Herd Immunity:  What Does it Mean?

March 4, 2021

Herd Immunity:  What Does it Mean?

Herd Immunity is the threshold point at which the proportion of susceptible individuals falls below the threshold needed for transmission.  It is a balancing act, like a teeter-tooter.   It is like a moving target as one puts different weights on either end.  Therefore, it is difficult to accurately predict when the threshold will occur. The bottom line is no one really knows.  We can only speculate.  Using data from John Hopkins Coronavirus Resource Center and Worldometers Coronavirus site, I pieced together a good estimate of when this might occur.  Again, go to the sites, do your own research.  See what the numbers are saying.

Herd immunity starts when the transmission of the virus is decreased to the point susceptible individuals are no longer coming into contact with high loads of the virus, and therefore, do not get the disease.  This is an indirect protection.   As the virus has fewer hosts to infect it will start to die out.

What Percent of the Population Needs to be Immune to Acquire Herd Immunity?

A paper in Immunity, May 2020, states to reach Herd Immunity, greater than 67% of the population has to have acquired immunity.***   This data was based on early  Covid-19 data from the Chinese and Italians.  They figured the reproduction number (RO) was 3, meaning 2 out of 3 susceptible people would have to be immune before each carrier would infect fewer than one person. This is the point at which the virus dies out.  A paper in the International Journal of Public Health, Nov 2020, looked at an Italian community in Bergamo that reached 40% acquired immunity and still got hit by a second wave of virus, although with lower incidence. Their conclusion was they didn’t know what % herd immunity would be effective for Covid-19, although they postulated over 60% would be needed.**   Sweden reached a kind of ‘herd immunity for deaths’ in that their second wave of deaths from the virus extinguished a month and ½ faster than their first wave with only 7% of their population having acquired immunity. At the same time, their number of positive cases plateaued at approximately 4300 cases a day which was higher than the first wave.  Conclusions? Are they better at treating the disease? Or is the new strain less virulent? Or did people acquire some immunity during the first wave that was not detected via early testing?

Acquired immunity in the US as of Feb 28th equals the sum of the below bullets:

  • The number of people who have had Covid-19, 6 million
  • The number of people fully vaccinated is 23.7 million @ at 94% efficacy rate, 3 million
  • The number of people with 1 vaccine only is 49.3 million @ at current 70% efficacy rate, 51 million

Therefore, 82.4 million people have reached acquired immunity in the US.

Goal for Herd Immunity:  67% of the population or 222.6 million people. 

  • Therefore, 137.4 million more people have to acquire immunity to achieve herd immunity
  • Currently, approximately 70,000 people a day are diagnosed with Covid -19
  • Approximately 1 million (and rising)/day are getting their first vaccine @70% immunity= 700,000 a day
  • Approximately 1 million (and rising)/day are getting their second vaccine @ 94% immunity is 940,000 a day,

Therefore,  1.71 million people are reaching  immunity every day

When Do We Reach Herd Immunity?

Using the above numbers, it will take another 94 days or 13.5 weeks to reach herd immunity according to current numbers, which is the first week in June.

Biases not listed in the numbers are:

  • The exponential increase in numbers of vaccines being distributed and given per day
  • Asymptomatic cases not recorded.
  • People who have had Covid-19 who also get the vaccine are not recorded.
  • People who have already died who have not been deducted from the number of people positive for Covid
  • Current antibody testing misses T cell immunity people have innately to the disease. These are people who get exposed but never get the disease. My youngest daughter is an example of this seeing 60 patients a day, while all co-workers got sick, she never got the disease!  Subsequently, she did get the Pfizer vaccine and now does have IgG antibodies.

Recurring Question:

Again, I pose the question.  If we treat everyone right now with one dose of Ivermectin every 2 weeks with 100% no transmission of disease, how long would it take to ‘eradicate’ the disease just by giving Ivermectin alone.

Then ask the same question factoring in the exponentially increasing numbers of vaccines being given? 

No one knows the answers to these questions as they have not been posed yet by NIH, FDA or CDC.   Why not?

Vaccinations plus giving a cheap medication having virtually no side effects could bring this pandemic to a close in record time.  How many people have died because of lack of initiative to treat early?

Think how much faster we can say:  Good-bye masks, good-bye social distancing, good-bye mental health pandemic induced diseases.   Hello to hugging your loved ones, going to school and public places, interacting with other humans, and traveling freely without ridicule.  Being free to live as we like again is a sweet aspiration.

Next week… How does the mRNA vaccine work?  Is it a vaccine?  Does it work ‘genetically’?

Have a super awesome day.    Dr D

Posted in Covid19