COVID-19 Continues to be a Puzzle for Epidemiologists

July 13, 2020 – There’s nothing like a new pathogen when it first infects a human population. Having no previous experience with it, the medical response attempts first to treat symptoms and then second to begin searching for a preventive or cure.

In the case of COVID-19, two recent papers shed new light on the virus and its propensity to defy preconceived ideas. The first paper still in pre-print which means it hasn’t been peer-reviewed, describes antibody response. The second describes a study of Italian post-COVID patients looking at symptom persistence for those who no longer have the virus.

Evaluating the Body’s Response to COVID-19

In a collaborative paper written by clinical medical researchers at King’s College London, the Centre for Clinical Infection and Diagnostics Research, Guy’s and St Thomas’ NHS Foundation, and the University of Kent in the United Kingdom, the authors studied antibody responses in infected patients.

They noted that antibodies first appeared in the most infected individuals within 10 to 15 days after symptoms emerged. Serum tests after 94 days revealed that the level of antibody response was affected by the severity of the infection, but that levels declined significantly over the following 60 days suggesting that immunity to COVID-19 may be only transient and not permanent.

In the paper’s conclusions, the authors raise the issue that the number of antibodies present in previously infected people over time, may be insufficient to stop reinfection from occurring.

For those developing vaccines to create a “robust” antibody response, these findings are problematic. For a vaccine to be effective, it may mean frequent repeat inoculations of the population as the only way to ensure long-term protection.

Is this any different from the annual influenza vaccine? Yes and no. With influenza, we have a virus that rapidly evolves from year to year. The vaccines that are administered to the general population are usually a cocktail reflecting the seasonal changes to the virus. What happens in terms of influenza strains in Australia six months before determines the vaccine cocktail administered in the northern hemisphere.

With COVID-19, we as of yet don’t know at what rate the virus will evolve. There is a suggestion that the virus currently devastating the United States, India, Brazil, and South Africa, is already a new strain, more potent in its spread than what first emerged from Hubei Province in China late in 2019. Should COVID-19 exhibit the same evolutionary characteristics of influenza virus strains, then annual inoculations will become the primary means of fighting it.

Symptom Persistence in Acute Cases

A research letter published on the JAMA Network authored by doctors from the Fondazione Policlinico Universitario Agostino Gemelli, in Rome, Italy, has described persistent symptoms in patients who seemingly have recovered from COVID-19.

Involving 143 patients from April 21 to May 29, 2020, with a mean age of 56.5 (ranging from 19 to 84-year-olds), 53% women, and an average hospital stay of 13.5 days, the study included subjects that had both non-invasive (15%) and invasive ventilation treatment (5%).

What emerged was a consistent pattern of persistent long-term symptoms in nearly 90% of the patients. The one most commonly described was fatigue and dyspnea (shortness of breath) 60 days after the onset of the infection. Other symptoms included joint and chest pain with 10% still experiencing a cough and another 10% indicating that their sense of smell had not returned. Over half exhibited three symptoms typical of the virus. A mere 13% were symptom-free.

Although statistically a small sample, what can we surmise from this study? Survivors of COVID-19 don’t come out of the infection without baggage.

A Final Word

On a personal note, in my own post-COVID-19 recovery and that of my wife, we contracted the virus early in April, and now in mid-July we continue to have persistent symptoms without any evidence of the virus in our bodies.

How do I know I no longer have COVID-19? Yesterday, I had my fourth COVID-19 test and it came back negative. That’s four tests since April 24th. By now I think it is pretty clear that I am no longer infected.

The symptoms that were COVID-specific have largely moderated. But what has persisted is arrhythmias caused by the virus infecting my heart, pain in my joints, transient skin rashes, and chronic fatigue. All four are within the spectrum of COVID-19 symptoms. The Italian researchers could have added me to their study and I would have fit in.