There’s good news on the COVID front, but you wouldn’t know it to read headlines featuring the CDC or other government health agencies. With such large numbers and ever-changing definitions, it is hard for many Americans to clearly grasp what portion of the population has either recovered, been confirmed, or died from COVID. And many times no acknowledgment is given to those who have natural antibodies but have never had a confirmed case or were unaware that they even had the virus.
Studies have come out recently that are encouraging in the number of Americans who developed natural immunity within varying times of the pandemic due to these unknown cases.
The CDC explains why case numbers may actually be higher than those reported:
- Not all patients with symptoms seek care or testing services. Not all sick patients seek care or are tested for COVID-19, and therefore they are not included in national case reports. To approximate the number of symptomatic people who never sought medical care, researchers use data from COVID Near You (CNY) and Flu Near You (FNY) sites on health care seeking behaviors. While COVID Near You launched in March 2020, FNY has been collecting self-reported influenza participatory data since 2011.
- Patients do not have symptoms. Some people infected with SARS-CoV-2 never show symptoms (they have asymptomatic infection). People with asymptomatic infection are very likely to go undetected. The percentage of asymptomatic infections is reported in the literature and varies by age group. In people 0-64 years old, a range of 5%-24% is used to estimate asymptomatic infections, and for people 65 years and older, a range of 5%-32% is used.1
The First Six Months; COVID Case Numbers Through July 2020
A study was published in the Science Translational Medicine periodicial. The study reveals the widespread SARS-CoV-2 virus was far greater in the first six months of the pandemic than previously thought.2 This study was designed to give us a snapshot up to July 2020 and indicated a nearly five-fold increase in cases from 3.5 million to 16.8 million.
Our results estimate that as of July 2020, there were about 4.79 undiagnosed infections (95% CI, 2.76 to 6.82; fig. S6) for every identified case of COVID-19, suggesting a potential 16.8 million undiagnosed infections by July 2020 in addition to the reported 3.5 million diagnosed cases in the United States. These data suggest that a higher level of infection-induced immunity exists in the U.S. population than previously predicted.2
The study was designed with over 11, 363 participants aged 18 and over. Participants first answered survey questions on a phone call then followed up with a blood sample to test for antibodies submitted to the NIH lab. Participants were excluded if they had past confirmation of COVID, past exposure to COVID, or had symptoms congruent with a COVID diagnosis.3
Care was taken to ensure the participants were representative of the overall U.S. population according to recent census data:
All volunteers were emailed an initial survey to collect basic demographic characteristics. Survey responses were de-identified and aggregated by subcategory of state, type of locality approximated from zip codes, age, sex, race, and ethnicity. Target sample sizes for these subcategories were determined from the U.S. census and were updated every evening based on the characteristics of people who had already enrolled to assure that individuals in each subcategory were enrolled evenly over time.2
Six Months Later; Numbers For All of 2020
New York’s Columbia University’s Department of Environmental Health Sciences, Mailman School of Public Health, conducted a study to analyze the likely spread of COVID through the end of 2020. Their analysis showed that “one in three Americans already had COVID-19 by the end of 2020.”4 The study also revealed that 1 in 130 American’s were contagious at the end of December 2020 with a similar rate of those infected but not yet contagious.4 The number of cases would continue to climb with that many contagious people in the community, many of whom may not have been aware they were contagious or had the virus.
The Numbers of Natural Immunity Versus Vaccine Induced Immunity
A recent study showed the long-lasting, durable, and robust immunity infection offered a person versus the protection of the vaccine.
Those who hadn’t had a natural infection but had been vaccinated showed a 13-fold increase for a breakthrough compared to those who had been infected and recovered. Rates of symptomatic disease as well as COVID-19 related hospitalizations was also significantly greater than those who had been previously infected.5
The paper concludes:
This study demonstrated that natural immunity confers longer lasting and stronger protection against infection, symptomatic disease and hospitalization caused by the Delta variant of SARS-CoV-2, compared to the BNT162b2 two-dose vaccine-induced immunity.5
CDC’s Death Count
The CDC uses a model in which COVID-19 is specifically listed as a contributing factor or cause of death to consider the death count number:
Coronavirus disease deaths are identified using the ICD–10 code U07.1. Deaths are coded to U07.1 when coronavirus disease 2019 or COVID-19 are reported as a cause that contributed to death on the death certificate. These can include laboratory confirmed cases, as well as cases without laboratory confirmation. If the certifier suspects COVID-19 or determines it was likely (e.g., the circumstances were compelling within a reasonable degree of certainty), they can report COVID-19 as “probable” or “presumed” on the death certificate. COVID-19 is listed as the underlying cause on the death certificate in 92% of deaths.6
The CDC also utilizes a statistical model to consider cases that hadn’t been attributed with any connection to COVID-19 to reach its total COVID-19 related numbers:
CDC uses a statistical model to estimate the number of expected deaths from all causes assuming that there was no circulation of COVID-19 (that is, those deaths expected in the absence of any COVID-19 illnesses). Researchers then use the model to predict the number of all-cause deaths that would have occurred taking into account information on COVID-19 circulation. To obtain the number of unrecognized COVID-19 deaths, the number of expected all-cause deaths (without COVID-19 circulation) are subtracted from the number of predicted all-cause deaths (with COVID-19 circulation). The model is used to calculate estimates by state and age (for six age groups: 0-17, 18-49, 50-64, 65-74, 75-84, and ≥85 years).
Once investigators estimate unrecognized COVID-19 deaths, they add documented COVID-19 deaths to the unrecognized deaths to obtain an estimate of the total number of COVID-19-attributable deaths.7