Study by Lancet casts Doubt On Feasibility Of Herd Immunity To Tackle COVID-19

herd immunity
herd immunity

Explained: Doubts About The Herd Immunity

A recently issued study from The Lancet stated herd immunity is very hard to achieve, considering the current stage of COVID-19 pandemic. Whereas, a different set of scientists said that herd immunity is impossible in Spain. While most of the data in this research was based on the seroprevalence ( percentage of the amount of pathogens in the whole population ) of the national population, the conclusion seems a little bit confused.

What do you mean by Herd Immunity?

The term herd immunity points to the situation, where a majority of people in the country will become strongly immune to the virus and hence decrease the spread of the disease drastically. Even though this concept is specifically used for vaccines, the stated situation is possible if a certain majority (80%+) are infected from the virus.

This works like this. When a majority of people are infected from the virus at least once in their lifetime, they become immune to the virus because their body becomes successful in creating antibodies that can fight the virus. Also, an already immune person cannot spread the virus even if he gets infected again. Therefore, this whole process breaks the entire chain of spreading, and hence infection spreading drops drastically.

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Credit: NIAID

What are the new findings?

The already conducted large-scale seroepidemiology research stated that with only 5% of the entire Spanish population being immune, the rest 95% of the population is still vulnerable to the SARS-CoV-2.

After testing over 66 thousand participants over 7 provinces from April 27 — May 11, the study said that the seroprevalence of the country was just 4.6% by immunoassay and only 5% by point of the care test. Only Madrid and Barcelona are the places where the seroprevalence is greater than the whole nation,i.e. 10% and 5% respectively. With over 1.1% of infants, 3.1% of children in the range of 5 years -9 years, and 6% of 45+ years, the national seroprevalence average is slowly increasing day by day.

What is the significance of the study?

The research is the largest serological study across the whole of Europe till now when it comes to capturing the real COVI-19 infected numbers. The research gave an estimate that the seroprevalence number of the entire country ranged from 3.7% to 6.2% and that around 376k — 1042k people went undetected in the population.

The implications of this study?

While the normal seroprevalence studies provided data only the previous exposure to a virus, the current study helped to strengthen the argument that reaching herd immunity is not possible considering the current situation. German Virologist Mr. Benjamin Meyr and Mrs.Isabella Eckerle said that ‘ achieving herd immunity by natural infection is highly dangerous and unethical and, in fact, very hard to achieve. If this happens we will fail as a society”, building on the previous point, they also said that it can also trigger a second wave of SARS-Cov 2 pandemic. Therefore concluding, even with countries with high seroprevalence percentage, the pandemic is very far from getting over.

Why is herd immunity impossible?

The whole study was based on the UK COVID-19 fighting strategy. Initially, when UK planned to allow 60% of their population to get infected so that a certain level of the herd immunity can be achieved, only 5% of the total population were successful in producing the antibodies required to fight the disease, which was the primary aim behind the whole strategy.

The period of immunity is known well, as scientists think that the immunity is only for a mere few months to a couple of years, after which everyone will be vulnerable to the virus again.

What did other seroprevalence studies reveal?

On June 11, the previous study revealed that for every single convid-19 infection, there will be 11.6 new infections from i. With the basis of the geneva study on around 2700 patients, the spread showed only 4.8%, 8.5%, 10.8%, and 6.6% in the first to the fourth week respectively.

Another study on June 5 in China on the antibodies immunoglobulin G and M stated that out of the 17368 infected people, thee seropositivity remained only 3.2 to 3.8 percentage when considering different cohorts. It was also discovered that health workers had a much higher seroprevalence of 3.3 % and this number decreased as we move out from the epic center of the disease.

Another Research paper from the famous Journal of Medical Association on May 18 said that the seroprevalence number of Los Angeles county was around 4.65%. Considering the number of fatalities and infected much more than the registered ones, these numbers may be just the tip of the iceberg.

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