COVID-19 Natural Immunity Debate Continues

Although evidence suggests antibody responses following COVID-19 vaccination provide better neutralization of some circulating coronavirus variants than does natural infection, few real-world epidemiologic studies exist to support the benefit of vaccination for previously infected persons, wrote the U.S. CDC’s Morbidity and Mortality Weekly Report issued on August 6, 2021.

The natural immunity Vs. COVID-19 vaccine-generated immunity debate continues after about eight months because it isn’t always clear how long any virus immunity persists. 

Since COVID-19 is a new disease, scientists are still working out precisely how the body fends off the SARS-CoV-2 beta coronavirus.

According to the CDC, immunization is also determined by other factors besides antibodies, such as T and B cell memory, which some studies estimate could last for years.

However, in a new case-control study among Kentucky residents infected with the initial SARS-CoV-2 variant in 2020, being unvaccinated was associated with 2.34 times the odds of reinfection with the newer variants compared with being fully vaccinated.

Overall, 246 case-patients met eligibility requirements and were successfully matched by age, sex, and initial infection date with 492 controls. Among the population included in the analysis, about 60% were female, and 83% of case-patients were initially infected during October–December 2020.

Among case-patients, 20.3% were fully vaccinated, compared with 34.3% of controls. 

Kentucky residents with previous coronavirus infections who were unvaccinated had 2.34 times the odds of reinfection (OR = 2.34; 95% CI = 1.58–3.47) compared with those who were fully vaccinated; partial vaccination was not significantly associated with the newer virus reinfection (OR = 1.56; 95% CI = 0.81–3.01).

This finding supports the CDC’s recommendation that all eligible persons be offered COVID-19 vaccination, regardless of previous SARS-CoV-2 infection status.

However, the findings in this report are subject to at least five limitations, says the CDC. 

‘This is a retrospective study design using data from a single state during two months; therefore, these findings cannot be used to infer causation. Additional prospective studies with larger populations are warranted to support these findings,’ said the CDC.

Previous research focused on SARS-CoV-2 virus natural immunity Vs. COVID-19 vaccine generated immunity debate includes, but are not limited to the following:

A letter published in The Lancet in February 2021 discussed an experiment in which London-based healthcare workers were given a single dose of the Pfizer vaccine. Half of the healthcare workers had previously recovered from COVID-19, and they experienced the greatest boost in antibodies.

Science published a research article in February 2021, where the researchers found durable immune responses in most people studied. Antibodies against the spike protein of SARS-CoV-2, which the virus uses to get inside cells, were found in 98% of participants one month after symptom onset. As seen in previous studies, the number of antibodies ranged widely between individuals.

The journal Nature published an article that found ‘people who recover from mild COVID-19 have bone-marrow cells that can churn out antibodies for decades, although viral variants could dampen some of the protection they offer.’

Recovered COVID-19 patients retain broad and effective longer-term immunity to the disease, suggests an Emory University study published in the journal Cell in July 2021. These findings have implications for expanding understanding about human immune memory as well as future vaccine development for coronaviruses.

Emory Vaccine Center director Rafi Ahmed, Ph.D., stated in a press release issued on July 22, 2021, “The (new) study serves as a framework to define and predict long-lived immunity to SARS-CoV-2 after natural infection.”

“We also saw indications in this phase that natural immunity could continue to persist.”

The Emory researchers found that the immune response increased with disease severity and with each decade of age regardless of disease severity, suggesting that additional unknown factors influence age-related differences in COVID-19 responses. 

In following the patients for months, the Emory researchers got a more nuanced view of how the immune system responds to COVID-19 infection. The picture that emerges indicates that the body’s defense shield not only produces an array of neutralizing antibodies but activates specific T and B cells to establish immune memory, offering more sustained defenses against reinfection.

“We saw that antibody responses, especially IgG antibodies, were not only durable in the vast majority of patients but decayed at a slower rate than previously estimated, which suggests that patients are generating longer-lived plasma cells that can neutralize the SARS-CoV-2 spike protein,” added Ahmed.

“Vaccines that target other parts of the virus rather than just the spike protein may be more helpful in containing infection as SARS-CoV-2 variants overtake the prevailing strains.”

“This could pave the way for us to design vaccines that address multiple coronaviruses,” concluded Ahmed.

PrecisionVaccinations publishes fact-check research-based vaccine news.

Note: The CDC MMWR stated: Although laboratory evidence continues to suggest that vaccination provides improved neutralization of SARS-CoV-2 variants, limited evidence in real-world settings to date corroborates the findings that vaccination can provide improved protection for previously infected persons.