Where Do Our Chances Lie in the Fight Against COVID-19?

Vaccination or Natural Immunity

Vaccination or Natural Immunity

The science community has been looking into herd immunity as a way to curb the spread of COVID-19. Dr. Bharat Pankhania, a Senior Clinical Lecturer at the University of Exeter Medical School, said:

The concept of herd immunity is to try to create an extremely large group of people who have immunity against an infectious agent. This means either vaccinating, or allowing people to get infected and recover, so they develop memory against the infecting agent and produce antibodies when encountering the infectious agent again.

When most people are immune they act as barriers. The virus can’t infect their body so they no longer serve as a vector to send it forward to the next person. This offers some protection to new-borns, the elderly, and those with pre-existing illnesses.

It’s the best way to prevent contagious diseases from circulating throughout a population because it slows down the spread of the virus and eventually eliminates it.

Scientists have predicted that this can be achieved if more than 60% of a population has immunity against COVID-19.

Herd immunity through vaccination

The safest and quickest way to get herd immunity is through vaccination. It involves administering a tiny amount of the microorganism into the body which will induce an immune response forming antibodies that provide protection. The best part is that vaccination doesn’t cause illness.

Using this approach we have contained measles, mumps, and rubella. We have successfully eradicated smallpox. And almost eradicated the poliovirus.

The BCG vaccine that protects from upper respiratory infections has now shown to also protects against a variety of pathogens. Scientists reported that the BCG vaccine could protect health-care workers and other vulnerable individuals from severe symptoms of COVID-19.

Today many reap the benefits of a robust immune system without ever experiencing the uncomfortable symptoms of illness.

However, vaccination could be tricky against COVID-19.

That’s because coronaviruses are made of RNA instead of DNA. Vaccinations targeting DNA viruses (like those mentioned above) have a high success rate, while those targeting RNA viruses have a success rate of about 45% e.g. the flu virus.

RNA has a mutation rate that’s 1000 times higher than DNA. This means like flu, the coronavirus could mutate into different strains and continue to circulate seasonally.

Prof Willem van Schaik, Professor of Microbiology and Infection, University of Birmingham, said:

The problem with flu is that it is difficult to know which strains will be causing infections at any given point in time and so that is why the flu vaccine is not always 100% effective.

To contain the coronavirus scientist would have to invent a new vaccine each year (like we do with the flu virus) to keep up with the mutation rate. As we’ve all witnessed with the current situation making a vaccine takes many months.

To alleviate these problems, Moderna manufactured a novel vaccine consisting of just messenger RNA packed in a nanoparticle, called mRNA-1273. It is relatively cheap to manufacture which caters to the high mutation rate of RNA. It may cause fewer side effects because the body is manufacturing viral proteins and it’s not directly from the virus. It can also be developed and distributed very rapidly.

This approach on vaccination is ingenious because once the vaccine is in the body the mRNA-1273 will enter the human cells and signal them to produce a harmless version of the viral spike protein. Once produced, the immune system will recognize the spikes as foreign and antibodies will be unleashed. These antibodies will then prevent future infection.

So far Moderna’s vaccine has gone through the first phase of clinical trials and will start the second phase in the second quarter of 2020. This study will evaluate the safety, reactogenicity, and immunogenicity of mRNA-1273. Based on the first phase it seems promising because Moderna has teamed up with Lonza to manufacture up to 1 billion doses of mRNA-1273 to be used worldwide.

Herd immunity through infection (natural immunity)

Herd immunity through infection is the oldest way of containing viruses some regions still use this approach. For example, many people can’t afford the yearly flu vaccine they rely primarily on their immune system.

When the infection rate of the influenza virus is high we call it flu season. Many get infected, develop antibodies against the virus then recover. They then act as a barrier to the spread of the virus. When enough people act as barriers, the influenza virus disappears till a new strain appears the next flu season.

So if you didn’t get flu last season it could be that you were asymptomatic or you were protected by herd immunity.

Our immune system is highly specialized to detect, create antibodies, and eliminate intruders. Which is why we have survived for decades despite deadly microorganisms, infectious viruses, and varying pathogens.

When a person is exposed to a virus, it grabs and penetrates the outer walls of human cells. Once inside, it hijacks the cell’s system and makes copies of the virus. As soon as the immune system recognizes the intruder it is flagged and attacked by antibodies.

If the immune system delays the virus keeps multiplying and infecting more cells.

The immune system can be so robust that the virus is eradicated before symptoms develop, these people are asymptomatic. Those with ‘mild symptoms’ implies that their immune system is fighting the infection and those with ‘serve symptoms’ implies that the virus is taking over most of the cells.

It is estimated that 2% of the world’s population are asymptomatic carriers of the coronavirus.

Of the active COVID-19 active cases worldwide 98% show “mild symptoms” and don’t require specific medical treatment while 2% of active cases are critical and require intervention.

The current lockdown and social distancing are put in place so that people who suffer the more severe form of the disease are cared for properly; if not the healthcare system would be overwhelmed. Professor Peter Openshaw, Past President of the British Society for Immunology and Professor of Experimental Medicine at Imperial College London, said:

Modeling studies show that, over time, we can expect 60–80% of the population to be infected with COVID-19. Generating herd immunity in the population, and particularly in younger individuals who are less likely to experience serious disease, is one way to stop the disease spreading and provide indirect protection to older, more vulnerable groups.

Theoretically, if enough people could be mildly infected, they would be protected from the virus and not pass it on to others. The trick is to infect only people who will have mild infections but, that will be a challenge as no one knows how to do to that.

Currently, The Swedish government has implemented this strategy, so life for the Swedish people remains practically unchanged. Primary schools are open, as are bars and restaurants though gatherings in crowds over 50 is prohibited and many are still advised to work from home if they can. In the meantime, as of Monday, the number of cases in Sweden totaled 30,143 they are well on their way to herd immunity before the winter season when the virus is expected to spike.

Both vaccination and natural immunity show a high probability of curbing COVID-19 through herd immunity.

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