.  It also prevents severe illness, particularly in the vulnerable population.

Facts about the Covid-19 vaccination

  • Adverse allergic reactions are very rare, though vaccination can cause mild, short-lived side effects such as tiredness, headache, muscle and joints pain, fever, chills, injection site swelling, redness or pain. These are indications that your body has made a response to build up a protective immunity against Covid-19.
  • Duration of protection is currently unknown.

Covid-19 requires two shots several weeks (3 to 12) apart to offer full benefits.  The first dose helps the immune system to create an immune response.  The second boosts the immune response to ensure more sustained protection.  You gain 50% immunity on day 10 but 95% immunity after the second dose.  (More than one shot is not uncommon in the world of vaccination.)

It takes a few weeks for the body to produce adequate immunity after vaccination.  A person unlucky enough to catch the virus before or just after vaccination may get sick, as the vaccine hasn’t got enough time to provide protective immunity.

Covid-19 new strains

New strains identified in the United Kingdom, South Africa and Brazil appear to be more transmissible but not hugely more deadly compared with the original virus.  Early reports show that the new strains are associated with a 70% faster transmission rate, but, whilst 10 out of 1,000 are expected to die from the original virus, only slightly more – 13 to 14 in 1,000 – will die from the new strains.

Early reports speculated that vaccination may be less effective against the more contagious new strains.  However, more recent studies reassured us that the current UK vaccines are effective.  Even if the vaccine is less effective in preventing infection, it does reduce the risk of having a severe infection and the risk of dying from Covid-19.

We need to use all public health tools available at our disposal to stop the pandemic.  These include wide testing and contact surveillance, and social distancing, hand washing and wearing face masks.  Measures such as these, plus vaccination, offer the best possible protection against Covid-19.

Please take these measures, my friends.  At the end of the day, you have nothing to lose from being vaccinated and a great opportunity to gain immunity without suffering the disease.  The only concern would be if you have a history of serious allergic reactions including anaphylaxis. This will require taking precautions, please check with your GP.

As always, I would welcome any questions or comments on this issue – and I will do my best to answer you.  Stay safe.  Thank you! 


Natural herd immunity should not be used as a means of pandemic control

U.K. is still aiming for deliberate ‘herd immunity’

Coronavirus disease (COVID-19): Herd immunity, lockdowns and COVID-19

Complications of Viral Mutation Rates, Journal of Virology, DOI: 10.1128/JVI.01031-17,to%20correct%20mistakes%20during%20replication.

Adaptive Value of High Mutation Rates of RNA Viruses: Separating Causes from Consequences, Journal of virology, DOI: 10.1128/JVI.79.18.11555-11558.2005

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