Source: Thomas T. Siler, M.D.

After a year now of dealing with the SARS-COV-2 virus, we have learned a great deal about the pandemic. The elusive goal has been to acquire herd immunity and have life go back to normal. However, our mainstream media and some governmental health authorities have ignored parts of the scientific picture that could help us understand herd immunity. They have placed excessive importance on vaccination as the only way to herd immunity. This is not entirely true. There is scientific data showing that we may be closer to herd immunity and the end of the pandemic than the media and government let on.

At the start of the pandemic, we were told that the SARS-COV-2 was a “novel” virus, meaning a brand-new virus that has not been seen before. If this were true, then it would be much harder to treat or make a workable vaccine.

Fortunately, this was not true. SARS-COV-2 is in the family of coronaviruses and shares common characteristics with other members of the same family. Four coronaviruses commonly circulate in our population and cause symptoms of the common cold. Did persons have some cross-immunity to the “new” SARS-COV-2 virus from previous infections with other viruses in the Coronavirus family? The answer was yes.

T cells (a type of white blood cell) and antibodies can both be measured to study immunity. Studies of T cell function in 2020 showed that patients who had not been exposed to SARS-COV-2 in several countries had evidence of cross-reactivity from known coronaviruses and SARS-COV-2. The range of cross-reactivity ranged from 18% in Sweden to 51% in Singapore.

Interestingly, the countries with a higher level of T cell cross-reactivity to SARS-COV-2 had a lower death rate during the pandemic. A study of blood bank samples from 2015 to 2018 in the U.S. showed 50% of the samples had cross-reactive T cells to SARS-COV-2 from prior coronavirus infections.

The dramatic initial models guess how the pandemic might progress assumed there would not be any pre-existing immunity. It now appears this is incorrect. Some levels of pre-existing immunity may explain why some people don’t get infected and why others have a milder case of COVID-19. Because children have a higher chance of catching the “cold” viruses, this may also partly explain why children are not affected very much by SARS-COV-2.

This also happened in the 2009 H1N1 Swine flu pandemic. It was found that 30% of people over 60 years old had prior immunity to Swine flu from earlier immunity to other influenza infections. This fact lessened the severity of that pandemic, but that fact seems to have been forgotten in the current pandemic.

In addition to pre-existing immunity, persons who have had COVID-19 are generally thought to be immune. Factoring in a correct case count can show we are closer to herd immunity than we thought. Many actual cases of COVID-19 infection have not been counted because patients may have mild infections, may not get tested, or may not have access to testing. In August, the World Health Organization estimated that 10% of the world’s population had contracted COVID-19 infection (760 million). At that time the reported case count was 35 million (20 times lower).

In the United States, the CDC estimated in late November that the total cases could approach 100 million. The actual case count in the United States at the end of December was 20 million (as much a 5 times lower).

So, if most populations have 20-50% pre-existing immunity from prior Coronavirus infections and the actual numbers of COVID-19 infections are much higher (3.5 to 20 times higher), then we could be approaching herd immunity (which is guessimated at 70%) now, even with our current low level of vaccination. If you make those calculations for the United States, then 45 to 90% of the American population could be immune now.

Dr. Mike Yeadon, a former Pfizer scientist with 30 years of experience in immunology, says the pandemic effectively ended, even before we began to vaccinate people. Dr. Marty Makary wrote in a recent article in the WSJ that he feels herd immunity could come by April and also be in effect before we have vaccinated “everyone.” Both these scientists came to this conclusion by saying that more people have already been infected (up to 150 million for the U.S.) already and there was pre-existing immunity at some level for a portion of the population.

This seems to be what is happening in our experience of COVID-19 tracking. Since January 8th there has been a significant drop in cases in the U.S. Hospitalizations and deaths are also going down in almost every locale.

This cannot be explained by changes in behavior (masking, etc.) and it is too early for the low level of vaccinations to explain this fall in infections. This drop happened despite more travel over Christmas and the holidays.

This is good news and it is hard to understand those in the government health agencies and politicians who say we must vaccinate 100% of people in order to get out of the pandemic. This is clearly not true.

We must still protect the elderly and those with pre-existing conditions that could make patients susceptible to more severe infections. These persons should consider taking the vaccines. In my opinion, persons with a low risk of serious infection (healthy persons under 70) can wait on vaccination. The vaccines were produced very quickly, but they have not been through the usual trials and time to determine if there are any long-term side effects. They should be considered experimental at this point.

Variants of the virus are not likely to change this analysis. Viruses mutate all the time and usually are not more deadly or a new, untreatable form. Sensational headlines in the media about contagiousness are always followed by disclaimers that studies on the variants are preliminary and more study will be needed.

This view should also affect the rationale for lockdowns and closing businesses, allowing states to open up sooner. Florida, South Dakota, and Georgia have lessened restrictions on the public and businesses months ago and are doing well. Texas, Mississippi, Arizona, and Connecticut have just lessened their COVID-19 mandates and opened-up more completely.

If it continues to appear that herd immunity is being reached and cases, hospitalizations, and deaths continue to go down, we should lobby all our states to lessen restrictions by the end of spring. The pandemic can be managed with a more targeted approach and the healthy can go on with their lives with less restriction. The pandemic, indeed, may finally be coming to a close.